     [file common.texi not included]

This document is an unofficial reference manual for LaTeX, a document preparation system, version of March 2018.

This manual was originally translated from LATEX.HLP v1.0a in the VMS Help Library.  The pre-translation version was written by George D. Greenwade of Sam Houston State University.  The LaTeX 2.09 version was written by Stephen Gilmore.  The LaTeX2e version was adapted from this by Torsten Martinsen.  Karl Berry made further updates and additions, and gratefully acknowledges using Hypertext Help with LaTeX, by Sheldon Green, and LaTeX Command Summary (for LaTeX 2.09) by L. Botway and C. Biemesderfer (published by the TeX Users Group as TeXniques number 10), as reference material (no text was directly copied).

Copyright 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018 Karl Berry.

Copyright 1988, 1994, 2007 Stephen Gilmore.

Copyright 1994, 1995, 1996 Torsten Martinsen.

Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies.

Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions.

LaTeX2e: An unofficial reference manual
***************************************

This document is an unofficial reference manual (version of March 2018) for LaTeX2e, a document preparation system.

About this document
*******************

This is an unofficial reference manual for the LaTeX2e document preparation system, which is a macro package for the TeX typesetting program (see Overview).  This document's home page is LTXREFMAN_HOME_PAGE.  That page has links to the current output in various formats, sources, mailing list archives and subscriptions, and other infrastructure.

In this document, we will mostly just use `LaTeX' rather than `LaTeX2e', since the previous version of LaTeX (2.09) was frozen decades ago.

LaTeX is currently maintained by a group of volunteers (http://latex-project.org).  The official documentation written by the LaTeX project is available from their web site.  This document is completely unofficial and has not been reviewed by the LaTeX maintainers. Do not send bug reports or anything else about this document to them. Instead, please send all comments to LTXREFMAN_BUGS.

This document is a reference.  There is a vast array of other sources of information about LaTeX, at all levels.  Here are a few introductions.

http://ctan.org/pkg/latex-doc-ptr
     Two pages of recommended references to LaTeX documentation.

http://ctan.org/pkg/first-latex-doc
     Writing your first document, with a bit of both text and math.

http://ctan.org/pkg/usrguide
     The guide for document authors that is maintained as part of LaTeX. Many other guides by many other people are also available, independent of LaTeX itself; one such is the next item:

http://ctan.org/pkg/lshort
     A short introduction to LaTeX, translated to many languages.

http://tug.org/begin.html
     Introduction to the TeX system, including LaTeX, with further references.

Overview of LaTeX
*****************

LaTeX is a system for typesetting documents.  It was originally created by Leslie Lamport and is now maintained by a group of volunteers (http://latex-project.org).  It is widely used, particularly for complex and technical documents, such as those involving mathematics.

A LaTeX user writes an input file containing text along with interspersed commands, for instance commands describing how the text should be formatted.  It is implemented as a set of related commands that interface with Donald E. Knuth's TeX typesetting program (the technical term is that LaTeX is a macro package for the TeX engine).  The user produces the output document by giving that input file to the TeX engine.

The term LaTeX is also sometimes used to mean the language in which the document is marked up, that is, to mean the set of commands available to a LaTeX user.

The name LaTeX is short for ``Lamport TeX''.  It is pronounced LAH-teck or LAY-teck, or sometimes LAY-tecks.  Inside a document, produce the logo with \LaTeX.  Where use of the logo is not sensible, such as in plain text, write it as LaTeX.

Starting and ending
===================

old name

LaTeX files have a simple global structure, with a standard beginning and ending.  Here is a ``hello, world'' example:

     \documentclass{article}
     \begin{document}
     Hello, \LaTeX\ world.
     \end{document}

Here, the article is the so-called document class, implemented in a file article.cls.  Any document class can be used.  A few document classes are defined by LaTeX itself, and vast array of others are widely available.  See Document classes.

You can include other LaTeX commands between the \documentclass and the \begin{document} commands. This area is called the preamble.

The \begin{document} ... \end{document} is a so-called environment; the document environment (and no others) is required in all LaTeX documents (see document).  LaTeX provides many environments itself, and many more are defined separately. See Environments.

The following sections discuss how to produce PDF or other output from a LaTeX input file.

Output files
============

LaTeX produces a main output file and at least two accessory files. The main output file's name ends in either .dvi or .pdf.

.dvi
     If LaTeX is invoked with the system command latex then it produces a DeVice Independent file, with extension .dvi.  You can view this file with a command such as xdvi, or convert it to a PostScript .ps file with dvips or to a Portable Document Format .pdf file with dvipdfmx. The contents of the file can be dumped in human-readable form with dvitype.  A vast array of other DVI utility programs are available (http://mirror.ctan.org/dviware).

.pdf
     If LaTeX is invoked via the system command pdflatex, among other commands (see TeX engines), then the main output is a Portable Document Format (PDF) file.  Typically this is a self-contained file, with all fonts and images included.

LaTeX also produces at least two additional files.

.log
     This transcript file contains summary information such as a list of loaded packages.  It also includes diagnostic messages and perhaps additional information for any errors.

.aux
     Auxiliary information is used by LaTeX for things such as cross references.  For example, the first time that LaTeX finds a forward reference---a cross reference to something that has not yet appeared in the source---it will appear in the output as a doubled question mark ??.  When the referred-to spot does eventually appear in the source then LaTeX writes its location information to this .aux file.  On the next invocation, LaTeX reads the location information from this file and uses it to resolve the reference, replacing the double question mark with the remembered location.

LaTeX may produce yet more files, characterized by the filename ending.  These include a .lof file that is used to make a list of figures, a .lot file used to make a list of tables, and a .toc file used to make a table of contents.  A particular class may create others; the list is open-ended.

TeX engines
===========

LaTeX is defined to be a set of commands that are run by a TeX implementation (see Overview).  This section gives a terse overview of the main programs.

latex
pdflatex
     In TeX Live (http://tug.org/texlive), if LaTeX is invoked via either the system command latex or pdflatex, then the pdfTeX engine is run (http://ctan.org/pkg/pdftex). When invoked as latex, the main output is a .dvi file; as pdflatex, the main output is a .pdf file.

     pdfTeX incorporates the e-TeX extensions to Knuth's original program (http://ctan.org/pkg/etex), including additional programming features and bi-directional typesetting, and has plenty of extensions of its own.  e-TeX is available on its own as the system command etex, but this is plain TeX (and produces .dvi).

     In other TeX distributions, latex may invoke e-TeX rather than pdfTeX.  In any case, the e-TeX extensions can be assumed to be available in LaTeX.

lualatex
     If LaTeX is invoked via the system command lualatex, the LuaTeX engine is run (http://ctan.org/pkg/luatex).  This program allows code written in the scripting language Lua (http://luatex.org) to interact with TeX's typesetting. LuaTeX handles UTF-8 Unicode input natively, can handle OpenType and TrueType fonts, and produces a .pdf file by default. There is also dvilualatex to produce a .dvi file, but this is rarely used.

xelatex
     If LaTeX is invoked with the system command xelatex, the XeTeX engine is run (http://tug.org/xetex).  Like LuaTeX, XeTeX natively supports UTF-8 Unicode and TrueType and OpenType fonts, though the implementation is completely different, mainly using external libraries instead of internal code.  XeTeX produces a .pdf file as output; it does not support DVI output.

     Internally, XeTeX creates an .xdv file, a variant of DVI, and translates that to PDF using the (x)dvipdfmx program, but this process is automatic.  The .xdv file is only useful for debugging.

Other variants of LaTeX and TeX exist, e.g., to provide additional support for Japanese and other languages ([u]pTeX, http://ctan.org/pkg/ptex, http://ctan.org/pkg/uptex).

LaTeX command syntax
====================

In the LaTeX input file, a command name starts with a backslash character, \.  The name itself then consists of either (a) a string of letters or (b) a single non-letter.

LaTeX commands names are case sensitive so that \pagebreak differs from \Pagebreak (the latter is not a standard command). Most commands are lowercase, but in any event you must enter all commands in the same case as they are defined.

A command may be followed by zero, one, or more arguments. These arguments may be either required or optional.  Required arguments are contained in curly braces, {...}.  Optional arguments are contained in square brackets, [...].  Generally, but not universally, if the command accepts an optional argument, it comes first, before any required arguments.

Inside of an optional argument, to use the character close square bracket (]) hide it inside curly braces, as in \item[closing bracket {]}].  Similarly, if an optional argument comes last, with no required argument after it, then to make the first character of the following text be an open square bracket, hide it inside curly braces.

LaTeX has the convention that some commands have a * form that is related to the form without a *, such as \chapter and \chapter*.  The exact difference in behavior varies from command to command.

This manual describes all accepted options and *-forms for the commands it covers (barring unintentional omissions, a.k.a. bugs).

Environments
------------

Synopsis:

     \begin{ENVIRONMENT NAME}
       ...
     \end{ENVIRONMENT NAME}

An area of LaTeX source, inside of which there is a distinct behavior.  For instance, for poetry in LaTeX put the lines between \begin{verse} and \end{verse}.

     \begin{verse}
       There once was a man from Nantucket \\
       ...
     \end{verse}

See Environments for a list of environments.

The ENVIRONMENT NAME at the beginning must exactly match that at the end.  This includes the case where ENVIRONMENT NAME ends in a star (*); both the \begin and \end texts must include the star.

Environments may have arguments, including optional arguments.  This example produces a table.  The first argument is optional (and causes the table to be aligned on its top row) while the second argument is required (it specifies the formatting of columns).

     \begin{tabular}[t]{r|l}
       ... rows of table ...
     \end{tabular}

Command declarations
--------------------

A command that changes the value, or changes the meaning, of some other command or parameter.  For instance, the \mainmatter command changes the setting of page numbers from roman numerals to arabic.

\makeatletter and \makeatother
------------------------------

Synopsis:

     \makeatletter
       ... definition of commands with @ in their name ..
     \makeatother

Used to redefine internal LaTeX commands.  \makeatletter makes the at-sign character @ have the category code of a letter, 11.  \makeatother sets the category code of @ to 12, its original value.

As each character is read by TeX for LaTeX, it is assigned a character category code, or catcode for short. For instance, the backslash \ is assigned the catcode 0, for characters that start a command.  These two commands alter the catcode assigned to @.

The alteration is needed because many of LaTeX's commands use @ in their name, to prevent users from accidentally defining a command that replaces one of LaTeX's own.  Command names consist of a category 0 character, ordinarily backslash, followed by letters, category 11 characters (except that a command name can also consist of a category 0 character followed by a single non-letter symbol). So under the default category codes, user-defined commands cannot contain an @.  But \makeatletter and \makeatother allow users to define or redefine commands named with @.

Use these two commands inside a .tex file, in the preamble, when defining or redefining a command with @ in its name.  Don't use them inside .sty or .cls files since the \usepackage and \documentclass commands set the at sign to have the character code of a letter.

For a comprehensive list of macros with an at-sign in their names see http://ctan.org/pkg/macros2e. These macros are mainly intended to package or class authors.

The example below is typical.  In the user's class file is a command \thesis@universityname.  The user wants to change the definition.  These three lines should go in the preamble, before the \begin{document}.

     \makeatletter
     \renewcommand{\thesis@universityname}{Saint Michael's College}
     \makeatother

\@ifstar
........

Synopsis:

     \newcommand{\mycmd}{\@ifstar{\mycmd@star}{\mycmd@nostar}}
     \newcommand{\mycmd@nostar}[NON-STARRED COMMAND NUMBER OF ARGS]{BODY OF NON-STARRED COMMAND}
     \newcommand{\mycmd@star}[STARRED COMMAND NUMBER OF ARGS]{BODY OF STARRED COMMAND}

Many standard LaTeX environments or commands have a variant with the same name but ending with a star character *, an asterisk. Examples are the table and table* environments and the \section and \section* commands.

When defining environments, following this pattern is straightforward because \newenvironment and \renewenvironment allow the environment name to contain a star.  For commands the situation is more complex.  As in the synopsis above, there will be a user-called command, given above as \mycmd, which peeks ahead to see if it is followed by a star.  For instance, LaTeX does not really have a \section* command; instead, the \section command peeks ahead.  This command does not accept arguments but instead expands to one of two commands that do accept arguments.  In the synopsis these two are \mycmd@nostar and \mycmd@star.  They could take the same number of arguments or a different number, or no arguments at all. As always, in a LaTeX document a command using at-sign @ must be enclosed inside a \makeatletter ... \makeatother block (see \makeatletter and \makeatother).

This example of \@ifstar defines the command \ciel and a variant \ciel*.  Both have one required argument.  A call to \ciel{night} will return "starry night sky" while \ciel*{blue} will return "starry not blue sky".

     \newcommand*{\ciel@unstarred}[1]{starry #1 sky}
     \newcommand*{\ciel@starred}[1]{starry not #1 sky}
     \newcommand*{\ciel}{\@ifstar{\ciel@starred}{\ciel@unstarred}}

In the next example, the starred variant takes a different number of arguments than does the unstarred one.  With this definition, Agent 007's ``My name is \agentsecret*{Bond}, \agentsecret{James}{Bond}.'' is equivalent to ``My name is \textsc{Bond}, \textit{James} textsc{Bond}.''

     \newcommand*{\agentsecret@unstarred}[2]{\textit{#1} \textsc{#2}}
     \newcommand*{\agentsecret@starred}[1]{\textsc{#1}}
     \newcommand*{\agentsecret}{\@ifstar{\agentsecret@starred}{\agentsecret@unstarred}}

There are two sometimes more convenient ways to accomplish the work of \@ifstar.  The suffix package allows the construct \newcommand\mycommand{UNSTARRED VERSION} followed by \WithSuffix\newcommand\mycommand*{STARRED VERSION}.  And LaTeX3 has the xparse package that allows this code.

     \NewDocumentCommand\foo{s}{\IfBooleanTF#1
       {STARRED VERSION}%
       {UNSTARRED VERSION}%
       }

Document classes
****************

The document's overall class is defined with this command, which is normally the first command in a LaTeX source file.

     \documentclass[OPTIONS]{CLASS}

The following document CLASS names are built into LaTeX. (Many other document classes are available as separate packages; see Overview.)

article
     For a journal article, a presentation, and miscellaneous general use.

book
     Full-length books, including chapters and possibly including front matter, such as a preface, and back matter, such as an appendix (see Front/back matter).

letter
     Mail, optionally including mailing labels (see Letters).

report
     For documents of length between an article and a book, such as technical reports or theses, which may contain several chapters.

slides
     For slide presentations---rarely used today.  In its place the beamer package is perhaps the most prevalent (see beamer template).

Standard OPTIONS are described in the next section.

Document class options
======================

You can specify so-called global options or class options to the \documentclass command by enclosing them in square brackets. To specify more than one OPTION, separate them with a comma, as in:

     \documentclass[OPTION1,OPTION2,...]{CLASS}

Here is the list of the standard class options.

All of the standard classes except slides accept the following options for selecting the typeface size (default is 10pt):

     10pt  11pt  12pt

All of the standard classes accept these options for selecting the paper size (these show height by width):

a4paper
     210 by 297mm (about 8.25 by 11.75 inches)

a5paper
     148 by 210mm (about 5.8 by 8.3 inches)

b5paper
     176 by 250mm (about 6.9 by 9.8 inches)

executivepaper
     7.25 by 10.5 inches

legalpaper
     8.5 by 14 inches

letterpaper
     8.5 by 11 inches (the default)

When using one of the engines pdfLaTeX, LuaLaTeX, or XeLaTeX (see TeX engines), options other than letterpaper set the print area but you must also set the physical paper size.  One way to do that is to put \pdfpagewidth=\paperwidth and \pdfpageheight=\paperheight in your document's preamble.

The geometry package provides flexible ways of setting the print area and physical page size.

Miscellaneous other options:

draft
final
     Mark (draft) or do not mark (final) overfull boxes with a black box in the margin; default is final.

fleqn
     Put displayed formulas flush left; default is centered.

landscape
     Selects landscape format; default is portrait.

leqno
     Put equation numbers on the left side of equations; default is the right side.

openbib
     Use ``open'' bibliography format.

titlepage
notitlepage
     Specifies whether there is a separate page for the title information and for the abstract also, if there is one.  The default for the report class is titlepage, for the other classes it is notitlepage.

The following options are not available with the slides class.

onecolumn
twocolumn
     Typeset in one or two columns; default is onecolumn.

oneside
twoside
     Selects one- or two-sided layout; default is oneside, except that in the book class the default is twoside.

     For one-sided printing, the text is centered on the page.  For two-sided printing, the \evensidemargin (\oddsidemargin) parameter determines the distance on even (odd) numbered pages between the left side of the page and the text's left margin, with \oddsidemargin being 40% of the difference between \paperwidth and \textwidth, and \evensidemargin is the remainder.

openright
openany
     Determines if a chapter should start on a right-hand page; default is openright for book, and openany for report.

The slides class offers the option clock for printing the time at the bottom of each note.

Additional packages
===================

Load a package PKG, with the package options given in the comma-separated list OPTIONS, as here.

     \usepackage[OPTIONS]{PKG}.

To specify more than one package you can separate them with a comma, as in \usepackage{PKG1,PKG2,...}, or use multiple \usepackage commands.

Any options given in the \documentclass command that are unknown to the selected document class are passed on to the packages loaded with \usepackage.

Class and package construction
==============================

You can create new document classes and new packages.  For instance, if your memos must satisfy some local requirements, such as a standard header for each page, then you could create a new class smcmemo.cls and begin your documents with \documentclass{smcmemo}.

What separates a package from a document class is that the commands in a package are useful across classes while those in a document class are specific to that class.  Thus, a command to set page headers is for a package while a command to make the page headers say Memo from the SMC Math Department is for a class.

Inside of a class or package file you can use the at-sign @ as a character in command names without having to surround the code containing that command with \makeatletter and \makeatother.  See \makeatletter and \makeatother. This allow you to create commands that users will not accidentally redefine. Another technique is to preface class- or package-specific commands with some string to prevent your class or package from interfering with others. For instance, the class smcmemo might have commands \smc@tolist, \smc@fromlist, etc.

Class and package structure
---------------------------

A class file or package file typically has four parts.

     In the identification part, the file says that it is a LaTeX package or class and describes itself, using the \NeedsTeXFormat and \ProvidesClass or \ProvidesPackage commands.

 1. The preliminary declarations part declares some commands and can also load other files. Usually these commands will be those needed for the code used in the next part.  For example, an smcmemo class might be called with an option to read in a file with a list of people for the to-head, as \documentclass[mathto]{smcmemo}, and therefore needs to define a command \newcommand{\setto}[1]{\def\@tolist{#1}} used in that file.

 2. In the handle options part the class or package declares and processes its options.  Class options allow a user to start their document as \documentclass[OPTION LIST]{CLASS NAME}, to modify the behavior of the class.  An example is when you declare \documentclass[11pt]{article} to set the default document font size.

 3. Finally, in the more declarations part the class or package usually does most of its work: declaring new variables, commands and fonts, and loading other files.

Here is a starting class file, which should be saved as stub.cls where LaTeX can find it, for example in the same directory as the .tex file.

     \NeedsTeXFormat{LaTeX2e}
     \ProvidesClass{stub}[2017/07/06 stub to start building classes from]
     \DeclareOption*{\PassOptionsToClass{\CurrentOption}{article}}
     \ProcessOptions\relax
     \LoadClass{article}

It identifies itself, handles the class options via the default of passing them all to the article class, and then loads the article class to provide the basis for this class's code.

For more, see the official guide for class and package writers, the Class Guide, at http://www.latex-project.org/help/documentation/clsguide.pdf (much of the descriptions here derive from this document), or the tutorial https://www.tug.org/TUGboat/tb26-3/tb84heff.pdf.

Class and package commands
--------------------------

These are the commands designed to help writers of classes or packages.

\AtBeginDvi{specials}
     Save in a box register things that are written to the .dvi file at the beginning of the shipout of the first page of the document.

\AtEndOfClass{CODE}

\AtEndOfPackage{CODE}
     Hook to insert CODE to be executed when LaTeX finishes processing the current class or package.  You can use these hooks multiple times; the code will be executed in the order that you called it.  See also \AtBeginDocument.

\CheckCommand{CMD}[NUM][DEFAULT]{DEFINITION}

\CheckCommand*{CMD}[NUM][DEFAULT]{DEFINITION}
     Like \newcommand (see \newcommand & \renewcommand) but does not define CMD; instead it checks that the current definition of CMD is exactly as given by DEFINITION and is or is not long as expected.  A long command is a command that accepts \par within an argument.  The CMD command is expected to be long with the unstarred version of \CheckCommand.  Raises an error when the check fails.  This allows you to check before you start redefining cmd yourself that no other package has already redefined this command.

\ClassError{CLASS NAME}{ERROR TEXT}{HELP TEXT}

\PackageError{PACKAGE NAME}{ERROR TEXT}{HELP TEXT}

\ClassWarning{CLASS NAME}{WARNING TEXT}

\PackageWarning{PACKAGE NAME}{WARNING TEXT}

\ClassWarningNoLine{CLASS NAME}{WARNING TEXT}

\PackageWarningNoLine{PACKAGE NAME}{WARNING TEXT}

\ClassInfo{CLASS NAME}{INFO TEXT}

\PackageInfo{PACKAGE NAME}{INFO TEXT}

\ClassInfoNoLine{CLASS NAME}{INFO TEXT}

\PackageInfoNoLine{PACKAGE NAME}{INFO TEXT}
     Produce an error message, or warning or informational messages.

     For \ClassError and \PackageError the message is ERROR TEXT, followed by TeX's ? error prompt. If the user then asks for help by typing h, they see the HELP TEXT.

     The four warning commands are similar except that they write WARNING TEXT on the screen with no error prompt.  The four info commands write INFO TEXT only in the transcript file.  The NoLine versions do not show the number of the line generating the message, while the other versions do show that number.

     To format the messages, including the HELP TEXT: use \protect to stop a command from expanding, get a line break with \MessageBreak, and get a space with \space when a space character does not allow it, like after a command.  Note that LaTeX appends a period to the messages.

\CurrentOption
     Expands to the name of the currently-being-processed option.  Can only be used within the CODE argument of either \DeclareOption or \DeclareOption*.

\DeclareOption{OPTION}{CODE}

\DeclareOption*{CODE}
     Make an option available to a user, for invoking in their \documentclass command.  For example, the smcmemo class could have an option allowing users to put the institutional logo on the first page with \documentclass[logo]{smcmemo}.  The class file must contain \DeclareOption{logo}{CODE} (and later, \ProcessOptions).

     If you request an option that has not been declared, by default this will produce a warning like Unused global option(s): [badoption]. Change this behaviour with the starred version \DeclareOption*{CODE}.  For example, many classes extend an existing class, using a declaration such as \LoadClass{article}, and for passing extra options to the underlying class use code such as this.

          \DeclareOption*{%
          \PassOptionsToClass{\CurrentOption}{article}%
          }

     Another example is that the class smcmemo may allow users to keep lists of memo recipients in external files.  Then the user could invoke \documentclass[math]{smcmemo} and it will read the file math.memo.  This code handles the file if it exists and otherwise passes the option to the article class.

          \DeclareOption*{\InputIfFileExists{\CurrentOption.memo}{}{%
              \PassOptionsToClass{\CurrentOption}{article}}}

\DeclareRobustCommand{CMD}[NUM][DEFAULT]{DEFINITION}

\DeclareRobustCommand*{CMD}[NUM][DEFAULT]{DEFINITION}
     Like \newcommand and \newcommand* (see \newcommand & \renewcommand) but these declare a robust command, even if some code within the DEFINITION is fragile.  (For a discussion of robust and fragile commands see \protect.) Use this command to define new robust commands or to redefine existing commands and make them robust. Unlike \newcommand these do not give an error if macro CMD already exists; instead, a log message is put into the transcript file if a command is redefined.

     Commands defined this way are a bit less efficient than those defined using \newcommand so unless the command's data is fragile and the command is used within a moving argument, use \newcommand.

     The etoolbox package offers commands \newrobustcmd, \newrobustcmd*, \renewrobustcmd, \renewrobustcmd*, \providerobustcmd, and \providerobustcmd* which are similar to \newcommand, \newcommand*, \renewcommand, \renewcommand*, \providecommand, and \providecommand*, but define a robust CMD with two advantages as compared to \DeclareRobustCommand:

      1. They use the low-level e-TeX protection mechanism rather than the higher level LaTeX \protect mechanism, so they do not incur the slight loss of performance mentioned above, and

      2. They make the same distinction between \new..., \renew..., and \provide..., as the standard commands, so they do not just make a log message when you redefine CMD that already exists, in that case you need to use either \renew... or \provide... or you get an error.

\IfFileExists{FILE NAME}{TRUE CODE}{FALSE CODE}

\InputIfFileExists{FILE NAME}{TRUE CODE}{FALSE CODE}
     Execute TRUE CODE if LaTeX can find the file FILE NAME and FALSE CODE otherwise.  In the second case it inputs the file immediately after executing TRUE CODE.  Thus \IfFileExists{img.pdf}{\includegraphics{img.pdf}}{\typeout{WARNING: img.pdf not found}} will include the graphic img.pdf if it is found but otherwise just give a warning.

     This command looks for the file in all search paths that LaTeX uses, not only in the current directory.  To look only in the current directory do something like \IfFileExists{./filename}{TRUE CODE}{FALSE CODE}.  If you ask for a filename without a .tex extension then LaTeX will first look for the file by appending the .tex; for more on how LaTeX handles file extensions see \input.

\LoadClass[OPTIONS LIST]{CLASS NAME}[RELEASE DATE]

\LoadClassWithOptions{CLASS NAME}[RELEASE DATE]
     Load a class, as with \documentclass[OPTIONS LIST]{CLASS NAME}[RELEASE INFO].  An example is \LoadClass[twoside]{article}.

     The OPTIONS LIST, if present, is a comma-separated list.  The RELEASE DATE is optional.  If present it must have the form YYYY/MM/DD.

     If you request a RELEASE DATE and the date of the package installed on your system is earlier, then you get a warning on the screen and in the log like You have requested, on input line 4, version `2038/01/19' of document class article, but only version `2014/09/29 v1.4h Standard LaTeX document class' is available.

     The command version \LoadClassWithOptions uses the list of options for the current class.  This means it ignores any options passed to it via \PassOptionsToClass.  This is a convenience command that lets you build classes on existing ones, such as the standard article class, without having to track which options were passed.

\ExecuteOptions{OPTIONS-LIST}
     For each option OPTION in the OPTIONS-LIST, in order, this command executes the command \ds@OPTION.  If this command is not defined then that option is silently ignored.

     It can be used to provide a default option list before \ProcessOptions.  For example, if in a class file you want the default to be 11pt fonts then you could specify \ExecuteOptions{11pt}\ProcessOptions\relax.

\NeedsTeXFormat{FORMAT}[FORMAT DATE]
     Specifies the format that this class must be run under.  Often issued as the first line of a class file, and most often used as: \NeedsTeXFormat{LaTeX2e}.  When a document using that class is processed, the format name given here must match the format that is actually being run (including that the FORMAT string is case sensitive).  If it does not match then execution stops with an error like This file needs format `LaTeX2e' but this is `xxx'.

     To specify a version of the format that you know to have certain features, include the optional FORMAT DATE on which those features were implemented.  If present it must be in the form YYYY/MM/DD. If the format version installed on your system is earlier than FORMAT DATE then you get a warning like You have requested release `2038/01/20' of LaTeX, but only release `2016/02/01' is available.

\OptionNotUsed
     Adds the current option to the list of unused options.  Can only be used within the CODE argument of either \DeclareOption or \DeclareOption*.

\PassOptionsToClass{OPTION LIST}{CLASS NAME}

\PassOptionsToPackage{OPTION LIST}{PACKAGE NAME}
     Adds the options in the comma-separated list OPTION LIST to the options used by any future \RequirePackage or \usepackage command for package PACKAGE NAME or the class CLASS NAME.

     The reason for these commands is: you may load a package any number of times with no options but if you want options then you may only supply them when you first load the package.  Loading a package with options more than once will get you an error like Option clash for package foo. (LaTeX throws an error even if there is no conflict between the options.)

     If your own code is bringing in a package twice then you can collapse that to once, for example replacing the two \RequirePackage[landscape]{geometry}\RequirePackage[margins=1in]{geometry} with the single \RequirePackage[landscape,margins=1in]{geometry}.  But if you are loading a package that in turn loads another package then you need to queue up the options you desire for this other package.  For instance, suppose the package foo loads the package geometry.  Instead of \RequirePackage{foo}\RequirePackage[draft]{graphics} you must write \PassOptionsToPackage{draft}{graphics} \RequirePackage{foo}.  (If foo.sty loads an option in conflict with what you want then you may have to look into altering its source.)

     These commands are useful for general users as well as class and package writers.  For instance, suppose a user wants to load the graphicx package with the option draft and also wants to use a class foo that loads the graphicx package, but without that option. The user could start their LaTeX file with \PassOptionsToPackage{draft}{graphicx}\documentclass{foo}.

\ProcessOptions

\ProcessOptions*\@OPTIONS
     Execute the code for each option that the user has invoked.  Include it in the class file as \ProcessOptions\relax (because of the existence of the starred command).

     Options come in two types.  Local options have been specified for this particular package in the OPTIONS argument of \PassOptionsToPackage{OPTIONS}, \usepackage[OPTIONS], or \RequirePackage[OPTIONS].  Global options are those given by the class user in \documentclass[OPTIONS] (If an option is specified both locally and globally then it is local.)

     When \ProcessOptions is called for a package pkg.sty, the following happens:

      1. For each option OPTION so far declared with \DeclareOption, it looks to see if that option is either a global or a local option for pkg. If so then it executes the declared code.  This is done in the order in which these options were given in pkg.sty.

      2. For each remaining local option, it executes the command \ds@OPTION if it has been defined somewhere (other than by a \DeclareOption); otherwise, it executes the default option code given in \DeclareOption*. If no default option code has been declared then it gives an error message.  This is done in the order in which these options were specified.

     When \ProcessOptions is called for a class it works in the same way except that all options are local, and the default CODE for \DeclareOption* is \OptionNotUsed rather than an error.

     The starred version \ProcessOptions* executes the options in the order specified in the calling commands, rather than in the order of declaration in the class or package. For a package this means that the global options are processed first.

\ProvidesClass{CLASS NAME}[RELEASE DATE BRIEF ADDITIONAL INFORMATION]

\ProvidesClass{CLASS NAME}[RELEASE DATE]

\ProvidesPackage{PACKAGE NAME}[RELEASE DATE BRIEF ADDITIONAL INFORMATION]

\ProvidesPackage{PACKAGE NAME}[RELEASE DATE]
     Identifies the class or package, printing a message to the screen and the log file.

     When a user writes \documentclass{smcmemo} then LaTeX loads the file smcmemo.cls.  Similarly, a user writing \usepackage{test} prompts LaTeX to load the file test.sty.  If the name of the file does not match the declared class or package name then you get a warning.  Thus, if you invoke \documentclass{smcmemo}, and the file smcmemo.cls has the statement \ProvidesClass{xxx} then you get a warning like You have requested document class `smcmemo', but the document class provides 'xxx'.  This warning does not prevent LaTeX from processing the rest of the class file normally.

     If you include the optional argument, then you must include the date, before the first space if any, and it must have the form YYYY/MM/DD. The rest of the optional argument is free-form, although it traditionally identifies the class, and is written to the screen during compilation and to the log file.  Thus, if your file smcmemo.cls contains the line \ProvidesClass{smcmemo}[2008/06/01 v1.0 SMC memo class] and your document's first line is \documentclass{smcmemo} then you will see Document Class: smcmemo 2008/06/01 v1.0 SMC memo class.

     The date in the optional argument allows class and package users to ask to be warned if the version of the class or package installed on their system is earlier than RELEASE DATE, by using the optional arguments such as \documentclass{smcmemo}[2018/10/12] or \usepackage{foo}[[2017/07/07]].  (Note that package users only rarely include a date, and class users almost never do.)

\ProvidesFile{FILE NAME}[ADDITIONAL INFORMATION]
     Declare a file other than the main class and package files, such as configuration files or font definition files.  Put this command in that file and you get in the log a string like File: test.config 2017/10/12 config file for test.cls for FILE NAME equal to test.config and ADDITIONAL INFORMATION equal to 2017/10/12 config file for test.cls.

\RequirePackage[OPTION LIST]{PACKAGE NAME}[RELEASE DATE]

\RequirePackageWithOptions{PACKAGE NAME}[RELEASE DATE]
     Load a package, like the document author command \usepackage. See Additional packages. An example is \RequirePackage[landscape,margin=1in]{geometry}.  Note that the LaTeX development team strongly recommends use of these commands over Plain TeX's \input; see the Class Guide.

     The OPTION LIST, if present, is a comma-separated list.  The RELEASE DATE, if present, must have the form YYYY/MM/DD.  If the release date of the package as installed on your system is earlier than RELEASE DATE then you get a warning like You have requested, on input line 9, version `2017/07/03' of package jhtest, but only version `2000/01/01' is available.

     The \RequirePackageWithOptions version uses the list of options for the current class.  This means it ignores any options passed to it via \PassOptionsToClass.  This is a convenience command to allow easily building classes on existing ones without having to track which options were passed.

     The difference between \usepackage and \RequirePackage is small.  The \usepackage command is intended for the document file while \RequirePackage is intended for package and class files. Thus, using \usepackage before the \documentclass command causes LaTeX to give error like \usepackage before \documentclass, but you can use \RequirePackage there.

Fonts
*****

old name

Two important aspects of selecting a font are specifying a size and a style.  The LaTeX commands for doing this are described here.

Font styles
===========

The following type style commands are supported by LaTeX.

This first group of commands is typically used with an argument, as in \textit{TEXT}.  In the table below, the corresponding command in parenthesis is the ``declaration form'', which takes no arguments, as in {\itshape TEXT}.  The scope of the declaration form lasts until the next type style command or the end of the current group.

These commands, in both the argument form and the declaration form, are cumulative; e.g., you can say either \sffamily\bfseries or \bfseries\sffamily to get bold sans serif.

You can alternatively use an environment form of the declarations; for instance, \begin{ttfamily}...\end{ttfamily}.

These font-switching commands automatically insert italic corrections if needed.  (see \/, for the details of italic corrections.) Specifically, they insert the italic correction unless the following character is in the list \nocorrlist, which by default consists of a period and a comma.  To suppress the automatic insertion of italic correction, use \nocorr at the start or end of the command argument, such as \textit{\nocorr text} or \textsc{text \nocorr}.

\textrm (\rmfamily)
     Roman.

\textit (\itshape)
     Italics.

\textmd (\mdseries)
     Medium weight (default).

\textbf (\bfseries)
     Boldface.

\textup (\upshape)
     Upright (default).

\textsl (\slshape)
     Slanted.

\textsf (\sffamily)
     Sans serif.

\textsc (\scshape)
     Small caps.

\texttt (\ttfamily)
     Typewriter.

\textnormal (\normalfont)
     Main document font.

Although it also changes fonts, the \emph{TEXT} command is semantic, for text to be emphasized, and should not be used as a substitute for \textit.  For example, \emph{START TEXT \emph{MIDDLE TEXT} END TEXT} will result in the START TEXT and END TEXT in italics, but MIDDLE TEXT will be in roman.

LaTeX also provides the following commands, which unconditionally switch to the given style, that is, are not cumulative.  Also, they are used differently than the above commands: {\CMD...} instead of \CMD{...}.  These are two unrelated constructs.

\bf
     Switch to bold face.

\cal
     Switch to calligraphic letters for math.

\it
     Italics.

\rm
     Roman.

\sc
     Small caps.

\sf
     Sans serif.

\sl
     Slanted (oblique).

\tt
     Typewriter (monospace, fixed-width).

The \em command is the unconditional version of \emph.

(Some people consider the unconditional font-switching commands, such as \tt, obsolete and that only the cumulative commands (\texttt) should be used.  Others think that both sets of commands have their place and sometimes an unconditional font switch is precisely what you want; for one example, see description.)

The following commands are for use in math mode.  They are not cumulative, so \mathbf{\mathit{SYMBOL}} does not create a boldface and italic SYMBOL; instead, it will just be in italics.  This is because typically math symbols need consistent typographic treatment, regardless of the surrounding environment.

\mathrm
     Roman, for use in math mode.

\mathbf
     Boldface, for use in math mode.

\mathsf
     Sans serif, for use in math mode.

\mathtt
     Typewriter, for use in math mode.

\mathit
(\mit)
     Italics, for use in math mode.

\mathnormal
     For use in math mode, e.g., inside another type style declaration.

\mathcal
     Calligraphic letters, for use in math mode.

In addition, the command \mathversion{bold} can be used for switching to bold letters and symbols in formulas. \mathversion{normal} restores the default.

Finally, the command \oldstylenums{NUMERALS} will typeset so-called ``old-style'' numerals, which have differing heights and depths (and sometimes widths) from the standard ``lining'' numerals, which all have the same height as uppercase letters.  LaTeX's default fonts support this, and will respect \textbf (but not other styles; there are no italic old-style numerals in Computer Modern).  Many other fonts have old-style numerals also; sometimes the textcomp package must be loaded, and sometimes package options are provided to make them the default.  FAQ entry: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=osf.

Font sizes
==========

The following standard type size commands are supported by LaTeX. The table shows the command name and the corresponding actual font size used (in points) with the 10pt, 11pt, and 12pt document size options, respectively (see Document class options).

Command    10pt    11pt    12pt
\tiny
5            6            6
\scriptsize
7            8            8
\footnotesize
8            9            10
\small
9            10           10.95
\normalsize (default)
10           10.95        12
\large
12           12           14.4
\Large
14.4         14.4         17.28
\LARGE
17.28        17.28        20.74
\huge
20.74        20.74        24.88
\Huge
24.88        24.88        24.88

The commands as listed here are ``declaration forms''. The scope of the declaration form lasts until the next type style command or the end of the current group.  You can also use the environment form of these commands; for instance, \begin{tiny}...\end{tiny}.

Low-level font commands
=======================

These commands are primarily intended for writers of macros and packages.  The commands listed here are only a subset of the available ones.

\fontencoding{ENCODING}
     Select the font encoding, the encoding of the output font. There are a large number of valid encodings.  The most common are OT1, Knuth's original encoding for Computer Modern (the default), and T1, also known as the Cork encoding, which has support for the accented characters used by the most widespread European languages (German, French, Italian, Polish and others), which allows TeX to hyphenate words containing accented letters. For more, see https://ctan.org/pkg/encguide.

\fontfamily{FAMILY}
     Select the font family.  The web page http://www.tug.dk/FontCatalogue/ provides one way to browse through many of the fonts easily used with LaTeX.  Here are examples of some common families:

     pag
     Avant Garde
     fvs
     Bitstream Vera Sans
     pbk
     Bookman
     bch
     Charter
     ccr
     Computer Concrete
     cmr
     Computer Modern
     cmss
     Computer Modern Sans Serif
     cmtt
     Computer Modern Typewriter
     pcr
     Courier
     phv
     Helvetica
     fi4
     Inconsolata
     lmr
     Latin Modern
     lmss
     Latin Modern Sans
     lmtt
     Latin Modern Typewriter
     pnc
     New Century Schoolbook
     ppl
     Palatino
     ptm
     Times
     uncl
     Uncial
     put
     Utopia
     pzc
     Zapf Chancery

\fontseries{SERIES}
     Select the font series.  A series combines a weight and a width.  Typically, a font supports only a few of the possible combinations.  Some common combined series values include:

     m
     Medium (normal)
     b
     Bold
     c
     Condensed
     bc
     Bold condensed
     bx
     Bold extended

     The possible values for weight, individually, are:

     ul
     Ultra light
     el
     Extra light
     l
     Light
     sl
     Semi light
     m
     Medium (normal)
     sb
     Semi bold
     b
     Bold
     eb
     Extra bold
     ub
     Ultra bold

     The possible values for width, individually, are (the meaning and relationship of these terms varies with individual typefaces):

     uc
     Ultra condensed
     ec
     Extra condensed
     c
     Condensed
     sc
     Semi condensed
     m
     Medium
     sx
     Semi expanded
     x
     Expanded
     ex
     Extra expanded
     ux
     Ultra expanded

     When forming the SERIES string from the weight and width, drop the m that stands for medium weight or medium width, unless both weight and width are m, in which case use just one (m).

\fontshape{SHAPE}
     Select font shape. Valid shapes are:

     n
     Upright (normal)
     it
     Italic
     sl
     Slanted (oblique)
     sc
     Small caps
     ui
     Upright italics
     ol
     Outline

     The two last shapes are not available for most font families, and small caps are often missing as well.

\fontsize{SIZE}{SKIP}
     Set the font size and the line spacing.  The unit of both parameters defaults to points (pt).  The line spacing is the nominal vertical space between lines, baseline to baseline.  It is stored in the parameter \baselineskip.  The default \baselineskip for the Computer Modern typeface is 1.2 times the \fontsize. Changing \baselineskip directly is inadvisable since its value is reset every time a size change happens; see \baselinestretch, next.

\baselinestretch
     LaTeX multiplies the line spacing by the value of the \baselinestretch parameter; the default factor is 1.  A change takes effect when \selectfont (see below) is called.  You can make a line skip change happen for the entire document, for instance doubling it, by doing \renewcommand{\baselinestretch}{2.0} in the preamble.

     However, the best way to double-space a document is to use the setspace package.  In addition to offering a number of spacing options, this package keeps the line spacing single-spaced in places where that is typically desirable, such as footnotes and figure captions.  See the package documentation.

\linespread{FACTOR}
     Equivalent to \renewcommand{\baselinestretch}{FACTOR}, and therefore must be followed by \selectfont to have any effect. Best specified in the preamble, or use the setspace package, as just described.

\selectfont
     The effects of the font commands described above do not happen until \selectfont is called, as in \fontfamily{FAMILYNAME}\selectfont.  It is often useful to put this in a macro:

     \newcommand*{\myfont}{\fontfamily{FAMILYNAME}\selectfont}

     (see \newcommand & \renewcommand).

\usefont{ENC}{FAMILY}{SERIES}{SHAPE}
     The same as invoking \fontencoding, \fontfamily, \fontseries and \fontshape with the given parameters, followed by \selectfont.  For example:

          \usefont{ot1}{cmr}{m}{n}

Layout
******

Commands for controlling the general page layout.

\onecolumn
==========

Start a new page and produce single-column output.  If the document is given the class option onecolumn then this is the default behavior (see Document class options).

This command is fragile (see \protect).

\twocolumn
==========

Synopses:

     \twocolumn
     \twocolumn[PRELIM ONE COLUMN TEXT]

Start a new page and produce two-column output. If the document is given the class option twocolumn then this is the default (see Document class options).

If the optional PRELIM ONE COLUMN TEXT argument is present, it is typeset in one-column mode before the two-column typesetting starts.

This command is fragile (see \protect).

These parameters control typesetting in two-column output:

\columnsep
     The distance between columns. The default is 35pt.  Change it with a command such as \setlength{\columnsep}{40pt} You must change it before the two column environment starts; in the preamble is a good place.

\columnseprule
     The width of the rule between columns. The rule appears halfway between the two columns.  The default is 0pt, meaning that there is no rule. Change it with a command such as \setlength{\columnseprule}{0.4pt}, before the two-column environment starts.

\columnwidth
     The width of a single column.  In one-column mode this is equal to \textwidth.  In two-column mode by default LaTeX sets the width of each of the two columns to be half of \textwidth minus \columnsep.

In a two-column document, the starred environments table* and figure* are two columns wide, whereas the unstarred environments table and figure take up only one column (see figure and see table). LaTeX places starred floats at the top of a page. The following parameters control float behavior of two-column output.

\dbltopfraction
     The maximum fraction at the top of a two-column page that may be occupied by two-column wide floats.  The default is 0.7, meaning that the height of a table* or figure* environment must not exceed 0.7\textheight .  If the height of your starred float environment exceeds this then you can take one of the following actions to prevent it from floating all the way to the back of the document:

       * Use the [tp] location specifier to tell LaTeX to try to put the bulky float on a page by itself, as well as at the top of a page.

       * Use the [t!] location specifier to override the effect of \dbltopfraction for this particular float.

       * Increase the value of \dbltopfraction to a suitably large number, to avoid going to float pages so soon.

     You can redefine it, for instance with \renewcommand{\dbltopfraction}{0.9}.

\dblfloatpagefraction
     For a float page of two-column wide floats, this is the minimum fraction that must be occupied by floats, limiting the amount of blank space. LaTeX's default is 0.5.  Change it with \renewcommand.

\dblfloatsep
     On a float page of two-column wide floats, this length is the distance between floats, at both the top and bottom of the page.  The default is 12pt plus2pt minus2pt for a document set at 10pt or 11pt, and 14pt plus2pt minus4pt for a document set at 12pt.

\dbltextfloatsep
     This length is the distance between a multi-column float at the top or bottom of a page and the main text.  The default is 20pt plus2pt minus4pt.

\dbltopnumber
     On a float page of two-column wide floats, this counter gives the maximum number of floats allowed at the top of the page.  The LaTeX default is 2.

This example uses \twocolumn's optional argument of to create a title that spans the two-column article:

     \documentclass[twocolumn]{article}
     \newcommand{\authormark}[1]{\textsuperscript{#1}}
     \begin{document}
     \twocolumn[{% inside this optional argument goes one-column text
       \centering
       \LARGE The Title \\[1.5em]
       \large Author One\authormark{1},
              Author Two\authormark{2},
              Author Three\authormark{1} \\[1em]
       \normalsize
       \begin{tabular}{p{.2\textwidth}@{\hspace{2em}}p{.2\textwidth}}
         \authormark{1}Department one  &\authormark{2}Department two \\
          School one                   &School two
       \end{tabular}\\[3em] % space below title part
       }]

     Two column text here.

\flushbottom
============

Make all pages in the documents after this declaration have the same height, by stretching the vertical space where necessary to fill out the page.  This is most often used when making two-sided documents since the differences in facing pages can be glaring.

If TeX cannot satisfactorily stretch the vertical space in a page then you get a message like Underfull \vbox (badness 10000) has occurred while \output is active.  If you get that, one option is to change to \raggedbottom (see \raggedbottom).  Alternatively, you can adjust the textheight to make compatible pages, or you can add some vertical stretch glue between lines or between paragraphs, as in \setlength{\parskip}{0ex plus0.1ex}.  Your last option is to, in a final editing stage, adjust the height of individual pages (see \enlargethispage).

The \flushbottom state is the default only if you select the twoside document class option (see Document class options).

\raggedbottom
=============

Make all later pages the natural height of the material on that page; no rubber vertical lengths will be stretched.  Thus, in a two-sided document the facing pages may be different heights.  This command can go at any point in the document body.  See \flushbottom.

This is the default unless you select the twoside document class option (see Document class options).

Page layout parameters
======================

\columnsep
\columnseprule
\columnwidth
     The distance between the two columns, the width of a rule between the columns, and the width of the columns, when the document class option twocolumn is in effect (see Document class options). See \twocolumn.

\headheight
     Height of the box that contains the running head.  The default in the article, report, and book classes is 12pt, at all type sizes.

\headsep
     Vertical distance between the bottom of the header line and the top of the main text.  The default in the article and report classes is 25pt.  In the book class the default is: if the document is set at 10pt then it is 0.25in, and at 11pt and 12pt it is 0.275in.

\footskip
     Distance from the baseline of the last line of text to the baseline of the page footer.  The default in the article and report classes is 30pt.  In the book class the default is: when the type size is 10pt the default is 0.35in, while at 11pt it is 0.38in, and at 12pt it is 30pt.

\linewidth
     Width of the current line, decreased for each nested list (see list).  That is, the nominal value for \linewidth is to equal \textwidth but for each nested list the \linewidth is decreased by the sum of that list's \leftmargin and \rightmargin (see itemize).

\marginparpush
\marginsep
\marginparwidth
     The minimum vertical space between two marginal notes, the horizontal space between the text body and the marginal notes, and the horizontal width of the notes.

     Normally marginal notes appear on the outside of the page, but the declaration \reversemarginpar changes that (and \normalmarginpar changes it back).

     The defaults for \marginparpush in both book and article classes are: 7pt if the document is set at 12pt, and 5pt if the document is set at 11pt or 10pt.

     For \marginsep, in article class the default is 10pt except if the document is set at 10pt and in two-column mode where the default is 11pt.

     For \marginsep in book class the default is 10pt in two-column mode and 7pt in one-column mode.

     For \marginparwidth in both book and article classes, in two-column mode the default is 60% of \paperwidth - \textwidth, while in one-column mode it is 50% of that distance.

\oddsidemargin
\evensidemargin
     The \oddsidemargin is the extra distance between the left side of the page and the text's left margin, on odd-numbered pages when the document class option twoside is chosen and on all pages when oneside is in effect.  When twoside is in effect, on even-numbered pages the extra distance on the left is evensidemargin.

     LaTeX's default is that \oddsidemargin is 40% of the difference between \paperwidth and \textwidth, and \evensidemargin is the remainder.

\paperheight
     The height of the paper, as distinct from the height of the print area. It is normally set with a document class option, as in \documentclass[a4paper]{article} (see Document class options).

\paperwidth
     The width of the paper, as distinct from the width of the print area. It is normally set with a document class option, as in \documentclass[a4paper]{article} (see Document class options).

\textheight
     The normal vertical height of the page body.  If the document is set at a nominal type size of 10pt then for an article or report the default is 43\baselineskip, while for a book it is 41\baselineskip.  At a type size of 11pt the default is 38\baselineskip for all document classes.  At 12pt it is 36\baselineskip for all classes.

\textwidth
     The full horizontal width of the entire page body.  For an article or report document, the default is 345pt when the chosen type size is 10pt, the default is 360pt at 11pt, and it is 390pt at 12pt.  For a book document, the default is 4.5in at a type size of 10pt, and 5in at 11pt or 12pt.

     In multi-column output, \textwidth remains the width of the entire page body, while \columnwidth is the width of one column (see \twocolumn).

     In lists (see list), \textwidth remains the width of the entire page body (and \columnwidth the width of the entire column), while \linewidth may decrease for nested lists.

     Inside a minipage (see minipage) or \parbox (see \parbox), all the width-related parameters are set to the specified width, and revert to their normal values at the end of the minipage or \parbox.

     This entry is included for completeness: \hsize is the TeX primitive parameter used when text is broken into lines.  It should not be used in normal LaTeX documents.

\topmargin
     Space between the top of the TeX page (one inch from the top of the paper, by default) and the top of the header.  The value is computed based on many other parameters: \paperheight - 2in - \headheight - \headsep - \textheight - \footskip, and then divided by two.

\topskip
     Minimum distance between the top of the page body and the baseline of the first line of text.  For the standard classes, the default is the same as the font size, e.g., 10pt at a type size of 10pt.

Floats
======

Some typographic elements, such as figures and tables, cannot be broken across pages.  They must be typeset outside of the normal flow of text, for instance floating to the top of a later page.

LaTeX can have a number of different classes of floating material. The default is the two classes, figure (see figure) and table (see table), but you can create a new class with the package float.

Within any one float class LaTeX always respects the order, so that the first figure in a document source must be typeset before the second figure.  However, LaTeX may mix the classes, so it can happen that while the first table appears in the source before the first figure, it appears in the output after it.

The placement of floats is subject to parameters, given below, that limit the number of floats that can appear at the top of a page, and the bottom, etc. If so many floats are queued that the limits prevent them all from fitting on a page then LaTeX places what it can and defers the rest to the next page.  In this way, floats may end up being typeset far from their place in the source.  In particular, a float that is big may migrate to the end of the document. In which event, because all floats in a class must appear in sequential order, every following float in that class also appears at the end.

In addition to changing the parameters, for each float you can tweak where the float placement algorithm tries to place it by using its PLACEMENT argument.  The possible values are a sequence of the letters below. The default for both figure and table, in both article and book classes, is tbp.

t
     (Top)---at the top of a text page.

b
     (Bottom)---at the bottom of a text page.  (However, b is not allowed for full-width floats (figure*) with double-column output.  To ameliorate this, use the stfloats or dblfloatfix package, but see the discussion at caveats in the FAQ: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=2colfloat.

h
     (Here)---at the position in the text where the figure environment appears.  However, h is not allowed by itself; t is automatically added.

     To absolutely force a float to appear ``here'', you can \usepackage{float} and use the H specifier which it defines.  For further discussion, see the FAQ entry at http://www.tex.ac.uk/cgi-bin/texfaq2html?label=figurehere.

p
     (Page of floats)---on a separate float page, which is a page containing no text, only floats.

!
     Used in addition to one of the above; for this float only, LaTeX ignores the restrictions on both the number of floats that can appear and the relative amounts of float and non-float text on the page. The ! specifier does not mean ``put the float here''; see above.

Note: the order in which letters appear in the PLACEMENT argument does not change the order in which LaTeX tries to place the float; for instance, btp has the same effect as tbp.  All that PLACEMENT does is that if a letter is not present then the algorithm does not try that location.  Thus, LaTeX's default of tbp is to try every location except placing the float where it occurs in the source.

To prevent LaTeX from moving floats to the end of the document or a chapter you can use a \clearpage command to start a new page and insert all pending floats. If a pagebreak is undesirable then you can use the afterpage package and issue \afterpage{\clearpage}.  This will wait until the current page is finished and then flush all outstanding floats.

LaTeX can typeset a float before where it appears in the source (although on the same output page) if there is a t specifier in the PLACEMENT parameter.  If this is not desired, and deleting the t is not acceptable as it keeps the float from being placed at the top of the next page, then you can prevent it by either using the flafter package or using the command \suppressfloats[t], which causes floats for the top position on this page to moved to the next page.

Parameters relating to fractions of pages occupied by float and non-float text (change them with \renewcommand{PARAMETER}{DECIMAL BETWEEN 0 AND 1}):

\bottomfraction
     The maximum fraction of the page allowed to be occupied by floats at the bottom; default .3.

\floatpagefraction
     The minimum fraction of a float page that must be occupied by floats; default .5.

\textfraction
     Minimum fraction of a page that must be text; if floats take up too much space to preserve this much text, floats will be moved to a different page.  The default is .2.

\topfraction
     Maximum fraction at the top of a page that may be occupied before floats; default .7.

Parameters relating to vertical space around floats (change them with \setlength{PARAMETER}{LENGTH EXPRESSION}):

\floatsep
     Space between floats at the top or bottom of a page; default 12pt plus2pt minus2pt.

\intextsep
     Space above and below a float in the middle of the main text; default 12pt plus2pt minus2pt for 10 point and 11 point documents, and 14pt plus4pt minus4pt for 12 point documents.

\textfloatsep
     Space between the last (first) float at the top (bottom) of a page; default 20pt plus2pt minus4pt.

Counters relating to the number of floats on a page (change them with \setcounter{CTRNAME}{NATURAL NUMBER}):

bottomnumber
     Maximum number of floats that can appear at the bottom of a text page; default 1.

dbltopnumber
     Maximum number of full-sized floats that can appear at the top of a two-column page; default 2.

topnumber
     Maximum number of floats that can appear at the top of a text page; default 2.

totalnumber
     Maximum number of floats that can appear on a text page; default 3.

The principal TeX FAQ entry relating to floats http://www.tex.ac.uk/cgi-bin/texfaq2html?label=floats contains suggestions for relaxing LaTeX's default parameters to reduce the problem of floats being pushed to the end.  A full explanation of the float placement algorithm is in Frank Mittelbach's article ``How to influence the position of float environments like figure and table in LaTeX?'' (http://latex-project.org/papers/tb111mitt-float.pdf).

Sectioning
**********

Sectioning commands provide the means to structure your text into units:

\part

\chapter
     (report and book class only)

\section

\subsection

\subsubsection

\paragraph

\subparagraph

All sectioning commands take the same general form, e.g.,

     \chapter[TOCTITLE]{TITLE}

In addition to providing the heading TITLE in the main text, the section title can appear in two other places:

 1. The table of contents.

 2. The running head at the top of the page.

You may not want the same text in these places as in the main text. To handle this, the sectioning commands have an optional argument TOCTITLE that, when given, specifies the text for these other places.

Also, all sectioning commands have *-forms that print TITLE as usual, but do not include a number and do not make an entry in the table of contents.  For instance:

     \section*{Preamble}

The \appendix command changes the way following sectional units are numbered.  The \appendix command itself generates no text and does not affect the numbering of parts.  The normal use of this command is something like

     \chapter{A Chapter}
     ...
     \appendix
     \chapter{The First Appendix}

The secnumdepth counter controls printing of section numbers. The setting

     \setcounter{secnumdepth}{LEVEL}

suppresses heading numbers at any depth > LEVEL, where chapter is level zero.  The default secnumdepth is 3 in LaTeX's article class and 2 in the book and report classes.  (see \setcounter.)

\@startsection
==============

Synopsis:

     \@startsection{NAME}{LEVEL}{INDENT}{BEFORESKIP}{AFTERSKIP}{STYLE}

Used to help redefine the behavior of commands that start sectioning divisions such as \section or \subsection.

Note that the titlesec package makes manipulation of sectioning easier.  Further, while most requirements for sectioning commands can be satisfied with \@startsection, some cannot.  For instance, in the standard LaTeX book and report classes the commands \chapter and \report are not constructed in this way.  To make such a command you may want to use the \secdef command.

Technically, \@startsection has the form

     \@startsection{NAME}{LEVEL}{INDENT}{BEFORESKIP}{AFTERSKIP}{STYLE}*[TOCTITLE]{TITLE}

(the star * is optional), so that issuing

     \renewcommand{\section}{\@startsection{NAME}{LEVEL}{INDENT}{BEFORESKIP}{AFTERSKIP}{STYLE}}

redefines \section to have the form \section*[TOCTITLE]{TITLE} (here too, the star * is optional).  See Sectioning.  This implies that when you write a command like \renewcommand{section}{...}, the \@startsection{...} must come last in the definition.  See the examples below.

name
      Name of the counter used to number the sectioning header.  This counter must be defined separately.  Most commonly this is either section, subsection, or paragraph.  Although in those three cases the counter name is the same as the sectioning command itself, using the same name is not required.

     Then \theNAME displays the title number and \NAMEmark is for the page headers.  See the third example below.

level
      An integer giving the depth of the sectioning command: 0 for chapter (only applies to the standard book and report classes), 1 for section, 2 for subsection, 3 for subsubsection, 4 for paragraph, and 5 for subparagraph.  In the book and report classes part has level -1, while in the article class part has level 0.

     If LEVEL is less than or equal to the value of secnumdepth then the titles for this sectioning command will be numbered.  For instance, in an article, if secnumdepth is 1 then a \section{Introduction} command will produce output like ``1 Introduction'' while \subsection{Discussion} will produce output like ``Discussion'', without the number prefix. See Sectioning/secnumdepth.

     If LEVEL is less than or equal to the value of TOCDEPTH then the table of contents will have an entry for this sectioning unit. For instance, in an article, if TOCDEPTH is 1 then the table of contents will list sections but not subsections.

indent
      A length giving the indentation of all of the title lines with respect to the left margin.  To have the title flush with the margin use 0pt.  A negative indentation such as -\parindent will move the title into the left margin.

beforeskip
      The absolute value of this length is the amount of vertical space that is inserted before this sectioning unit's title.  This space will be discarded if the sectioning unit happens to start at the top of a fresh page.  If this number is negative then the first paragraph following the header is not indented, if it is non-negative then the first paragraph is indented.  (Note that the negative of 1pt plus 2pt minus 3pt is -1pt plus -2pt minus -3pt.)

     For example, if BEFORESKIP is -3.5ex plus -1ex minus -0.2ex then to start the new sectioning unit, LaTeX will add about 3.5 times the height of a letter x in vertical space, and the first paragraph in the section will not be indented.  Using a rubber length, with plus and minus, is good practice here since it gives LaTeX more flexibility in making up the page (see Lengths).

     The full accounting of the vertical space between the baseline of the line prior to this sectioning unit's header and the baseline of the header is that it is the sum of the \parskip of the text font, the \baselineskip of the title font, and the absolute value of the BEFORESKIP.  This space is typically rubber so it may stretch or shrink.  (If the sectioning unit starts on a fresh page so that the vertical space is discarded then the baseline of the header text will be where LaTeX would put the baseline of the first text line on that page.)

afterskip
      This is a length.  If AFTERSKIP is non-negative then this is the vertical space inserted after the sectioning unit's title header.  If it is negative then the title header becomes a run-in header, so that it becomes part of the next paragraph. In this case the absolute value of the length gives the horizontal space between the end of the title and the beginning of the following paragraph.  (Note that the negative of 1pt plus 2pt minus 3pt is -1pt plus -2pt minus -3pt.)

     As with BEFORESKIP, using a rubber length, with plus and minus components, is good practice here since it gives LaTeX more flexibility in putting together the page.

     If afterskip is non-negative then the full accounting of the vertical space between the baseline of the sectioning unit's header and the baseline of the first line of the following paragraph is that it is the sum of the \parskip of the title font, the \baselineskip of the text font, and the value of AFTER. That space is typically rubber so it may stretch or shrink.  (Note that because the sign of afterskip changes the sectioning unit header's from standalone to run-in, you cannot use a negative afterskip to cancel part of the \parskip.)

style
      Controls the styling of the title.  See the examples below.  Typical commands to use here are \centering, \raggedright, \normalfont, \hrule, or \newpage.  The last command in STYLE may be one such as \MakeUppercase or \fbox that takes one argument. The section title will be supplied as the argument to this command. For instance, setting STYLE to \bfseries\MakeUppercase would produce titles that are bold and upper case.

These are LaTeX's defaults for the first three sectioning units that are defined with \@startsection, for the article, book, and report classes.

  section    subsection    subsubsection
NAME
section            subsection            subsubsection
LEVEL
1            2            3
INDENT
0pt            0pt            0pt
BEFORESKIP
-3.5ex plus -1ex minus -0.2ex
-3.25ex plus -1ex minus -0.2ex
-3.25ex plus -1ex minus -0.2ex
AFTERSKIP
2.3ex plus 0.2ex
1.5ex plus 0.2ex
1.5ex plus 0.2ex
STYLE
\normalfont\Large\bfseries
\normalfont\large\bfseries
\normalfont\normalsize\bfseries

Here are examples.  They go either in a package or class file or in the preamble of a LaTeX document.  If you put them in the preamble they must go between a \makeatletter command and a \makeatother.  (Probably the error message You can't use `\spacefactor' in vertical mode.  means that you forgot this.) See \makeatletter and \makeatother.

This will put section titles in large boldface type, centered.  It says \renewcommand because LaTeX's standard classes have already defined a \section.  For the same reason it does not define a section counter, or the commands \thesection and \l@section.

     \renewcommand\section{%
       \@startsection{section}% NAME
         {1}% LEVEL
         {0pt}% INDENT
         {-3.5ex plus -1ex minus -.2ex}% BEFORESKIP
         {2.3ex plus.2ex}% AFTERSKIP
         {\centering\normalfont\Large\bfseries}% STYLE
       }

This will put subsection titles in small caps type, inline with the paragraph.

     \renewcommand\subsection{%
       \@startsection{subsection}%  NAME
         {2}% LEVEL
         {0em}% INDENT
         {-1ex plus 0.1ex minus -0.05ex}% BEFORESKIP
         {-1em plus 0.2em}% AFTERSKIP
         {\scshape}% STYLE
       }

The prior examples redefined existing sectional unit title commands.  This defines a new one, illustrating the needed counter and macros to display that counter.

     \setcounter{secnumdepth}{6}% show counters this far down
     \newcounter{subsubparagraph}[subparagraph]% counter for numbering
     \renewcommand{\thesubsubparagraph}%               how to display
       {\thesubparagraph.\@arabic\c@subsubparagraph}%  numbering
     \newcommand{\subsubparagraph}{\@startsection
                              {subsubparagraph}%
                              {6}%
                              {0em}%
                              {\baselineskip}%
                              {0.5\baselineskip}%
                              {\normalfont\normalsize}}
     \newcommand*\l@subsubparagraph{\@dottedtocline{6}{10em}{5em}}% for toc
     \newcommand{\subsubparagraphmark}[1]{}% for page headers

Cross references
****************

One reason for numbering things such as figures and equations is to refer the reader to them, as in ``See Figure~3 for more details.''

Including the figure number in the source is poor practice since if that number changes as the document evolves then you must remember to update this reference by hand.  Instead, LaTeX has you write a label like \label{eq:GreensThm} and refer to it with See equation~\ref{eq:GreensThm}.

LaTeX writes the information from the labels to a file with the same name as the file containing the \label{...} but with an .aux extension.  (The information has the format \newlabel{LABEL}{{CURRENTLABEL}{PAGENUMBER}} where CURRENTLABEL is the current value of the macro \@currentlabel that is usually updated whenever you call \refstepcounter{COUNTER}.)

The most common side effect of the prior paragraph happens when your document has a forward reference, a \ref{KEY} that appears earlier than the associated \label{KEY}; see the example in the \pageref{...} description.  LaTeX gets the information for references from the .aux file.  If this is the first time you are compiling the document then you will get a message LaTeX Warning: Label(s) may have changed. Rerun to get cross references right. and in the output the reference will appear as two question marks ??, in boldface.  Or, if you change some things so the references change then you get the same warning and the output contains the old reference information.  The solution in either case is just to compile the document a second time.

\label
======

Synopsis:

     \label{KEY}

Assign a reference number to KEY.  In ordinary text \label{KEY} assigns to KEY the number of the current sectional unit. Inside an environment with numbering, such as a table or theorem environment, \label{KEY} assigns to KEY the number of that environment.  Retrieve the assigned number with the \ref{KEY} command (see \ref).

A key name can consist of any sequence of letters, digits, or common punctuation characters.  Upper and lowercase letters are distinguished, as usual.

A common convention is to use labels consisting of a prefix and a suffix separated by a colon or period.  This helps to avoid accidentally creating two labels with the same name, and makes your source more readable.  Some commonly-used prefixes:

ch
     for chapters

sec
     for lower-level sectioning commands

fig
     for figures

tab
     for tables

eq
     for equations

Thus, \label{fig:Euler} is a label for a figure with a portrait of the great man.

In this example below the key sec:test will get the number of the current section and the key fig:test will get the number of the figure.  (Incidentally, put labels after captions in figures and tables.)

     \section{section name}
     \label{sec:test}
     This is Section~\ref{sec:test}.
     \begin{figure}
       ...
       \caption{caption text}
       \label{fig:test}
     \end{figure}
     See Figure~\ref{fig:test}.

\pageref{KEY}
=============

Synopsis:

     \pageref{KEY}

Produce the page number of the place in the text where the corresponding \label{KEY} command appears.

In this example the \label{eq:main} is used both for the formula number and for the page number.  (Note that the two references are forward references, so this document would need to be compiled twice to resolve those.)

     The main result is formula~\ref{eq:main} on page~\pageref{eq:main}.
       ...
     \begin{equation} \label{eq:main}
        \mathbf{P}=\mathbf{NP}
     \end{equation}

\ref{KEY}
=========

Synopsis:

     \ref{KEY}

Produces the number of the sectional unit, equation, footnote, figure, ..., of the corresponding \label command (see \label).  It does not produce any text, such as the word `Section' or `Figure', just the bare number itself.

In this example, the \ref{popular} produces 2.  Note that it is a forward reference since it comes before \label{popular}.

     The most widely-used format is item number~\ref{popular}.
     \begin{enumerate}
     \item Plain \TeX
     \item \label{popular} \LaTeX
     \item Con\TeX t
     \end{enumerate}

Environments
************

LaTeX provides many environments for delimiting certain behavior. An environment begins with \begin and ends with \end, like this:

     \begin{ENVIRONMENT-NAME}
       ...
     \end{ENVIRONMENT-NAME}

The ENVIRONMENT-NAME at the beginning must exactly match that at the end. For instance, the input \begin{table*}...\end{table} will cause an error like: ! LaTeX Error: \begin{table*} on input line 5 ended by \end{table}.

Environments are executed within a group.

abstract
========

Synopsis:

     \begin{abstract}
     ...
     \end{abstract}

Produce an abstract, possibly of multiple paragraphs.  This environment is only defined in the article and report document classes (see Document classes).

Using the example below in the article class produces a displayed paragraph.  Document class option titlepage causes the abstract to be on a separate page (see Document class options); this is the default only in the report class.

     \begin{abstract}
       We compare all known accounts of the proposal made by Porter Alexander
       to Robert E Lee at the Appomattox Court House that the army continue
       in a guerrilla war, which Lee refused.
     \end{abstract}

The next example produces a one column abstract in a two column document (for a more flexible solution, use the package abstract).

     \documentclass[twocolumn]{article}
       ...
     \begin{document}
     \title{Babe Ruth as Cultural Progenitor: a Atavistic Approach}
     \author{Smith \\ Jones \\ Robinson\thanks{Railroad tracking grant.}}
     \twocolumn[
       \begin{@twocolumnfalse}
          \maketitle
          \begin{abstract}
            Ruth was not just the Sultan of Swat, he was the entire swat
            team.
          \end{abstract}
        \end{@twocolumnfalse}
        ]
     {   % by-hand insert a footnote at page bottom
      \renewcommand{\thefootnote}{\fnsymbol{footnote}}
      \footnotetext[1]{Thanks for all the fish.}
     }

array
=====

Synopsis:

     \begin{array}{COLS}
       COLUMN 1 ENTRY &COLUMN 2 ENTRY ... &COLUMN N ENTRY \\
       ...
     \end{array}

or

     \begin{array}[POS]{COLS}
       COLUMN 1 ENTRY &COLUMN 2 ENTRY ... &COLUMN N ENTRY \\
       ...
     \end{array}

Produce a mathematical array.  This environment can only be used in math mode, and normally appears within a displayed mathematics environment such as equation (see equation).  Column entries are separated by an ampersand (&).  Rows are terminated with double-backslashes (see \\).

The required argument COLS describes the number of columns, their alignment, and the formatting of the intercolumn regions.  See tabular for the complete description of COLS, and of the other common features of the two environments, including the optional POS argument.

There are two ways that array diverges from tabular.  The first is that array entries are typeset in math mode, in textstyle (except if the COLS definition specifies the column with p{...}, which causes the entry to be typeset in text mode). The second is that, instead of tabular's parameter \tabcolsep, LaTeX's intercolumn space in an array is governed by \arraycolsep, which gives half the width between columns. The default for this is 5pt.

To obtain arrays with braces the standard is to use the amsmath package.  It comes with environments pmatrix for an array surrounded by parentheses (...), bmatrix for an array surrounded by square brackets [...], Bmatrix for an array surrounded by curly braces {...}, vmatrix for an array surrounded by vertical bars |...|, and Vmatrix for an array surrounded by double vertical bars ||...||, along with a number of other array constructs.

Here is an example of an array:

     \begin{equation}
       \begin{array}{cr}
         \sqrt{y}  &12.3 \\
         x^2       &3.4
       \end{array}
     \end{equation}

The next example works if \usepackage{amsmath} is in the preamble:

     \begin{equation}
       \begin{vmatrix}{cc}
         a  &b \\
         c  &d
       \end{vmatrix}=ad-bc
     \end{equation}

center
======

Synopsis:

     \begin{center}
       ... text ...
     \end{center}

Create a new paragraph consisting of a sequence of lines that are centered within the left and right margins on the current page.  Use double-backslash to get a line break at a particular spot (see \\). If some text environment body is too long to fit on a line, LaTeX will insert line breaks that avoid hyphenation and avoid stretching or shrinking any interword space.

This environment inserts space above and below the text body.  See \centering to avoid such space, for example inside a figure environment.

This example produces three centered lines.  There is extra vertical space between the last two lines.

     \begin{center}
       A Thesis Submitted in Partial Fufillment \\
       of the Requirements of \\[0.5ex]
       the School of Environmental Engineering
     \end{center}

In this example, depending on the page's line width, LaTeX may choose a line break for the part before the double backslash.  If so, it will center each of the two lines and if not it will center the single line. Then LaTeX will break at the double backslash, and will center the ending.

     \begin{center}
       My father considered that anyone who went to chapel and didn't drink
       alcohol was not to be tolerated.\\
       I grew up in that belief.  --Richard Burton
     \end{center}

A double backslash after the final line is optional.

\centering
----------

A declaration that causes material in its scope to be centered.  It is most often used inside an environment such as figure, or in a parbox.

Unlike the center environment, the \centering command does not add vertical space above and below the text.

It also does not start a new paragraph; it simply changes how LaTeX formats paragraph units.  If ww {\centering xx \\ yy} zz is surrounded by blank lines then LaTeX will create a paragraph whose first line ww xx is centered and whose second line, not centered, contains yy zz.  Usually what is desired is for the scope of the declaration to contain a blank line or the \end command of an environment such as figure or table that ends the paragraph unit.  Thus, if {\centering xx \\ yy\par} zz is surrounded by blank lines then it makes a new paragraph with two centered lines xx and yy, followed by a new paragraph with zz that is formatted as usual.  See also the following example.

This example's \centering causes the graphic to be horizontally centered.

     \begin{figure}
       \centering
       \includegraphics[width=0.6\textwidth]{ctan_lion.png}
       \caption{CTAN Lion}  \label{fig:CTANLion}
     \end{figure}

The scope of the \centering ends with the \end{figure}.

description
===========

Synopsis:

     \begin{description}
     \item[LABEL OF FIRST ITEM] text of first item
     \item[LABEL OF SECOND ITEM] text of second item
       ...
     \end{description}

Environment to make a labeled list of items.  Each item's LABEL is typeset in bold, and is flush left so that long labels continue into the first line of the item text.  There must be at least one item; having none causes the LaTeX error Something's wrong--perhaps a missing \item.

This example shows the environment used for a sequence of definitions. The labels lama and llama come out in boldface with their left edges aligned on the left margin.

     \begin{definition}
       \item[lama] A priest.
       \item[llama] A beast.
     \end{definition}

Start list items with the \item command (see \item).  Use the optional labels, as in \item[Main point], because there is no sensible default.  Following the \item is optional text, which may contain multiple paragraphs.

Since the labels are in bold style, if the label text calls for a font change given in argument style (see Font styles) then it will come out bold.  For instance, if the label text calls for typewriter with \item[\texttt{label text}] then it will appear in bold typewriter, if that is available. The simplest way to get non-bold typewriter is to use declarative style: \item[{\tt label text}].  Similarly, get the standard roman font with \item[{\rm label text}].

For other major LaTeX labelled list environments, see itemize and enumerate.  Unlike those environments, nesting description environments does not change the default label; it is boldface and flush left at all levels.

For information about list layout parameters, including the default values, and for information about customizing list layout, see list.  The package enumitem is useful for customizing lists.

This example changes the description labels to small caps.

     \renewcommand{\descriptionlabel}[1]{%
       {\hspace{\labelsep}\textsc{#1}}}

displaymath
===========

Synopsis:

     \begin{displaymath}
     MATH TEXT
     \end{displaymath}

Environment to typeset the math text on its own line, in display style and centered.  To make the text be flush-left use the global option fleqn; see Document class options.

In the displaymath environment no equation number is added to the math text. One way to get an equation number is to use the equation environment (see equation).

LaTeX will not break the MATH TEXT across lines.

Note that the amsmath package has significantly more extensive displayed equation facilities.  For example, there are a number of ways in that package for having math text broken across lines.

The construct \[MATH TEXT\] is essentially a synonym for \begin{displaymath}MATH TEXT\end{displaymath} but the latter is easier to work with in the source file; for instance, searching for a square bracket may get false positives but the word displaymath will likely be unique.  (The construct $$MATH TEXT$$ from Plain TeX is sometimes mistakenly used as a synonym for displaymath.  It is not a synonym, because the displaymath environment checks that it isn't started in math mode and that it ends in math mode begun by the matching environment start, because the displaymath environment has different vertical spacing, and because the displaymath environment honors the fleqn option.)

The output from this example is centered and alone on its line.

     \begin{displaymath}
       \int_1^2 x^2\,dx=7/3
     \end{displaymath}

Also, the integral sign is larger than the inline version \( \int_1^2 x^2\,dx=7/3 \) produces.

document
========

The document environment encloses the entire body of a document. It is required in every LaTeX document.  See Starting and ending.

\AtBeginDocument
----------------

Synopsis:

     \AtBeginDocument{CODE}

Save CODE and execute it when \begin{document} is executed, at the very end of the preamble.  The code is executed after the font selection tables have been set up, so the normal font for the document is the current font.  However, the code is executed as part of the preamble so you cannot do any typesetting with it.

You can issue this command more than once; the successive code lines will be executed in the order that you gave them.

\AtEndDocument
--------------

Synopsis:

     \AtEndDocument{CODE}

Save CODE and execute it near the end of the document. Specifically, it is executed when \end{document} is executed, before the final page is finished and before any leftover floating environments are processed. If you want some of the code to be executed after these two processes then include a \clearpage at the appropriate point in CODE.

You can issue this command more than once; the successive code lines will be executed in the order that you gave them.

enumerate
=========

Synopsis:

     \begin{enumerate}
     \item[OPTIONAL LABEL OF FIRST ITEM] text of first item
     \item[OPTIONAL LABEL OF SECOND ITEM] text of second item
     ...
     \end{enumerate}

Environment to produce a numbered list of items.  The format of the label numbering depends on the nesting level of this environment; see below. The default top-level numbering is 1., 2., etc. Each enumerate list environment must have at least one item; having none causes the LaTeX error Something's wrong--perhaps a missing \item.

This example gives the first two finishers in the 1908 Olympic marathon. As a top-level list the labels would come out as 1. and 2..

     \begin{enumerate}
      \item Johnny Hayes (USA)
      \item Charles Hefferon (RSA)
     \end{enumerate}

Start list items with the \item command (see \item).  If you give \item an optional argument by following it with square brackets, as in \item[Interstitial label], then the next item will continue the interrupted sequence (see \item).  That is, you will get labels like 1., then Interstitial label, then 2..  Following the \item is optional text, which may contain multiple paragraphs.

Enumerations may be nested within other enumerate environments, or within any paragraph-making environment such as itemize (see itemize), up to four levels deep.  This gives LaTeX's default for the format at each nesting level, where 1 is the top level, the outermost level.

 1. arabic number followed by a period: 1., 2., ...

 2. lower case letter inside parentheses: (a), (b) ...

 3. lower case roman numeral followed by a period: i., ii., ...

 4. upper case letter followed by a period: A., B., ...

The enumerate environment uses the counters \enumi through \enumiv (see Counters).

For other major LaTeX labeled list environments, see description and itemize.  For information about list layout parameters, including the default values, and for information about customizing list layout, see list.  The package enumitem is useful for customizing lists.

To change the format of the label use \renewcommand (see \newcommand & \renewcommand) on the commands \labelenumi through \labelenumiv. For instance, this first level list will be labelled with uppercase letters, in boldface, and without a trailing period.

     \renewcommand{\labelenumi}{\textbf{\Alph{enumi}}}
     \begin{enumerate}
       \item Shows as boldface A
       \item Shows as boldface B
     \end{enumerate}

For a list of counter-labeling commands see \alph \Alph \arabic \roman \Roman \fnsymbol.

eqnarray
========

First, a caveat: the eqnarray environment is depreciated.  It has infelicities that cannot be overcome, including spacing that is inconsistent with other mathematics elements (see the article ``Avoid eqnarray!'' by Lars Madsen http://tug.org/TUGboat/tb33-1/tb103madsen.pdf).  New documents should include the amsmath package and use the displayed mathematics environments provided there, such as the align environment.

Nevertheless, for completeness and for a reference when working with old documents, a synopsis:

     \begin{eqnarray}
       FIRST FORMULA LEFT  &FIRST FORMULA MIDDLE  &FIRST FORMULA RIGHT \\
       ...
     \end{eqnarray}

or

     \begin{eqnarray*}
       FIRST FORMULA LEFT  &FIRST FORMULA MIDDLE  &FIRST FORMULA RIGHT \\
       ...
     \end{eqnarray*}

Display a sequence of equations or inequalities.  The left and right sides are typeset in display mode, while the middle is typeset in text mode.

It is similar to a three-column array environment, with items within a row separated by an ampersand (&), and with rows separated by double backslash  \\). The starred form of line break (\\*) can also be used to separate equations, and will disallow a page break there (see \\).

The unstarred form eqnarray places an equation number on every line (using the equation counter), unless that line contains a \nonumber command.  The starred form eqnarray* omits equation numbering, while otherwise being the same.

The command \lefteqn is used for splitting long formulas across lines. It typesets its argument in display style flush left in a box of zero width.

This example shows three lines.  The first two lines make an inequality, while the third line has not entry on the left side.

     \begin{eqnarray*}
       \lefteqn{x_1+x_2+\cdots+x_n}     \\
         &\leq &y_1+y_2+\cdots+y_n      \\
         &=    &z+y_3+\cdots+y_n
     \end{eqnarray*}

equation
========

Synopsis:

     \begin{equation}
       math text
     \end{equation}

Make a displaymath environment (see displaymath) with an equation number in the right margin.

The equation number is generated using the equation counter.

You should have no blank lines between \begin{equation} and \begin{equation}, or LaTeX will tell you that there is a missing dollar sign, $$.

Note that the amsmath package has extensive displayed equation facilities.  Those facilities are the best approach for such output in new documents.

figure
======

Synopsis:

     \begin{figure}[PLACEMENT]
       figure body
     \caption[LOFTITLE]{TITLE}
     \label{LABEL}
     \end{figure}

or

     \begin{figure*}[PLACEMENT]
       figure body
     \caption[LOFTITLE]{TITLE}
     \label{LABEL}
     \end{figure*}

A class of floats (see Floats).  Because they cannot be split across pages, they are not typeset in sequence with the normal text but instead are ``floated'' to a convenient place, such as the top of a following page.

For the possible values of PLACEMENT and their effect on the float placement algorithm, see Floats.

The starred form figure* is used when a document is in double-column mode (see \twocolumn).  It produces a figure that spans both columns, at the top of the page.  To add the possibility of placing at a page bottom see the discussion of PLACEMENT b in Floats.

The figure body is typeset in a parbox of width \textwidth and so it can contain text, commands, etc.

The label is optional; it is used for cross references (see Cross references). The optional \caption command specifies caption text for the figure.  By default it is numbered.  If LOFTITLE is present, it is used in the list of figures instead of TITLE (see Tables of contents).

This example makes a figure out of a graphic.  It requires one of the packages graphics or graphicx.  The graphic, with its caption, will be placed at the top of a page or, if it is pushed to the end of the document, on a page of floats.

     \begin{figure}[t]
       \centering
       \includegraphics[width=0.5\textwidth]{CTANlion.png}
       \caption{The CTAN lion, by Duane Bibby}
     \end{figure}

filecontents: Write an external file
====================================

Synopsis:

     \begin{filecontents}{FILENAME}
       TEXT
     \end{filecontents}

or

     \begin{filecontents*}{FILENAME}
       TEXT
     \end{filecontents*}

Create a file named FILENAME and fill it with TEXT.  The unstarred version of the environment filecontents prefixes the content of the created file with a header; see the example below.  The starred version filecontents* does not include the header.

This environment can be used anywhere in the preamble, although it often appears before the \documentclass command.  It is typically used when a source file requires a nonstandard style or class file.  The environment will write that file to the directory containing the source and thus make the source file self-contained.  Another use is to include bib references in the file, again to make it self-contained.

The environment checks whether a file of that name already exists and if so, does not do anything.  There is a filecontents package that redefines the filecontents environment so that instead of doing nothing in that case, it will overwrite the existing file.

For example, this document

     \documentclass{article}
     \begin{filecontents}{JH.sty}
     \newcommand{\myname}{Jim Hef{}feron}
     \end{filecontents}
     \usepackage{JH}
     \begin{document}
     Article by \myname.
     \end{document}

produces this file JH.sty.

     %% LaTeX2e file `JH.sty'
     %% generated by the `filecontents' environment
     %% from source `test' on 2015/10/12.
     %%
     \newcommand{\myname}{Jim Hef{}feron}

flushleft
=========

     \begin{flushleft}
     LINE1 \\
     LINE2 \\
     ...
     \end{flushleft}

The flushleft environment allows you to create a paragraph consisting of lines that are flush to the left-hand margin and ragged right. Each line must be terminated with the string \\.

\raggedright
------------

The \raggedright declaration corresponds to the flushleft environment.  This declaration can be used inside an environment such as quote or in a parbox.

Unlike the flushleft environment, the \raggedright command does not start a new paragraph; it only changes how LaTeX formats paragraph units.  To affect a paragraph unit's format, the scope of the declaration must contain the blank line or \end command that ends the paragraph unit.

flushright
==========

     \begin{flushright}
     LINE1 \\
     LINE2 \\
     ...
     \end{flushright}

The flushright environment allows you to create a paragraph consisting of lines that are flush to the right-hand margin and ragged left.  Each line must be terminated with the control sequence \\.

\raggedleft
-----------

The \raggedleft declaration corresponds to the flushright environment.  This declaration can be used inside an environment such as quote or in a parbox.

Unlike the flushright environment, the \raggedleft command does not start a new paragraph; it only changes how LaTeX formats paragraph units.  To affect a paragraph unit's format, the scope of the declaration must contain the blank line or \end command that ends the paragraph unit.

itemize
=======

Synopsis:

     \begin{itemize}
     \item[OPTIONAL LABEL OF FIRST ITEM] text of first item
     \item[OPTIONAL LABEL OF SECOND ITEM] text of second item
     ...
     \end{itemize}

The itemize environment produces an ``unordered'', ``bulleted'' list.  The format of the label numbering depends on the nesting level of this environment; see below.  Each itemize list environment must have at least one item; having none causes the LaTeX error Something's wrong--perhaps a missing \item.

This example gives a two-item list.  As a top-level list each label would come out as a bullet, *.

     \begin{itemize}
      \item Pencil and watercolor sketch by Cassandra
      \item Rice portrait
     \end{itemize}

Start list items with the \item command (see \item).  If you give \item an optional argument by following it with square brackets, as in \item[Optional label], then by default it will appear in bold and be flush right, so it could extend into the left margin.  For labels that are flush left see the description environment. Following the \item is optional text, which may contain multiple paragraphs.

Itemized lists can be nested within one another, up to four levels deep. They can also be nested within other paragraph-making environments, such as enumerate (see enumerate).  The itemize environment uses the commands \labelitemi through \labelitemiv to produce the default label (this also uses the convention of lower case roman numerals at the end of the command names that signify the nesting level).  These are the default marks at each level.

 1. * (bullet, from \textbullet)

 2. -- (bold en-dash, from \normalfont\bfseries\textendash)

 3. * (asterisk, from \textasteriskcentered)

 4. . (centered dot, rendered here as a period, from \textperiodcentered)

Change the labels with \renewcommand.  For instance, this makes the first level use diamonds.

     \renewcommand{\labelitemi}{$\diamond$}

The distance between the left margin of the enclosing environment and the left margin of the itemize list is determined by the parameters \leftmargini through \leftmarginvi.  (Note the convention of using lower case roman numerals a the end of the command name to denote the nesting level.)  The defaults are: 2.5em in level 1 (2em in two-column mode), 2.2em in level 2, 1.87em in level 3, and 1.7em in level 4, with smaller values for more deeply nested levels.

For other major LaTeX labeled list environments, see description and enumerate.  For information about list layout parameters, including the default values, and for information about customizing list layout, see list.  The package enumitem is useful for customizing lists.

This example greatly reduces the margin space for outermost itemized lists.

     \setlength{\leftmargini}{1.25em} % default 2.5em

Especially for lists with short items, it may be desirable to elide space between items.  Here is an example defining an itemize* environment with no extra spacing between items, or between paragraphs within a single item (\parskip is not list-specific, see \parskip):

     \newenvironment{itemize*}%
       {\begin{itemize}%
         \setlength{\itemsep}{0pt}%
         \setlength{\parsep}{0pt}}%
         \setlength{\parskip}{0pt}}%
       {\end{itemize}}

letter environment: writing letters
===================================

This environment is used for creating letters.  See Letters.

list
====

Synopsis:

     \begin{list}{LABELING}{SPACING}
     \item[OPTIONAL LABEL OF FIRST ITEM] text of first item
     \item[OPTIONAL LABEL OF SECOND ITEM] text of second item
     ...
     \end{list}

The list environment is a generic environment for constructing more specialized lists.  It is most often used to create lists via the description, enumerate, and itemize environments (see description, enumerate, and itemize).

Also, many standard LaTeX environments that are not visually lists are constructed using list, including quotation, quote, center, verbatim, and plenty more (see quotation and quote, see center, see flushright).

The third-party package enumitem is useful for customizing lists. Here, we describe the list environment by defining a new custom environment.

     \newcounter{namedlistcounter}  % number the items
     \newenvironment{named}
       {\begin{list}
          {Item~\Roman{namedlistcounter}.} % labeling argument
          {\usecounter{namedlistcounter}   % spacing argument
           \setlength{\leftmargin}{3.5em}} % still spacing arg
       }
       {\end{list}}

     \begin{named}
       \item Shows as ``Item~I.''
       \item[Special label.] Shows as ``Special label.''
       \item Shows as ``Item~II.''
     \end{named}

The list environment's mandatory first argument, LABELING, specifies the default labeling of list items.  It can contain text and LaTeX commands, as above where it contains both Item and \Roman{...}.  LaTeX forms the label by putting the LABELING argument in a box of width \labelwidth.  If the label is wider than that, the additional material extends to the right.  When making an instance of a list you can override the default labeling by giving \item an optional argument by including square braces and the text, as in the above \item[Special label.]; see \item.

The label box is constructed by the command \makelabel.  By default it positions the contents flush right.  It takes one argument, the label.  It typesets the contents in LR mode. An example of changing its definition is that to the above example before the definition of the named environment add \newcommand{\namedmakelabel}[1]{\textsc{#1}}, and between the \setlength command and the parenthesis that closes the SPACING argument also add \let\makelabel\namedmakelabel. Then the items will be typeset in small caps.  Similarly, changing the second code line to \let\makelabel\fbox puts the labels inside a framed box.  Another example is at the bottom of this entry.

The mandatory second argument SPACING can have a list of commands to redefine the spacing parameters for the list, such as \setlength{\labelwidth}{2em}.  If this argument is empty, i.e., {}, then the list will have the default spacing given below.  To number the items using a counter, put \usecounter{COUNTERNAME} in this argument (see \usecounter).

Below are the spacing parameters for list formatting.  See also the figure below.  Each is a length (see Lengths).  The vertical spaces are normally rubber lengths, with plus and minus components, to give TeX flexibility in setting the page.  Change each with a command such as \setlength{itemsep}{2pt plus1pt minus1pt}.  For some effects these lengths should be zero or negative.  Default values for derived environments such as itemize can be changed from the values shown here for the basic list.

\itemindent
     Extra horizontal space indentation, beyond leftmargin, of the first line each item.  Its default value is 0pt.

\itemsep
     Vertical space between items, beyond the \parsep.  The defaults for the first three levels in LaTeX's article, book, and report classes at 10 point size are: 4pt plus2pt minus1pt, \parsep (that is, 2pt plus1pt minus1pt), and \topsep (that is, 2pt plus1pt minus1pt).  The defaults at 11 point are: 4.5pt plus2pt minus1pt, \parsep (that is, 2pt plus1pt minus1pt), and topsep (that is, 2pt plus1pt minus1pt).  The defaults at 12 point are: 5pt plus2.5pt minus1pt, \parsep (that is, 2.5pt plus1pt minus1pt), and \topsep (that is, 2.5pt plus1pt minus1pt).

\labelsep
     Horizontal space between the label and text of an item. The default for LaTeX's article, book, and report classes is 0.5em.

\labelwidth
     Horizontal width.  The box containing the label is nominally this wide. If \makelabel returns text that is wider than this then the first line of the item will be indented to make room for this extra material. If \makelabel returns text of width less than or equal to \labelwidth then LaTeX's default is that the label is typeset flush right in a box of this width.

     The left edge of the label box is \leftmargin+\itemindent-\labelsep-\labelwidth from the left margin of the enclosing environment.

     The default for LaTeX's article, book, and report classes at the top level is \leftmargini-\labelsep, (which is 2em in one column mode and 1.5em in two column mode).  At the second level it is \leftmarginii-\labelsep, and at the third level it is \leftmarginiii-\labelsep.  These definitions make the label's left edge coincide with the left margin of the enclosing environment.

\leftmargin
     Horizontal space between the left margin of the enclosing environment (or the left margin of the page if this is a top-level list), and the left margin of this list.  It must be non-negative.

     In the standard LaTeX document classes, a top-level list has this set to the value of \leftmargini, while a list that is nested inside a top-level list has this margin set to \leftmarginii.  More deeply nested lists get the values of \leftmarginiii through \leftmarginvi.  (Nesting greater than level five generates the error message Too deeply nested.)

     The defaults for the first three levels in LaTeX's article, book, and report classes are: \leftmargini is 2.5em (in two column mode, 2em), \leftmarginii is 2.2em, and \leftmarginiii is 1.87em.

\listparindent
     Horizontal space of additional line indentation, beyond \leftmargin, for second and subsequent paragraphs within a list item.  A negative value makes this an ``outdent''.  Its default value is 0pt.

\parsep
     Vertical space between paragraphs within an item.  In the book and article classes The defaults for the first three levels in LaTeX's article, book, and report classes at 10 point size are: 4pt plus2pt minus1pt, 2pt plus1pt minus1pt, and 0pt.  The defaults at 11 point size are: 4.5pt plus2pt minus1pt, 2pt plus1pt minus1pt, and 0pt.  The defaults at 12 point size are: 5pt plus2.5pt minus1pt, 2.5pt plus1pt minus1pt, and 0pt.

\partopsep
     Vertical space added, beyond \topsep+\parskip, to the top and bottom of the entire environment if the list instance is preceded by a blank line.  (A blank line in the LaTeX source before the list changes spacing at both the top and bottom of the list; whether the line following the list is blank does not matter.)

     The defaults for the first three levels in LaTeX's article, book, and report classes at 10 point size are: 2pt plus1 minus1pt, 2pt plus1pt minus1pt, and 1pt plus0pt minus1pt.  The defaults at 11 point are: 3pt plus1pt minus1pt, 3pt plus1pt minus1pt, and 1pt plus0pt minus1pt).  The defaults at 12 point are: 3pt plus2pt minus3pt, 3pt plus2pt minus2pt, and 1pt plus0pt minus1pt.

\rightmargin
     Horizontal space between the right margin of the list and the right margin of the enclosing environment.  Its default value is 0pt. It must be non-negative.

\topsep
     Vertical space added to both the top and bottom of the list, in addition to \parskip (see \parskip).  The defaults for the first three levels in LaTeX's article, book, and report classes at 10 point size are: 8pt plus2pt minus4pt, 4pt plus2pt minus1pt, and 2pt plus1pt minus1pt.  The defaults at 11 point are: 9pt plus3pt minus5pt, 4.5pt plus2pt minus1pt, and 2pt plus1pt minus1pt.  The defaults at 12 point are: 10pt plus4pt minus6pt, 5pt plus2.5pt minus1pt, and 2.5pt plus1pt minus1pt.

This shows the horizontal and vertical distances.

The lengths shown are listed below.  The key relationship is that the right edge of the bracket for H1 equals the right edge of the bracket for H4, so that the left edge of the label box is at H3+H4-(H0+H1).

v0
     \topsep + \parskip if the list environment does not start a new paragraph, and \topsep+\parskip+\partopsep if it does

v1
     \parsep

v2
     \itemsep+\parsep

v3
     Same as V0.  (This space is affected by whether a blank line appears in the source above the environment; whether a blank line appears in the source below the environment does not matter.)

h1
     \labelsep

h2
     \listparindent

h3
     \leftmargin

h4
     \itemindent

h5
     \rightmargin

The list's left and right margins, shown above as H3 and H5, are with respect to the ones provided by the surrounding environment, or with respect to the page margins for a top-level list.  The line width used for typesetting the list items is \linewidth (see Page layout parameters).  For instance, set the list's left margin to be one quarter of the distance between the left and right margins of the enclosing environment with \setlength{\leftmargin}{0.25\linewidth}.

Page breaking in a list structure is controlled by the three parameters below. For each, the LaTeX default is -\@lowpenalty, that is, -51.  Because it is negative, it somewhat encourages a page break at each spot.  Change it with, e.g., \@beginparpenalty=9999; a value of 10000 prohibits a page break.

\@beginparpenalty
     The page breaking penalty for breaking before the list (default -51).

\@itempenalty
     The page breaking penalty for breaking before a list item (default -51).

\@endparpenalty
     The page breaking penalty for breaking after a list (default -51).

This example has the labels in red.  They are numbered, and the left edge of the label lines up with the left edge of the item text.

     \usepackage{color}
     \newcounter{cnt}
     \newcommand{\makeredlabel}[1]{\textcolor{red}{#1.}}
     \newenvironment{redlabel}
       {\begin{list}
         {\arabic{cnt}}
         {\usecounter{cnt}
          \setlength{\labelwidth}{0em}
          \setlength{\labelsep}{0.5em}
          \setlength{\leftmargin}{1.5em}
          \setlength{\itemindent}{0.5em} % equals \labelwidth+\labelsep
          \let\makelabel=\makeredlabel
         }
       }
     {\end{list} }

\item: An entry in a list
-------------------------

Synopsis:

     \item text of item

or

     \item[OPTIONAL-LABEL] text of item

An entry in a list.  The entries are prefixed by a label, whose default depends on the list type.

Because the optional label is surrounded by square brackets [...], if you have an item whose text starts with [, you have to to hide the bracket inside curly braces, as in: \item {[} is an open square bracket; otherwise, LaTeX will think it marks the start of an optional label.

Similarly, if the item does have the optional label and you need a close square bracket inside that label, you must hide it in the same way: \item[Close square bracket, {]}].  See LaTeX command syntax.

In this example the enumerate list has two items that use the default label and one that uses the optional label.

     \begin{enumerate}
       \item Moe
       \item[sometimes] Shemp
       \item Larry
     \end{enumerate}

The first item is labelled 1., the second item is labelled sometimes, and the third item is labelled 2..  Because of the optional label in the second item, the third item is not labelled 3..

trivlist: A restricted form of list
-----------------------------------

Synopsis:

     \begin{trivlist}
       ...
     \end{trivlist}

A restricted version of the list environment, in which margins are not indented and an \item without an optional argument produces no text.  It is most often used in macros, to define an environment where the \item command as part of the environment's definition.  For instance, the center environment is defined essentially like this:

     \newenvironment{center}
       {\begin{trivlist}\centering\item\relax}
       {\end{trivlist}}

Using trivlist in this way allows the macro to inherit some common code: combining vertical space of two adjacent environments; detecting whether the text following the environment should be considered a new paragraph or a continuation of the previous one; adjusting the left and right margins for possible nested list environments.

Specifically, trivlist uses the current values of the list parameters (see list), except that \parsep is set to the value of \parskip, and \leftmargin, \labelwidth, and \itemindent are set to zero.

This example outputs the items as two paragraphs, except that (by default) they have no paragraph indent and are vertically separated.

     \begin{trivlist}
     \item The \textit{Surprise} is not old; no one would call her old.
     \item She has a bluff bow, lovely lines.
     \end{trivlist}

math
====

Synopsis:

     \begin{math}
     MATH
     \end{math}

The math environment inserts given MATH material within the running text.  \(...\) and $...$ are synonyms. See Math formulas.

minipage
========

     \begin{minipage}[POSITION][HEIGHT][INNER-POS]{WIDTH}
     TEXT
     \end{minipage}

The minipage environment typesets its body TEXT in a block that will not be broken across pages.  This is similar to the \parbox command (see \parbox), but unlike \parbox, other paragraph-making environments can be used inside a minipage.

The arguments are the same as for \parbox (see \parbox).

By default, paragraphs are not indented in the minipage environment.  You can restore indentation with a command such as \setlength{\parindent}{1pc} command.

Footnotes in a minipage environment are handled in a way that is particularly useful for putting footnotes in figures or tables.  A \footnote or \footnotetext command puts the footnote at the bottom of the minipage instead of at the bottom of the page, and it uses the \mpfootnote counter instead of the ordinary footnote counter (see Counters).

However, don't put one minipage inside another if you are using footnotes; they may wind up at the bottom of the wrong minipage.

picture
=======

     \begin{picture}(WIDTH,HEIGHT)(XOFFSET,YOFFSET)
     ... PICTURE COMMANDS ...
     \end{picture}

The picture environment allows you to create just about any kind of picture you want containing text, lines, arrows and circles. You tell LaTeX where to put things in the picture by specifying their coordinates.  A coordinate is a number that may have a decimal point and a minus sign---a number like 5, 0.3 or -3.1416.  A coordinate specifies a length in multiples of the unit length \unitlength, so if \unitlength has been set to 1cm, then the coordinate 2.54 specifies a length of 2.54 centimeters.

You should only change the value of \unitlength, using the \setlength command, outside of a picture environment. The default value is 1pt.

The picture package redefine the picture environment so that everywhere a number is used in a PICTURE COMMANDS to specify a coordinate, one can use alternatively a length. Be aware however that this will prevent scaling those lengths by changing \unitlength.

A position is a pair of coordinates, such as (2.4,-5), specifying the point with x-coordinate 2.4 and y-coordinate -5. Coordinates are specified in the usual way with respect to an origin, which is normally at the lower-left corner of the picture.  Note that when a position appears as an argument, it is not enclosed in braces; the parentheses serve to delimit the argument.

The picture environment has one mandatory argument which is a position (WIDTH,HEIGHT), which specifies the size of the picture.  The environment produces a rectangular box with these WIDTH and HEIGHT.

The picture environment also has an optional position argument (XOFFSET,YOFFSET), following the size argument, that can change the origin.  (Unlike ordinary optional arguments, this argument is not contained in square brackets.) The optional argument gives the coordinates of the point at the lower-left corner of the picture (thereby determining the origin).  For example, if \unitlength has been set to 1mm, the command

     \begin{picture}(100,200)(10,20)

produces a picture of width 100 millimeters and height 200 millimeters, whose lower-left corner is the point (10,20) and whose upper-right corner is therefore the point (110,220).  When you first draw a picture, you typically omit the optional argument, leaving the origin at the lower-left corner.  If you then want to modify your picture by shifting everything, you can just add the appropriate optional argument.

The environment's mandatory argument determines the nominal size of the picture.  This need bear no relation to how large the picture really is; LaTeX will happily allow you to put things outside the picture, or even off the page.  The picture's nominal size is used by LaTeX in determining how much room to leave for it.

Everything that appears in a picture is drawn by the \put command. The command

     \put (11.3,-.3){...}

puts the object specified by ... in the picture, with its reference point at coordinates (11.3,-.3). The reference points for various objects will be described below.

The \put command creates an LR box.  You can put anything that can go in an \mbox (see \mbox) in the text argument of the \put command.  When you do this, the reference point will be the lower left corner of the box.

The picture commands are described in the following sections.

\circle
-------

Synopsis:

     \circle[*]{DIAMETER}

The \circle command produces a circle with a diameter as close to the specified one as possible.  The *-form of the command draws a solid circle.

Circles up to 40pt can be drawn.

\makebox
--------

Synopsis:

     \makebox(WIDTH,HEIGHT)[POSITION]{TEXT}

The \makebox command for the picture environment is similar to the normal \makebox command except that you must specify a WIDTH and HEIGHT in multiples of \unitlength.

The optional argument, [POSITION], specifies the quadrant that your TEXT appears in.  You may select up to two of the following:

t
     Moves the item to the top of the rectangle.

b
     Moves the item to the bottom.

l
     Moves the item to the left.

r
     Moves the item to the right.

See \makebox.

\framebox
---------

Synopsis:

     \framebox(WIDTH,HEIGHT)[POS]{...}

The \framebox command is like \makebox (see previous section), except that it puts a frame around the outside of the box that it creates.

The \framebox command produces a rule of thickness \fboxrule, and leaves a space \fboxsep between the rule and the contents of the box.

\dashbox
--------

Draws a box with a dashed line.  Synopsis:

     \dashbox{DLEN}(RWIDTH,RHEIGHT)[POS]{TEXT}

\dashbox creates a dashed rectangle around TEXT in a picture environment.  Dashes are DLEN units long, and the rectangle has overall width RWIDTH and height RHEIGHT. The TEXT is positioned at optional POS.

A dashed box looks best when the RWIDTH and RHEIGHT are multiples of the DLEN.

\frame
------

Synopsis:

     \frame{TEXT}

The \frame command puts a rectangular frame around TEXT. The reference point is the bottom left corner of the frame.  No extra space is put between the frame and the object.

\line
-----

Synopsis:

     \line(XSLOPE,YSLOPE){LENGTH}

The \line command draws a line with the given LENGTH and slope XSLOPE/YSLOPE.

Standard LaTeX can only draw lines with SLOPE = x/y, where x and y have integer values from -6 through 6.  For lines of any slope, and plenty of other shapes, see pict2e and many other packages on CTAN.

\linethickness
--------------

The \linethickness{DIM} command declares the thickness of horizontal and vertical lines in a picture environment to be DIM, which must be a positive length.

\linethickness does not affect the thickness of slanted lines, circles, or the quarter circles drawn by \oval.

\thicklines
-----------

The \thicklines command is an alternate line thickness for horizontal and vertical lines in a picture environment; cf. \linethickness and \thinlines.

\thinlines
----------

The \thinlines command is the default line thickness for horizontal and vertical lines in a picture environment; cf. \linethickness and \thicklines.

\multiput
---------

Synopsis:

     \multiput(X,Y)(DELTA_X,DELTA_Y){N}{OBJ}

The \multiput command copies the object OBJ in a regular pattern across a picture.  OBJ is first placed at position (x,y), then at (x+\delta x,y+\delta y), and so on, N times.

\oval
-----

Synopsis:

     \oval(WIDTH,HEIGHT)[PORTION]

The \oval command produces a rectangle with rounded corners.  The optional argument PORTION allows you to produce only half of the oval via the following:

t
     selects the top half;

b
     selects the bottom half;

r
     selects the right half;

l
     selects the left half.

It is also possible to produce only one quarter of the oval by setting PORTION to tr, br, bl, or tl.

The ``corners'' of the oval are made with quarter circles with a maximum radius of 20pt, so large ``ovals'' will look more like boxes with rounded corners.

\put
----

Synopsis:

     \put(XCOORD,YCOORD){ ... }

The \put command places the material specified by the (mandatory) argument in braces at the given coordinate, (XCOORD,YCOORD).

\shortstack
-----------

Synopsis:

     \shortstack[POSITION]{...\\...\\...}

The \shortstack command produces a stack of objects.  The valid positions are:

r
     Move the objects to the right of the stack.

l
     Move the objects to the left of the stack

c
     Move the objects to the centre of the stack (default)

Objects are separated with \\.

\vector
-------

Synopsis:

     \vector(XSLOPE,YSLOPE){LENGTH}

The \vector command draws a line with an arrow of the specified length and slope.  The XSLOPE and YSLOPE values must lie between -4 and +4, inclusive.

quotation and quote
===================

Synopsis:

     \begin{quotation}
     TEXT
     \end{quotation}

or

     \begin{quote}
     TEXT
     \end{quote}

Include a quotation.

In both environments, margins are indented on both sides by \leftmargin and the text is justified at both.  As with the main text, leaving a blank line produces a new paragraph.

To compare the two: in the quotation environment, paragraphs are indented by 1.5em and the space between paragraphs is small, 0pt plus 1pt.  In the quote environment, paragraphs are not indented and there is vertical space between paragraphs (it is the rubber length \parsep).  Thus, the quotation environment may be more suitable for documents where new paragraphs are marked by an indent rather than by a vertical separation.  In addition, quote may be more suitable for a short quotation or a sequence of short quotations.

     \begin{quotation}
     \it Four score and seven years ago
       ... shall not perish from the earth.
     \hspace{1em plus 1fill}---Abraham Lincoln
     \end{quotation}

tabbing
=======

Synopsis:

     \begin{tabbing}
     ROW1COL1 \= ROW1COL2 ...  \\
     ROW2COL1 \> ROW2COL2 ...  \\
     ...
     \end{tabbing}

The tabbing environment aligns text in columns.  It works by setting tab stops and tabbing to them much as was done on a typewriter. It is best suited for cases where the width of each column is constant and known in advance.

This example has a first line where the tab stops are set to explicit widths, ended by a \kill command (which is described below):

     \begin{tabbing}
     \hspace{0.75in}     \= \hspace{0.40in}  \= \hspace{0.40in}    \kill
     Ship                \> Guns             \> Year    \\
     \textit{Sophie}     \> 14               \> 1800    \\
     \textit{Polychrest} \> 24               \> 1803    \\
     \textit{Lively}     \> 38               \> 1804    \\
     \textit{Surprise}   \> 28               \> 1805    \\
     \end{tabbing}

Both the tabbing environment and the more widely-used tabular environment put text in columns.  The most important distinction is that in tabular the width of columns is determined automatically by LaTeX, while in tabbing the user sets the tab stops.  Another distinction is that tabular generates a box, but tabbing can be broken across pages. Finally, while tabular can be used in any mode, tabbing can be used only in paragraph mode and it starts a new paragraph.

A tabbing environment always starts a new paragraph, without indentation. Moreover, as shown in the example above, there is no need to use the starred form of the \hspace command at the beginning of a tabbed row.  The right margin of the tabbing environment is the end of line, so that the width of the environment is \linewidth.

The tabbing environment contains a sequence of tabbed rows.  The first tabbed row begins immediately after \begin{tabbing} and each row ends with \\ or \kill. The last row may omit the \\ and end with just \end{tabbing}.

At any point the tabbing environment has a current tab stop pattern, a sequence of N > 0 tab stops, numbered 0, 1, etc.  These create N corresponding columns.  Tab stop 0 is always the left margin, defined by the enclosing environment.  Tab stop number I is set if it is assigned a horizontal position on the page.  Tab stop number I can only be set if all the stops 0, ..., i-1 have already been set; normally later stops are to the right of earlier ones.

By default any text typeset in a tabbing environment is typeset ragged right and left-aligned on the current tab stop. Typesetting is done in LR mode (see Modes).

The following commands can be used inside a tabbing environment. They are all fragile (see \protect).

\\ (tabbing)
     End a tabbed line and typeset it.

\= (tabbing)
     Sets a tab stop at the current position.

\> (tabbing)
     Advances to the next tab stop.

\<
     Put following text to the left of the local margin (without changing the margin).  Can only be used at the start of the line.

\+
     Moves the left margin of the next and all the following commands one tab stop to the right, beginning tabbed line if necessary.

\-
     Moves the left margin of the next and all the following commands one tab stop to the left, beginning tabbed line if necessary.

\' (tabbing)
     Moves everything that you have typed so far in the current column, i.e., everything from the most recent \>, \<, \', \\, or \kill command, to the previous column and aligned to the right, flush against the current column's tab stop.

\` (tabbing)
     Allows you to put text flush right against any tab stop, including tab stop 0.  However, it can't move text to the right of the last column because there's no tab stop there.  The \` command moves all the text that follows it, up to the \\ or \end{tabbing} command that ends the line, to the right margin of the tabbing environment.  There must be no \> or \' command between the \` and the \\ or \end{tabbing} command that ends the line.

\a (tabbing)
     In a tabbing environment, the commands \=, \' and \` do not produce accents as usual (see Accents).  Instead, use the commands \a=, \a' and \a`.

\kill
     Sets tab stops without producing text.  Works just like \\ except that it throws away the current line instead of producing output for it. Any \=, \+ or \- commands in that line remain in effect.

\poptabs
     Restores the tab stop positions saved by the last \pushtabs.

\pushtabs
     Saves all current tab stop positions. Useful for temporarily changing tab stop positions in the middle of a tabbing environment.

\tabbingsep
     Distance of the text moved by \' to left of current tab stop.

This example typesets a Pascal function:

     \begin{tabbing}
     function \= fact(n : integer) : integer;\\
              \> begin \= \+ \\
                    \> if \= n > 1 then \+ \\
                             fact := n * fact(n-1) \- \\
                       else \+ \\
                             fact := 1; \-\- \\
                 end;\\
     \end{tabbing}

The output looks like this:

     function fact(n : integer) : integer;
              begin
                    if n > 1 then
                       fact := n * fact(n-1);
                    else
                       fact := 1;
              end;

algorithm2e listings minted

(The above example is just for illustration of the environment.  To actually typeset computer code in typewriter like this, a verbatim environment (see verbatim) would normally suffice.  For pretty-printed code, there are quite a few packages, including algorithm2e, fancyvrb, listings, and minted.)

table
=====

Synopsis:

     \begin{table}[PLACEMENT]
       table body
     \caption[LOFTITLE]{TITLE}
     \label{LABEL}
     \end{table}

A class of floats (see Floats).  Because they cannot be split across pages, they are not typeset in sequence with the normal text but instead are ``floated'' to a convenient place, such as the top of a following page.

For the possible values of PLACEMENT and their effect on the float placement algorithm, see Floats.

The table body is typeset in a parbox of width \textwidth and so it can contain text, commands, etc.

The label is optional; it is used for cross references (see Cross references). The optional \caption command specifies caption text for the table.  By default it is numbered.  If LOTTITLE is present, it is used in the list of tables instead of TITLE (see Tables of contents).

In this example the table and caption will float to the bottom of a page, unless it is pushed to a float page at the end.

     \begin{table}[b]
       \centering
       \begin{tabular}{r|p{2in}} \hline
         One &The loneliest number \\
         Two &Can be as sad as one.
              It's the loneliest number since the number one.
       \end{tabular}
       \caption{Cardinal virtues}
       \label{tab:CardinalVirtues}
     \end{table}

tabular
=======

Synopsis:

     \begin{tabular}[POS]{COLS}
     column 1 entry &column 2 entry ... &column n entry \\
       ...
     \end{tabular}

or

     \begin{tabular*}{WIDTH}[POS]{COLS}
     column 1 entry &column 2 entry ... &column n entry \\
       ...
     \end{tabular*}

These environments produce a table, a box consisting of a sequence of horizontal rows.  Each row consists of items that are aligned vertically in columns.  This illustrates many of the features.

     \begin{tabular}{l|l}
       \textit{Player name}  &\textit{Career home runs}  \\
       \hline
       Hank Aaron  &755 \\
       Babe Ruth   &714
     \end{tabular}

The vertical format of two left-aligned columns, with a vertical bar between them, is specified in tabular's argument {l|l}. Columns are separated with an ampersand &.  A horizontal rule between two rows is created with \hline. The end of each row is marked with a double backslash \\. This \\ is optional after the last row unless an \hline command follows, to put a rule below the table.

The required and optional arguments to tabular consist of:

width
     Required for tabular*, not allowed for tabular. Specifies the width of the tabular* environment.  The space between columns should be rubber, as with @{\extracolsep{\fill}}, to allow the table to stretch or shrink to make the specified width, or else you are likely to get the Underfull \hbox (badness 10000) in alignment ... warning.

pos
     Optional.  Specifies the table's vertical position.  The default is to align the table so its vertical center matches the baseline of the surrounding text.  There are two other possible alignments: t aligns the table so its top row matches the baseline of the surrounding text, and b aligns on the bottom row.

     This only has an effect if there is other text.  In the common case of a tabular alone in a center environment this option makes no difference.

cols
     Required.  Specifies the formatting of columns.  It consists of a sequence of the following specifiers, corresponding to the types of column and intercolumn material.

     l
          A column of left-aligned items.

     r
          A column of right-aligned items.

     c
          A column of centered items.

     |
          A vertical line the full height and depth of the environment.

     @{TEXT OR SPACE}
          This inserts TEXT OR SPACE at this location in every row.  The TEXT OR SPACE material is typeset in LR mode.  This text is fragile (see \protect).

          This specifier is optional: with no @-expression, LaTeX's book, article, and report classes will put on either side of each column a space of length \tabcolsep, which by default is 6pt.  That is, by default adjacent columns are separated by 12pt (so \tabcolsep is misleadingly-named since it is not the separation between tabular columns).  By implication, a space of 6pt also comes before the first column and after the final column, unless you put a @{...} or | there.

          If you override the default and use an @-expression then you must insert any desired space yourself, as in @{\hspace{1em}}.

          An empty expression @{} will eliminate the space, including the space at the start or end, as in the example below where the tabular lines need to lie on the left margin.

               \begin{flushleft}
                 \begin{tabular}{@{}l}
                   ...
                 \end{tabular}
               \end{flushleft}

          This example shows text, a decimal point, between the columns, arranged so the numbers in the table are aligned on that decimal point.

               \begin{tabular}{r@{$.$}l}
                 $3$ &$14$  \\
                 $9$ &$80665$
               \end{tabular}

          An \extracolsep{WD} command in an @-expression causes an extra space of width WD to appear to the left of all subsequent columns, until countermanded by another \extracolsep command. Unlike ordinary intercolumn space, this extra space is not suppressed by an @-expression.  An \extracolsep command can be used only in an @-expression in the cols argument.  Below, LaTeX inserts the right amount of intercolumn space to make the entire table 4 inches wide.

               \begin{center}
                 \begin{tabular*}{4in}{l@{\ \ldots\extracolsep{\fill}}l}
                   Seven times down, eight times up
                   &such is life!
                 \end{tabular*}
               \end{center}

          To insert commands that are automatically executed before a given column, load the array package and use the >{...} specifier.

     p{WD}
          Each item in the column is typeset in a parbox of width WD.

          Note that a line break double backslash \\ may not appear in the item, except inside an environment like minipage, array, or tabular, or inside an explicit \parbox, or in the scope of a \centering, \raggedright, or \raggedleft declaration (when used in a p-column element these declarations must appear inside braces, as with {\centering .. \\ ..}). Otherwise LaTeX will misinterpret the double backslash as ending the row.

     *{NUM}{COLS}
          Equivalent to NUM copies of COLS, where NUM is a positive integer and COLS is a list of specifiers.  Thus \begin{tabular}{|*{3}{l|r}|} is equivalent to \begin{tabular}{|l|rl|rl|r|}.  Note that COLS may contain another *-expression.

Parameters that control formatting:

\arrayrulewidth
     A length that is the thickness of the rule created by |, \hline, and \vline in the tabular and array environments.  The default is .4pt. Change it as in \setlength{\arrayrulewidth}{0.8pt}.

\arraystretch
     A factor by which the spacing between rows in the tabular and array environments is multiplied.  The default is 1, for no scaling.  Change it as \renewcommand{\arraystretch}{1.2}.

\doublerulesep
     A length that is the distance between the vertical rules produced by the || specifier.  The default is 2pt.

\tabcolsep
     A length that is half of the space between columns. The default is 6pt.  Change it with \setlength.

The following commands can be used inside the body of a tabular environment, the first two inside an entry and the second two between lines:

\multicolumn
------------

Synopsis:

     \multicolumn{NUMCOLS}{COLS}{TEXT}

Make an array or tabular entry that spans several columns. The first argument NUMCOLS gives the number of columns to span. The second argument COLS specifies the formatting of the entry, with c for centered, l for flush left, or r for flush right.  The third argument TEXT gives the contents of that entry.

In this example, in the first row, the second and third columns are spanned by the single heading Name.

     \begin{tabular}{lccl}
       \textit{ID}       &\multicolumn{2}{c}{\textit{Name}} &\textit{Age} \\ \hline % row one
       978-0-393-03701-2 &O'Brian &Patrick                  &55           \\        % row two
         ...
     \end{tabular}

What counts as a column is: the column format specifier for the array or tabular environment is broken into parts, where each part (except the first) begins with l, c, r, or p.  So from \begin{tabular}{|r|ccp{1.5in}|} the parts are |r|, c, c, and p{1.5in}|.

The COLS argument overrides the array or tabular environment's intercolumn area default adjoining this multicolumn entry. To affect that area, this argument can contain vertical bars | indicating the placement of vertical rules, and @{...} expressions.  Thus if COLS is |c| then this multicolumn entry will be centered and a vertical rule will come in the intercolumn area before it and after it.  This table details the exact behavior.

     \begin{tabular}{|cc|c|c|}
       \multicolumn{1}{r}{w}       % entry one
         &\multicolumn{1}{|r|}{x}  % entry two
         &\multicolumn{1}{|r}{y}   % entry three
         &z                        % entry four
     \end{tabular}

Before the first entry the output will not have a vertical rule because the \multicolumn has the COLS specifier r with no initial vertical bar.  Between entry one and entry two there will be a vertical rule; although the first COLS does not have an ending vertical bar, the second COLS does have a starting one.  Between entry two and entry three there is a single vertical rule; despite that the COLS in both of the surrounding multicolumn's call for a vertical rule, you only get one rule.  Between entry three and entry four there is no vertical rule; the default calls for one but the COLS in the entry three \multicolumn leaves it out, and that takes precedence.  Finally, following entry four there is a vertical rule because of the default.

The number of spanned columns NUMCOLS can be 1.  Besides giving the ability to change the horizontal alignment, this also is useful to override for one row the tabular definition's default intercolumn area specification, including the placement of vertical rules.

In the example below, in the tabular definition the first column is specified to default to left justified but in the first row the entry is centered with \multicolumn{1}{c}{\textsc{Period}}. Also in the first row, the second and third columns are spanned by a single entry with \multicolumn{2}{c}{\textsc{Span}}, overriding the specification to center those two columns on the page range en-dash.

     \begin{tabular}{l|r@{--}l}
       \multicolumn{1}{c}{\textsc{Period}}
         &multicolumn{2}{c}{\textsc{Span}} \\ \hline
       Baroque          &1600           &1760         \\
       Classical        &1730           &1820         \\
       Romantic         &1780           &1910         \\
       Impressionistic  &1875           &1925
     \end{tabular}

Note that although the tabular specification by default puts a vertical rule between the first and second columns, because there is no vertical bar in the COLS of either of the first row's \multicolumn commands, no rule appears in the first row.

\vline
------

Draw a vertical line in a tabular or array environment extending the full height and depth of an entry's row.  Can also be used in an @-expression, although its synonym vertical bar | is more common.  This command is rarely used in the body of a table; typically a table's vertical lines are specified in tabular's COLS argument and overridden as needed with \multicolumn.

This example illustrates some pitfalls.  In the first line's second entry the \hfill moves the \vline to the left edge of the cell.  But that is different than putting it halfway between the two columns, so in that row between the first and second columns there are two vertical rules, with the one from the {c|cc} specifier coming before the one produced by the \vline\hfill.  In contrast, the first line's third entry shows the usual way to put a vertical bar between two columns.  In the second line, the ghi is the widest entry in its column so in the \vline\hfill the \hfill has no effect and the vertical line in that entry appears immediately next to the g, with no whitespace.

     \begin{tabular}{c|cc}
       x   &\vline\hfill y   &\multicolumn{1}{|r}{z} \\
       abc &def &\vline\hfill ghi
     \end{tabular}

\cline
------

Synopsis:

     \cline{I-J}

Draw a horizontal rule in an array or tabular environment beginning in column I and ending in column J. The dash - must appear in the mandatory argument. To span a single column use the number twice.

This example puts two horizontal lines between the first and second rows, one line in the first column only, and the other spanning the third and fourth columns.  The two lines are side-by-side, at the same height.

     \begin{tabular}{llrr}
       a &b &c &d \\ \cline{1-1} \cline{3-4}
       e &f &g &h
     \end{tabular}

\hline
------

Draws a horizontal line the width of the enclosing tabular or array environment.  It's most commonly used to draw a line at the top, bottom, and between the rows of a table.

In this example the top of the table has two horizontal rules, one above the other, that span both columns.  The bottom of the table has a single rule spanning both columns.  Because of the \hline, the tabular second row's line ending double backslash \\ is required.

     \begin{tabular}{ll} \hline\hline
       Baseball   &Red Sox  \\
       Basketball &Celtics  \\ \hline
     \end{tabular}

thebibliography
===============

Synopsis:

     \begin{thebibliography}{WIDEST-LABEL}
     \bibitem[LABEL]{CITE_KEY}
     ...
     \end{thebibliography}

The thebibliography environment produces a bibliography or reference list.

In the article class, this reference list is labelled References and the label is stored in macro \refname; in the report class, it is labelled Bibliography and the label is stored in macro \bibname.

You can change the label by redefining the command \refname or \bibname, whichever is applicable depending on the class:

  * For standard classes whose top level sectioning is \chapter (such as book and report), the label is in the macro \bibname;

  * For standard classes whose the top level sectioning is \section (such as article), the label is in macro \refname.

Typically it is neither necessary nor desirable to directly redefine \refname or \bibname; language support packages like babel do this.

The mandatory WIDEST-LABEL argument is text that, when typeset, is as wide as the widest item label produced by the \bibitem commands.  It is typically given as 9 for bibliographies with less than 10 references, 99 for ones with less than 100, etc.

\bibitem
--------

Synopsis:

     \bibitem[LABEL]{CITE_KEY}

The \bibitem command generates an entry labelled by LABEL. If the LABEL argument is missing, a number is automatically generated using the enumi counter.  The CITE_KEY is a citation key consisting in any sequence of letters, numbers, and punctuation symbols not containing a comma.

This command writes an entry to the .aux file containing the item's CITE_KEY and LABEL.  When the .aux file is read by the \begin{document} command, the item's LABEL is associated with cite_key, causing references to CITE_KEY with a \cite command (see \cite) to produce the associated LABEL.

\cite
-----

Synopsis:

     \cite[SUBCITE]{KEYS}

The KEYS argument is a list of one or more citation keys (see \bibitem), separated by commas.  This command generates an in-text citation to the references associated with KEYS by entries in the .aux file.

The text of the optional SUBCITE argument appears after the citation.  For example, \cite[p.~314]{knuth} might produce [Knuth, p. 314].

\nocite
-------

Synopsis:

     \nocite{KEYS}

The \nocite command produces no text, but writes KEYS, which is a list of one or more citation keys, to the .aux file.

Using BibTeX
------------

If you use the BibTeX program by Oren Patashnik (highly recommended if you need a bibliography of more than a couple of titles) to maintain your bibliography, you don't use the thebibliography environment (see thebibliography). Instead, you include the lines

     \bibliographystyle{BIBSTYLE}
     \bibliography{BIBFILE1,BIBFILE2}

The \bibliographystyle command does not produce any output of its own.  Rather, it defines the style in which the bibliography will be produced: BIBSTYLE refers to a file BIBSTYLE.bst, which defines how your citations will look. The standard BIBSTYLE names distributed with BibTeX are:

alpha
     Sorted alphabetically. Labels are formed from name of author and year of publication.

plain
     Sorted alphabetically. Labels are numeric.

unsrt
     Like plain, but entries are in order of citation.

abbrv
     Like plain, but more compact labels.

In addition, numerous other BibTeX style files exist tailored to the demands of various publications.  See http://mirror.ctan.org/biblio/bibtex/contrib.

The \bibliography command is what actually produces the bibliography.  The argument to \bibliography refers to files named BIBFILE1.bib, BIBFILE2.bib, ..., which should contain your database in BibTeX format.  Only the entries referred to via \cite and \nocite will be listed in the bibliography.

theorem
=======

Synopsis:

     \begin{theorem}
     THEOREM-TEXT
     \end{theorem}

The theorem environment produces ``Theorem N'' in boldface followed by THEOREM-TEXT, where the numbering possibilities for N are described under \newtheorem (see \newtheorem).

titlepage
=========

Synopsis:

     \begin{titlepage}
       ... text and spacing ...
     \end{titlepage}

Create a title page, a page with no printed page number or heading.  The following page will be numbered page one.

To instead produce a standard title page without a titlepage environment you can use \maketitle (see \maketitle).

Notice in this example that all formatting, including vertical spacing, is left to the author.

     \begin{titlepage}
     \vspace*{\stretch{1}}
     \begin{center}
       {\huge\bfseries Thesis \\[1ex]
                       title}                  \\[6.5ex]
       {\large\bfseries Author name}           \\
       \vspace{4ex}
       Thesis  submitted to                    \\[5pt]
       \textit{University name}                \\[2cm]
       in partial fulfilment for the award of the degree of \\[2cm]
       \textsc{\Large Doctor of Philosophy}    \\[2ex]
       \textsc{\large Mathematics}             \\[12ex]
       \vfill
       Department of Mathematics               \\
       Address                                 \\
       \vfill
       \today
     \end{center}
     \vspace{\stretch{2}}
     \end{titlepage}

verbatim
========

Synopsis:

     \begin{verbatim}
     LITERAL-TEXT
     \end{verbatim}

The verbatim environment is a paragraph-making environment in which LaTeX produces exactly what you type in; for instance the \ character produces a printed \.  It turns LaTeX into a typewriter with carriage returns and blanks having the same effect that they would on a typewriter.

The verbatim environment uses a monospaced typewriter-like font (\tt).

\verb
-----

Synopsis:

     \verbCHARLITERAL-TEXTCHAR
     \verb*CHARLITERAL-TEXTCHAR

The \verb command typesets LITERAL-TEXT as it is input, including special characters and spaces, using the typewriter (\tt) font.  No spaces are allowed between \verb or \verb* and the delimiter CHAR, which begins and ends the verbatim text.  The delimiter must not appear in LITERAL-TEXT.

The *-form differs only in that spaces are printed with a ``visible space'' character.

verse
=====

Synopsis:

     \begin{verse}
     LINE1 \\
     LINE2 \\
     ...
     \end{verse}

The verse environment is designed for poetry, though you may find other uses for it.

The margins are indented on the left and the right, paragraphs are not indented, and the text is not justified.  Separate the lines of each stanza with \\, and use one or more blank lines to separate the stanzas.

Line breaking
*************

The first thing LaTeX does when processing ordinary text is to translate your input file into a sequence of glyphs and spaces.  To produce a printed document, this sequence must be broken into lines (and these lines must be broken into pages).

LaTeX usually does the line (and page) breaking in the text body for you but in some environments you manually force line breaks.

\\
==

Synopsis:

     \\[MORESPACE]

or

     \\*[MORESPACE]

Start a new line.  The optional argument MORESPACE specifies extra vertical space to be insert before the next line.  This can be a negative length.  The text before the break is set at its normal length, that is, it is not stretched to fill out the line width.

Explicit line breaks in the text body are unusual in LaTeX.  In particular, to start a new paragraph instead leave a blank line.  This command is mostly used outside of the main flow of text such as in a tabular or array environment.

Under ordinary circumstances (e.g., outside of a p{...} column in a tabular environment) the \newline command is a synonym for \\ (see \newline).

In addition to starting a new line, the starred form \\* tells LaTeX not to start a new page between the two lines, by issuing a \nobreak.

     \title{My story: \\[0.25in]
            a tale of woe}

\obeycr & \restorecr
====================

The \obeycr command makes a return in the input file (^^M, internally) the same as \\ (followed by \relax).  So each new line in the input will also be a new line in the output.

\restorecr restores normal line-breaking behavior.

\newline
========

In ordinary text this is equivalent to double-backslash (see \\); it breaks a line, with no stretching of the text before it.

Inside a tabular or array environment, in a column with a specifier producing a paragraph box, like typically p{...}, \newline will insert a line break inside of the column, that is, it does not break the entire row.  To break the entire row use \\ or its equivalent \tabularnewline.

This will print Name: and Address: as two lines in a single cell of the table.

     \begin{tabular}{p{1in}{\hspace{2in}}p{1in}}
       Name: \newline Address: &Date: \\ \hline
     \end{tabular}

The Date: will be baseline-aligned with Name:.

\- (discretionary hyphen)
=========================

The \- command tells LaTeX that it may hyphenate the word at that point.  LaTeX is pretty good at hyphenating, and usually finds most of the correct hyphenation points, while almost never using an incorrect one.  The \- command is used for the exceptional cases.

When you insert \- commands in a word, the word will only be hyphenated at those points and not at any of the hyphenation points that LaTeX might otherwise have chosen.

\discretionary (generalized hyphenation point)
==============================================

Synopsis:

     \discretionary{PRE-BREAK-TEXT}{POST-BREAK-TEXT}{NO-BREAK-TEXT}

\fussy
======

The declaration \fussy (which is the default) makes TeX picky about line breaking.  This usually avoids too much space between words, at the cost of an occasional overfull box.

This command cancels the effect of a previous \sloppy command (see \sloppy).

\sloppy
=======

The declaration \sloppy makes TeX less fussy about line breaking. This will avoid overfull boxes, at the cost of loose interword spacing.

Lasts until a \fussy command is issued (see \fussy).

\hyphenation
============

Synopsis:

     \hyphenation{WORD-ONE WORD-TWO}

The \hyphenation command declares allowed hyphenation points with a - character in the given words.  The words are separated by spaces.  TeX will only hyphenate if the word matches exactly, no inflections are tried.  Multiple \hyphenation commands accumulate.  Some examples (the default TeX hyphenation patterns misses the hyphenations in these words):

     \hyphenation{ap-pen-dix col-umns data-base data-bases}

\linebreak & \nolinebreak
=========================

Synopses:

     \linebreak[PRIORITY]
     \nolinebreak[PRIORITY]

By default, the \linebreak (\nolinebreak) command forces (prevents) a line break at the current position.  For \linebreak, the spaces in the line are stretched out so that it extends to the right margin as usual.

With the optional argument PRIORITY, you can convert the command from a demand to a request.  The PRIORITY must be a number from 0 to 4.  The higher the number, the more insistent the request.

Page breaking
*************

LaTeX starts new pages asynchronously, when enough material has accumulated to fill up a page.  Usually this happens automatically, but sometimes you may want to influence the breaks.

\cleardoublepage
================

The \cleardoublepage command ends the current page and causes all the pending floating figures and tables that have so far appeared in the input to be printed.  In a two-sided printing style, it also makes the next page a right-hand (odd-numbered) page, producing a blank page if necessary.

\clearpage
==========

The \clearpage command ends the current page and causes all the pending floating figures and tables that have so far appeared in the input to be printed.

\newpage
========

The \newpage command ends the current page, but does not clear floats (see \clearpage).

\enlargethispage
================

\enlargethispage{size}

\enlargethispage*{size}

Enlarge the \textheight for the current page by the specified amount; e.g., \enlargethispage{\baselineskip} will allow one additional line.

The starred form tries to squeeze the material together on the page as much as possible. This is normally used together with an explicit \pagebreak.

\pagebreak & \nopagebreak
=========================

Synopses:

     \pagebreak[PRIORITY]
     \nopagebreak[PRIORITY]

By default, the \pagebreak (\nopagebreak) command forces (prevents) a page break at the current position.  With \pagebreak, the vertical space on the page is stretched out where possible so that it extends to the normal bottom margin.

With the optional argument PRIORITY, you can convert the \pagebreak command from a demand to a request.  The number must be a number from 0 to 4.  The higher the number, the more insistent the request is.

Footnotes
*********

Place a numbered footnote at the bottom of the current page, as here.

     Noël Coward quipped that having to read a footnote is like having
     to go downstairs to answer the door, while in the midst of making
     love.\footnote{I wouldn't know, I don't read footnotes.}

You can place multiple footnotes on a page. If the text becomes too long it will flow to the next page.

You can also produce footnotes by combining the \footnotemark and the \footnotetext commands, which is useful in special circumstances.

To make bibliographic references come out as footnotes you need to include a bibliographic style with that behavior.

\footnote
=========

Synopsis:

     \footnote[NUMBER]{TEXT}

Place a numbered footnote TEXT at the bottom of the current page.

     There are over a thousand footnotes in Gibbon's
     \textit{Decline and Fall of the Roman Empire}.\footnote{After
     reading an early version with endnotes David Hume complained,
     ``One is also plagued with his Notes, according to the present Method
     of printing the Book'' and suggested that they ``only to be printed
     at the Margin or the Bottom of the Page.''}

The optional argument NUMBER allows you to specify the footnote number.  If you use this option then the footnote number counter is not incremented, and if you do not use it then the counter is incremented.

Change how LaTeX shows the footnote counter with something like \renewcommand{\thefootnote}{\fnsymbol{footnote}}, which uses a sequence of symbols (see \alph \Alph \arabic \roman \Roman \fnsymbol).  To make this change global put that in the preamble.  If you make the change local then you may want to reset the counter with \setcounter{footnote}{0}.  By default LaTeX uses arabic numbers.

LaTeX's default puts many restrictions on where you can use a \footnote; for instance, you cannot use it in an argument to a sectioning command such as \chapter (it can only be used in outer paragraph mode).  There are some workarounds; see following sections.

In a minipage environment the \footnote command uses the mpfootnote counter instead of the footnote counter, so they are numbered independently.  They are shown at the bottom of the environment, not at the bottom of the page. And by default they are shown alphabetically. See minipage.

\footnotemark
=============

Synopsis, one of:

     \footnotemark
     \footnotemark[NUMBER]

Put the current footnote number in the text. (See \footnotetext for giving the text of the footnote separately.)  The version with the optional argument NUMBER uses that number to determine the mark printed. This command can be used in inner paragraph mode.

This example gives the same institutional affiliation to both the first and third authors (\thanks is a version of footnote).

     \title{A Treatise on the Binomial Theorem}
     \author{J Moriarty\thanks{University of Leeds}
       \and A C Doyle\thanks{Durham University}
       \and S Holmes\footnotemark[1]}
     \begin{document}
     \maketitle

If you use \footnotemark without the optional argument then it increments the footnote counter but if you use the optional NUMBER then it does not. This produces several consecutive footnote markers referring to the same footnote.

     The first theorem\footnote{Due to Gauss.}
     and the second theorem\footnotemark[\value{footnote}]
     and the third theorem.\footnotemark[\value{footnote}]

\footnotetext
=============

Synopsis, one of:

     \footnotetext{TEXT}
     \footnotetext[NUMBER]{TEXT}

Place TEXT at the bottom of the page as a footnote.  This command can come anywhere after the \footnotemark command.  The optional argument NUMBER changes the displayed footnote number.  The \footnotetext command must appear in outer paragraph mode.

Footnotes in a table
====================

Inside a table environment the \footnote command does not work.  For instance, if the code below appears on its own then the footnote simply disappears; there is a footnote mark in the table cell but nothing is set at the bottom of the page.

     \begin{center}
          \begin{tabular}{l|l}
          \textsc{Ship}  &\textsc{Book} \\ \hline
          \textit{HMS Sophie}     &Master and Commander  \\
          \textit{HMS Polychrest} &Post Captain  \\
          \textit{HMS Lively}     &Post Captain \\
          \textit{HMS Surprise}   &A number of books\footnote{Starting with
                                     HMS Surprise.}
          \end{tabular}
     \end{center}

The solution is to surround the tabular environment with a minipage environment, as here (see minipage).

     \begin{center}
       \begin{minipage}{.5\textwidth}
         ... tabular material ...
       \end{minipage}
     \end{center}

The same technique will work inside a floating table environment (see table).  To get the footnote at the bottom of the page use the tablefootnote package, as illustrated in this example.  If you put \usepackage{tablefootnote} in the preamble and use the code shown then the footnote appears at the bottom and is numbered in sequence with other footnotes.

     \begin{table}
       \centering
          \begin{tabular}{l|l}
          \textsc{Date}  &\textsc{Campaign} \\ \hline
          1862           &Fort Donelson \\
          1863           &Vicksburg     \\
          1865           &Army of Northern Virginia\footnote{Ending the war.}
          \end{tabular}
         \caption{Forces captured by US Grant}
     \end{table}

Footnotes in section headings
=============================

Putting a footnote in a section heading, as in:

     \section{Full sets\protect\footnote{This material due to ...}}

causes the footnote to appear at the bottom of the page where the section starts, as usual, but also at the bottom of the table of contents, where it is not likely to be desired.  To have it not appear on the table of contents use the package footmisc with the stable option.

     \usepackage[stable]{footmisc}
     ...
     \begin{document}
     ...
     \section{Full sets\footnote{This material due to ...}}

Note that the \protect is gone; including it would cause the footnote to reappear on the table of contents.

Footnotes of footnotes
======================

Particularly in the humanities, authors can have multiple classes of footnotes, including having footnotes of footnotes.  The package bigfoot extends LaTeX's default footnote mechanism in many ways, including allow these two, as in this example.

     \usepackage{bigfoot}
     \DeclareNewFootnote{Default}
     \DeclareNewFootnote{from}[alph]   % create class \footnotefrom{}
      ...
     \begin{document}
     ...
     The third theorem is a partial converse of the
     second.\footnotefrom{First noted in Wilson.\footnote{Second edition only.}}
     ...

Multiple references to footnotes
================================

You can refer to a single footnote more than once.  This example uses the package cleverref.

     \usepackage{cleveref}[2012/02/15]   % this version of package or later
     \crefformat{footnote}{#2\footnotemark[#1]#3}
     ...
     \begin{document}
     ...
     The theorem is from Evers.\footnote{\label{fn:TE}Tinker and Evers, 1994.}
     The corollary is from Chance.\footnote{Evers and Chance, 1990.}
     But the key lemma is from Tinker.\cref{fn:TE}
     ...

This solution will work with the package hyperref. See \footnotemark for a simpler solution in the common case of multiple authors with the same affiliation.

Footnote parameters
===================

\footnoterule
     Produces the rule separating the main text on a page from the page's footnotes.  Default dimensions: 0.4pt thick (or wide), and 0.4\columnwidth long in the standard document classes (except slides, where it does not appear).

\footnotesep
     The height of the strut placed at the beginning of the footnote.  By default, this is set to the normal strut for \footnotesize fonts (see Font sizes), therefore there is no extra space between footnotes.  This is 6.65pt for 10pt, 7.7pt for 11pt, and 8.4pt for 12pt.

Definitions
***********

LaTeX has support for making new commands of many different kinds.

\newcommand & \renewcommand
===========================

\newcommand and \renewcommand define and redefine a command, respectively.  Synopses:

       \newcommand{\CMD}[NARGS][OPTARGDEFAULT]{DEFN}
       \newcommand*{\CMD}[NARGS][OPTARGDEFAULT]{DEFN}
     \renewcommand{\CMD}[NARGS][OPTARGDEFAULT]{DEFN}
     \renewcommand*{\CMD}[NARGS][OPTARGDEFAULT]{DEFN}

The starred form of these two commands requires that the arguments not contain multiple paragraphs of text (not \long, in plain TeX terms).

cmd
     Required; \CMD is the command name.  For \newcommand, it must not be already defined and must not begin with \end.  For \renewcommand, it must already be defined.

nargs
     Optional; an integer from 0 to 9, specifying the number of arguments that the command can take, including any optional argument.  If this argument is not present, the default is for the command to have no arguments.  When redefining a command, the new version can have a different number of arguments than the old version.

optargdefault
     Optional; if this argument is present then the first argument of defined command \CMD is optional, with default value OPTARGDEFAULT (which may be the empty string).  If this argument is not present then \CMD does not take an optional argument.

     That is, if \CMD is used with square brackets following, as in \CMD[MYVAL], then within DEFN the first positional parameter #1 expands MYVAL.  On the other hand, if \CMD is called without square brackets following, then within DEFN the positional parameter #1 expands to the default OPTARGDEFAULT.  In either case, any required arguments will be referred to starting with #2.

     Omitting [MYVAL] in a call is different from having the square brackets with no contents, as in [].  The former results in #1 expanding to OPTARGDEFAULT; the latter results in #1 expanding to the empty string.

defn
     The text to be substituted for every occurrence of \CMD; the positional parameter #N in DEFN is replaced by the text of the Nth argument.

TeX ignores spaces in the source following an alphabetic control sequence, as in \cmd .  If you actually want a space there, one solution is to type {} after the command (\cmd{} ; another solution is to use an explicit control space (\cmd\ ).

A simple example of defining a new command: \newcommand{\RS}{Robin Smith} results in \RS being replaced by the longer text.

Redefining an existing command is similar: \renewcommand{\qedsymbol}{{\small QED}}.

Here's a command definition with one required argument:

     \newcommand{\defref}[1]{Definition~\ref{#1}}

Then, \defref{def:basis} expands to Definition~\ref{def:basis}, which will ultimately expand to something like Definition~3.14.

An example with two required arguments: \newcommand{\nbym}[2]{$#1 \times #2$} is invoked as \nbym{2}{k}.

An example with an optional argument:

     \newcommand{\salutation}[1][Sir or Madam]{Dear #1:}

Then, \salutation gives Dear Sir or Madam: while \salutation[John] gives Dear John:.  And \salutation[] gives Dear :.

The braces around DEFN do not define a group, that is, they do not delimit the scope of the result of expanding DEFN.  So \newcommand{\shipname}[1]{\it #1} is problematic; in this sentence,

     The \shipname{Monitor} met the \shipname{Merrimac}.

the words met the would incorrectly be in italics.  Another pair of braces in the definition is needed, like this: \newcommand{\shipname}[1]{{\it #1}}.  Those braces are part of the definition and thus do define a group.

\providecommand
===============

Defines a command, as long as no command of this name already exists. Synopses:

     \providecommand{CMD}[NARGS][OPTARGDEFAULT]{DEFN}
     \providecommand*{CMD}[NARGS][OPTARGDEFAULT]{DEFN}

If no command of this name already exists then this has the same effect as \newcommand (see \newcommand & \renewcommand).  If a command of this name already exists then this definition does nothing. This is particularly useful in a style file, or other file that may be loaded more than once.

\newcounter: Allocating a counter
=================================

Synopsis, one of:

     \newcounter{COUNTERNAME}
     \newcounter{COUNTERNAME}[SUPERCOUNTER]

Globally defines a new counter named COUNTERNAME and initialize the new counter to zero.

The name COUNTERNAME must consists of letters only, and does not begin with a backslash.  This name must not already be in use by another counter.

When you use the optional argument [SUPERCOUNTER] then COUNTERNAME will be numbered within, or subsidiary to, the existing counter SUPERCOUNTER.  For example, ordinarily subsection is numbered within section so that any time SUPERCOUNTER is incremented with \stepcounter (see \stepcounter) or \refstepcounter (see \refstepcounter) then COUNTERNAME is reset to zero.

See Counters, for more information about counters.

\newlength: Allocating a length
===============================

Allocate a new length register.  Synopsis:

     \newlength{\ARG}

This command takes one required argument, which must begin with a backslash (\).  It creates a new length register named \ARG, which is a place to hold (rubber) lengths such as 1in plus.2in minus.1in (what plain TeX calls a skip register).  The register gets an initial value of zero.  The control sequence \ARG must not already be defined.

See Lengths, for more about lengths.

\newsavebox: Allocating a box
=============================

Allocate a ``bin'' for holding a box.  Synopsis:

     \newsavebox{\CMD}

Defines \CMD to refer to a new bin for storing boxes. Such a box is for holding typeset material, to use multiple times (see Boxes) or to measure or manipulate.  The name \CMD must start with a backslash (\), and must not be already defined.

The allocation of a box is global.  This command is fragile (see \protect).

\newenvironment & \renewenvironment
===================================

These commands define or redefine an environment ENV, that is, \begin{ENV} BODY \end{ENV}.  Synopses:

        \newenvironment{ENV}[NARGS][OPTARGDEFAULT]{BEGDEFN}{ENDDEFN}
       \newenvironment*{ENV}[NARGS][OPTARGDEFAULT]{BEGDEFN}{ENDDEFN}
      \renewenvironment{ENV}[NARGS][OPTARGDEFAULT]{BEGDEFN}{ENDDEFN}
     \renewenvironment*{ENV}[NARGS][OPTARGDEFAULT]{BEGDEFN}{ENDDEFN}

The starred form of these commands requires that the arguments not contain multiple paragraphs of text.  The body of these environments can still contain multiple paragraphs.

env
     Required; the environment name.  It consists only of letters or the * character, and thus does not begin with backslash (\).  It must not begin with the string end.  For \newenvironment, the name ENV must not be the name of an already existing environment, and also the command \ENV must be undefined.  For \renewenvironment, ENV must be the name of an existing environment.

nargs
     Optional; an integer from 0 to 9 denoting the number of arguments of that the environment will take.  When the environment is used these arguments appear after the \begin, as in \begin{ENV}{ARG1}...{ARGN}.  If this argument is not present then the default is for the environment to have no arguments.  When redefining an environment, the new version can have a different number of arguments than the old version.

optargdefault
     Optional; if this argument is present then the first argument of the defined environment is optional, with default value OPTARGDEFAULT (which may be the empty string).  If this argument is not present then the environment does not take an optional argument.

     That is, when [OPTARGDEFAULT] is present in the environment definition, if \begin{ENV} is used with square brackets following, as in \begin{ENV}[MYVAL], then, within BEGDEFN, the positional parameter #1 expands to MYVAL.  If \begin{ENV} is called without square brackets following, then, within within BEGDEFN, the positional parameter #1 expands to the default OPTARGDEFAULT.  In either case, any required arguments will be referred to starting with #2.

     Omitting [MYVAL] in the call is different from having the square brackets with no contents, as in [].  The former results in #1 expanding to OPTARGDEFAULT; the latter results in #1 expanding to the empty string.

begdefn
     Required; the text expanded at every occurrence of \begin{ENV}.  Within BEGDEF, the Nth positional parameter (i.e., #N) is replaced by the text of the Nth argument.

enddefn
     Required; the text expanded at every occurrence of \end{ENV}.  This may not contain any positional parameters, so #N cannot be used here (but see the final example below).

All environments, that is to say the BEGDEFN code, the environment body and the ENDDEFN code, are processed within a group.  Thus, in the first example below, the effect of the \small is limited to the quote and does not extend to material following the environment.

This example gives an environment like LaTeX's quotation except that it will be set in smaller type:

     \newenvironment{smallquote}{%
       \small\begin{quotation}
     }{%
       \end{quotation}
     }

This one shows the use of arguments; it gives a quotation environment that cites the author:

     \newenvironment{citequote}[1][Shakespeare]{%
       \begin{quotation}
       \noindent\textit{#1}:
     }{%
       \end{quotation}
     }

The author's name is optional, and defaults to Shakespeare. In the document, use the environment like this:

     \begin{citequote}[Lincoln]
       ...
     \end{citequote}

The final example shows how to save the value of an argument to use in ENDDEFN, in this case in a box (see \sbox):

     \newsavebox{\quoteauthor}
     \newenvironment{citequote}[1][Shakespeare]{%
       \sbox\quoteauthor{#1}%
       \begin{quotation}
     }{%
       \hspace{1em plus 1fill}---\usebox{\quoteauthor}
       \end{quotation}
     }

\newtheorem
===========

Define a new theorem-like environment.  Synopses:

     \newtheorem{NAME}{TITLE}
     \newtheorem{NAME}{TITLE}[NUMBERED_WITHIN]
     \newtheorem{NAME}[NUMBERED_LIKE]{TITLE}

Using the first form, \newtheorem{NAME}{TITLE} creates an environment that will be labelled with TITLE.  See the first example below.

The second form \newtheorem{NAME}{TITLE}[NUMBERED_WITHIN] creates an environment whose counter is subordinate to the existing counter NUMBERED_WITHIN (its counter will be reset when NUMBERED_WITHIN is reset).

The third form \newtheorem{NAME}[NUMBERED_LIKE]{TITLE}, with optional argument between the two required arguments, will create an environment whose counter will share the previously defined counter NUMBERED_LIKE.

You can specify one of NUMBERED_WITHIN and NUMBERED_LIKE, or neither, but not both.

This command creates a counter named NAME.  In addition, unless the optional argument NUMBERED_LIKE is used, inside of the theorem-like environment the current \ref value will be that of \theNUMBERED_WITHIN (see \ref).

This declaration is global.  It is fragile (see \protect).

Arguments:

name
     The name of the environment.  It must not begin with a backslash (\).  It must not be the name of an existing environment; indeed, the command name \NAME must not already be defined as anything.

title
     The text printed at the beginning of the environment, before the number. For example, Theorem.

numbered_within
     Optional; the name of an already defined counter, usually a sectional unit such as chapter or section.  When the NUMBERED_WITHIN counter is reset then the NAME environment's counter will also be reset.

     If this optional argument is not used then the command \theNAME is set to \arabic{NAME}.

numbered_like
     Optional; the name of an already defined theorem-like environment. The new environment will be numbered in sequence with NUMBERED_LIKE.

Without any optional arguments the environments are numbered sequentially.  The example below has a declaration in the preamble that results in Definition 1 and Definition 2 in the output.

     \newtheorem{defn}{Definition}
     \begin{document}
     \section{...}
     \begin{defn}
       First def
     \end{defn}

     \section{...}
     \begin{defn}
       Second def
     \end{defn}

Because the next example specifies the optional argument NUMBERED_WITHIN to \newtheorem as section, the example, with the same document body, gives Definition 1.1 and Definition 2.1.

     \newtheorem{defn}{Definition}[section]
     \begin{document}
     \section{...}
     \begin{defn}
       First def
     \end{defn}

     \section{...}
     \begin{defn}
       Second def
     \end{defn}

In the next example there are two declarations in the preamble, the second of which calls for the new thm environment to use the same counter as defn.  It gives Definition 1.1, followed by Theorem 2.1 and Definition 2.2.

     \newtheorem{defn}{Definition}[section]
     \newtheorem{thm}[defn]{Theorem}
     \begin{document}
     \section{...}
     \begin{defn}
       First def
     \end{defn}

     \section{...}
     \begin{thm}
       First thm
     \end{thm}

     \begin{defn}
       Second def
     \end{defn}

\newfont: Define a new font (obsolete)
======================================

\newfont, now obsolete, defines a command that will switch fonts. Synopsis:

     \newfont{\CMD}{FONT DESCRIPTION}

This defines a control sequence \CMD that will change the current font.  LaTeX will look on your system for a file named FONTNAME.tfm.  The control sequence must must not already be defined.  It must begin with a backslash (\).

This command is obsolete.  It is a low-level command for setting up an individual font.  Today fonts are almost always defined in families (which allows you to, for example, associate a boldface with a roman) through the so-called ``New Font Selection Scheme'', either by using .fd files or through the use of an engine that can access system fonts such as XeLaTeX (see TeX engines).

But since it is part of LaTeX, here is an explanation: the FONT DESCRIPTION consists of a FONTNAME and an optional at clause; this can have the form either at DIMEN or scaled FACTOR, where a FACTOR of 1000 means no scaling.  For LaTeX's purposes, all this does is scale all the character and other font dimensions relative to the font's design size, which is a value defined in the .tfm file.

This example defines two equivalent fonts and typesets a few characters in each:

     \newfont{\testfontat}{cmb10 at 11pt}
     \newfont{\testfontscaled}{cmb10 scaled 1100}
     \testfontat abc
     \testfontscaled abc

\protect
========

All LaTeX commands are either fragile or robust.  A fragile command can break when it is used in the argument to certain other commands.  Commands that contain data that LaTeX writes to an auxiliary file and re-reads later are fragile.  This includes material that goes into a table of contents, list of figures, list of tables, etc.  Fragile commands also include line breaks, any command that has an optional argument, and many more. To prevent such commands from breaking, one solution is to preceded them with the command \protect.

For example, when LaTeX runs the \section{SECTION NAME} command it writes the SECTION NAME text to the .aux auxiliary file, moving it there for use elsewhere in the document such as in the table of contents.  Any argument that is internally expanded by LaTeX without typesetting it directly is referred to as a moving argument.  A command is fragile if it can expand during this process into invalid TeX code.  Some examples of moving arguments are those that appear in the \caption{...} command (see figure), in the \thanks{...} command (see \maketitle), and in @-expressions in the tabular and array environments (see tabular).

If you get strange errors from commands used in moving arguments, try preceding it with \protect.  Every fragile commands must be protected with their own \protect.

Although usually a \protect command doesn't hurt, length commands are robust and should not be preceded by a \protect command. Nor can a \protect command be used in the argument to \addtocounter or \setcounter command.

In this example the \caption command gives a mysterious error about an extra curly brace.  Fix the problem by preceding each \raisebox command with \protect.

     \begin{figure}
       ...
       \caption{Company headquarters of A\raisebox{1pt}{B}\raisebox{-1pt}{C}}
     \end{figure}

In the next example the \tableofcontents command gives an error because the \(..\) in the section title expands to illegal TeX in the .toc file.  You can solve this by changing \(..\) to \protect\(..\protect\).

     \begin{document}
     \tableofcontents
     ...
     \section{Einstein's \( e=mc^2 \)}
     ...

\ignorespaces & \ignorespacesafterend
=====================================

Synopsis:

     \ignorespaces

or

     \ignorespacesafterend

Both commands cause LaTeX to ignore spaces after the end of the command up until the first non-space character.  The first is a command from Plain TeX, and the second is LaTeX-specific.

The ignorespaces is often used when defining commands via \newcommand, or \newenvironment, or \def.  The example below illustrates.  It allows a user to show the points values for quiz questions in the margin but it is inconvenient because, as shown in the enumerate list, users must not put any space between the command and the question text.

     \newcommand{\points}[1]{\makebox[0pt]{\makebox[10em][l]{#1~pts}}
     \begin{enumerate}
       \item\points{10}no extra space output here
       \item\points{15} extra space output between the number and the word `extra'
     \end{enumerate}

The solution is to change to \newcommand{\points}[1]{\makebox[0pt]{\makebox[10em][l]{#1~pts}}\ignorespaces}.

A second example shows spaces being removed from the front of text.  The commands below allow a user to uniformly attach a title to names.  But, as given, if a title accidentally starts with a space then \fullname will reproduce that.

     \makeatletter
     \newcommand{\honorific}[1]{\def\@honorific{#1}} % remember title
     \newcommand{\fullname}[1]{\@honorific~#1}       % recall title; put before name
     \makeatother
     \begin{tabular}{|l|}
     \honorific{Mr/Ms}  \fullname{Jones} \\  % no extra space here
     \honorific{ Mr/Ms} \fullname{Jones}     % extra space before title
     \end{tabular}

To fix this, change to \newcommand{\fullname}[1]{\ignorespaces\@honorific~#1}.

The \ignorespaces is also often used in a \newenvironment at the end of the BEGIN clause, that is, as part of the second argument, as in \begin{newenvironment}{ENV NAME}{... \ignorespaces}{...}.

To strip spaces off the end of an environment use \ignorespacesafterend.  An example is that this will show a much larger vertical space between the first and second environments than between the second and third.

     \newenvironment{eq}{\begin{equation}}{\end{equation}}
     \begin{eq}
     e=mc^2
     \end{eq}
     \begin{equation}
     F=ma
     \end{equation}
     \begin{equation}
     E=IR
     \end{equation}

Putting a comment character % immediately after the \end{eq} will make the vertical space disappear, but that is inconvenient.  The solution is to change to \newenvironment{eq}{\begin{equation}}{\end{equation}\ignorespacesafterend}.

Counters
********

Everything LaTeX numbers for you has a counter associated with it. The name of the counter is often the same as the name of the environment or command associated with the number, except that the counter's name has no backslash \.  Thus, associated with the \chapter command is the chapter counter that keeps track of the chapter number.

Below is a list of the counters used in LaTeX's standard document classes to control numbering.

     part            paragraph       figure          enumi
     chapter         subparagraph    table           enumii
     section         page            footnote        enumiii
     subsection      equation        mpfootnote      enumiv
     subsubsection

The mpfootnote counter is used by the \footnote command inside of a minipage (see minipage).  The counters enumi through enumiv are used in the enumerate environment, for up to four levels of nesting (see enumerate).

New counters are created with \newcounter.  See \newcounter.

\alph \Alph \arabic \roman \Roman \fnsymbol: Printing counters
==============================================================

Print the value of a counter, in a specified style.  For instance, if the counter COUNTER has the value 1 then a \alph{COUNTER} in your source will result in a lower case letter a appearing in the output.

All of these commands take a single counter as an argument, for instance, \alph{enumi}.  Note that the counter name does not start with a backslash.

\alph{COUNTER}
     Print the value of COUNTER in lowercase letters: `a', `b', ...

\Alph{COUNTER}
     Print in uppercase letters: `A', `B', ...

\arabic{COUNTER}
     Print in Arabic numbers: `1', `2', ...

\roman{COUNTER}
     Print in lowercase roman numerals: `i', `ii', ...

\Roman{COUNTER}
     Print in uppercase roman numerals: `I', `II', ...

\fnsymbol{COUNTER}
     Prints the value of COUNTER in a specific sequence of nine symbols (conventionally used for labeling footnotes).  The value of COUNTER must be between 1 and 9, inclusive.

     Here are the symbols:

     Name  Command  Symbol,Equivalent Unicode symbol and/or numeric code point

     asterisk  \ast,*

     dagger  \dagger

     ddagger  \ddagger

     section-sign  \S

     paragraph-sign  \P

     double-vert  \parallel

     double-asterisk  \ast\ast,**

     double-dagger  \dagger\dagger

     double-ddagger  \ddagger\ddagger

\usecounter{COUNTER}
====================

Synopsis:

     \usecounter{COUNTER}

In the list environment, when used in the second argument, this command sets up COUNTER to number the list items.  It initializes COUNTER to zero, and arranges that when \item is called without its optional argument then COUNTER is incremented by \refstepcounter, making its value be the current ref value.  This command is fragile (see \protect).

Put in the preamble, this makes a new list environment enumerated with TESTCOUNTER:

     \newcounter{testcounter}
     \newenvironment{test}{%
       \begin{list}{}{%
         \usecounter{testcounter}
       }
     }{%
       \end{list}
     }

\value{COUNTER}
===============

Synopsis:

     \value{COUNTER}

This command expands to the value of COUNTER.  It is often used in \setcounter or \addtocounter, but \value can be used anywhere that LaTeX expects a number.  It must not be preceded by \protect (see \protect).

The \value command is not used for typesetting the value of the counter.  See \alph \Alph \arabic \roman \Roman \fnsymbol.

This example outputs Test counter is 6. Other counter is 5..

     \newcounter{test} \setcounter{test}{5}
     \newcounter{other} \setcounter{other}{\value{test}}
     \addtocounter{test}{1}

     Test counter is \arabic{test}.
     Other counter is \arabic{other}.

This example inserts \hspace{4\parindent}.

     \setcounter{myctr}{3} \addtocounter{myctr}{1}
     \hspace{\value{myctr}\parindent}

\setcounter{COUNTER}{VALUE}
===========================

Synopsis:

     \setcounter{COUNTER}{VALUE}

The \setcounter command globally sets the value of COUNTER to the VALUE argument.  Note that the counter name does not start with a backslash.

In this example the section value appears as V.

     \setcounter{section}{5}
     Here it is in Roman: \Roman{section}.

\addtocounter{COUNTER}{VALUE}
=============================

The \addtocounter command globally increments COUNTER by the amount specified by the VALUE argument, which may be negative.

In this example the section value appears as VII.

     \setcounter{section}{5}
     \addtocounter{section}{2}
     Here it is in Roman: \Roman{section}.

\refstepcounter{COUNTER}
========================

The \refstepcounter command works in the same way as \stepcounter (see \stepcounter): it globally increments the value of COUNTER by one and resets the value of any counter numbered within it.  (For the definition of ``counters numbered within'', see \newcounter.)

In addition, this command also defines the current \ref value to be the result of \thecounter.

While the counter value is set globally, the \ref value is set locally, i.e., inside the current group.

\stepcounter{COUNTER}
=====================

The \stepcounter command globally adds one to COUNTER and resets all counters numbered within it.  (For the definition of ``counters numbered within'', see \newcounter.)

\day \month \year: Predefined counters
======================================

LaTeX defines counters for the day of the month (\day, 1--31), month of the year (\month, 1--12), and year (\year, Common Era).  When TeX starts up, they are set to the current values on the system where TeX is running.  They are not updated as the job progresses.

The related command \today produces a string representing the current day (see \today).

Lengths
*******

A length is a measure of distance.  Many LaTeX commands take a length as an argument.

Lengths come in two types.  A rigid length (what Plain TeX calls a dimen) such as 10pt cannot contain a plus or minus component.  A rubber length (what Plain TeX calls a skip) can contain those, as with 1cm plus0.05cm minus0.01cm.  These give the ability to stretch or shrink; the length in the prior sentence could appear in the output as long as 1.05 cm or as short as 0.99 cm, depending on what TeX's typesetting algorithm finds optimum.

The plus or minus component of a rubber length can contain a fill component, as in 1in plus2fill.  This gives the length infinite stretchability or shrinkability, so that the length in the prior sentence can be set by TeX to any distance greater than or equal to 1 inch.  TeX actually provides three infinite glue components fil, fill, and filll, such that the later ones overcome the earlier ones, but only the middle value is ordinarily used.  See \hfill, see \vfill.

Multiplying an entire rubber length by a number turns it into a rigid length, so that after \setlength{\ylength}{1in plus 0.2in} and \setlength{\zlength}{3\ylength} then the value of \zlength is 3in.

Units of length
===============

TeX and LaTeX know about these units both inside and outside of math mode.

pt
     Point 1/72.27 inch.  The conversion to metric units, to two decimal places, is 1point = 2.85mm = 28.45cm.

pc
     Pica, 12 pt

in
     Inch,  72.27 pt

bp
     Big point, 1/72 inch.  This length is the definition of a point in PostScript and many desktop publishing systems.

cm
     Centimeter

mm
     Millimeter

dd
     Didot point, 1.07 pt

cc
     Cicero, 12 dd

sp
     Scaled point, 1/65536 pt

Two other lengths that are often used are values set by the designer of the font.  The x-height of the current font ex, traditionally the height of the lower case letter x, is often used for vertical lengths. Similarly em, traditionally the width of the capital letter M, is often used for horizontal lengths (there is also \enspace, which is 0.5em).  Use of these can help make a definition work better across font changes.  For example, a definition of the vertical space between list items given as \setlength{\itemsep}{1ex plus 0.05ex minus 0.01ex} is more likely to still be reasonable if the font is changed than a definition given in points.

In math mode, many definitions are expressed in terms of the math unit mu given by 1 em = 18 mu, where the em is taken from the current math symbols family.  See Spacing in math mode.

\setlength
==========

Synopsis:

     \setlength{\LEN}{AMOUNT}

The \setlength sets the value of length command \LEN to the VALUE argument which can be expressed in any units that LaTeX understands, i.e., inches (in), millimeters (mm), points (pt), big points (bp), etc.

\addtolength
============

Synopsis:

     \addtolength{\LEN}{AMOUNT}

The \addtolength command increments a length command \LEN by the amount specified in the AMOUNT argument, which may be negative.

\settodepth
===========

Synopsis:

     \settodepth{\LEN}{TEXT}

The \settodepth command sets the value of a length command \LEN equal to the depth of the TEXT argument.

\settoheight
============

Synopsis:

     \settoheight{\LEN}{text}

The \settoheight command sets the value of a length command \LEN equal to the height of the text argument.

\settowidth{\LEN}{TEXT}
=======================

Synopsis:

     \settowidth{\LEN}{TEXT}

The \settowidth command sets the value of the command \LEN to the width of the TEXT argument.

Predefined lengths
==================

\width

\height

\depth

\totalheight

These length parameters can be used in the arguments of the box-making commands (see Boxes).  They specify the natural width, etc., of the text in the box. \totalheight equals \height + \depth. To make a box with the text stretched to double the natural size, e.g., say

     \makebox[2\width]{Get a stretcher}

Making paragraphs
*****************

A paragraph is ended by one or more completely blank lines---lines not containing even a %.  A blank line should not appear where a new paragraph cannot be started, such as in math mode or in the argument of a sectioning command.

\indent
=======

\indent produces a horizontal space whose width equals to the \parindent length, the normal paragraph indentation.  It is used to add paragraph indentation where it would otherwise be suppressed.

The default value for \parindent is 1em in two-column mode, otherwise 15pt for 10pt documents, 17pt for 11pt, and 1.5em for 12pt.

\noindent
=========

When used at the beginning of the paragraph, this command suppresses any paragraph indentation, as in this example.

     ... end of the prior paragraph.

     \noindent This paragraph is not indented.

It has no effect when used in the middle of a paragraph.

To eliminate paragraph indentation in an entire document, put \setlength{\parindent}{0pt} in the preamble.

\parskip
========

\parskip is a rubber length defining extra vertical space added before each paragraph.  The default is 0pt plus1pt.

Marginal notes
==============

Synopsis:

     \marginpar[LEFT]{RIGHT}

The \marginpar command creates a note in the margin.  The first line of the note will have the same baseline as the line in the text where the \marginpar occurs.

When you only specify the mandatory argument RIGHT, the text will be placed

  * in the right margin for one-sided layout (option oneside, see Document class options);

  * in the outside margin for two-sided layout (option twoside, see Document class options);

  * in the nearest margin for two-column layout (option twocolumn, see Document class options).

The command \reversemarginpar places subsequent marginal notes in the opposite (inside) margin.  \normalmarginpar places them in the default position.

When you specify both arguments, LEFT is used for the left margin, and RIGHT is used for the right margin.

The first word will normally not be hyphenated; you can enable hyphenation there by beginning the node with \hspace{0pt}.

These parameters affect the formatting of the note:

\marginparpush
     Minimum vertical space between notes; default 7pt for 12pt documents, 5pt else.

\marginparsep
     Horizontal space between the main text and the note; default 11pt for 10pt documents, 10pt else.

\marginparwidth
     Width of the note itself; default for a one-sided 10pt document is 90pt, 83pt for 11pt, and 68pt for 12pt; 17pt more in each case for a two-sided document. In two column mode, the default is 48pt.

The standard LaTeX routine for marginal notes does not prevent notes from falling off the bottom of the page.

Math formulas
*************

There are three environments that put LaTeX in math mode:

math
     For formulas that appear right in the text.

displaymath
     For formulas that appear on their own line.

equation
     The same as the displaymath environment except that it adds an equation number in the right margin.

The math environment can be used in both paragraph and LR mode, but the displaymath and equation environments can be used only in paragraph mode.  The math and displaymath environments are used so often that they have the following short forms:

     \(...\)   instead of   \begin{math}...\end{math}
     \[...\]   instead of   \begin{displaymath}...\end{displaymath}

In fact, the math environment is so common that it has an even shorter form:

     $ ... $   instead of   \(...\)

The \boldmath command changes math letters and symbols to be in a bold font.  It is used outside of math mode.  Conversely, the \unboldmath command changes math glyphs to be in a normal font; it too is used outside of math mode.

The \displaystyle declaration forces the size and style of the formula to be that of displaymath, e.g., with limits above and below summations.  For example:

     $\displaystyle \sum_{n=0}^\infty x_n $

Subscripts & superscripts
=========================

In math mode, use the caret character ^ to make the EXP appear as a superscript: ^{EXP}. Similarly, in math mode, underscore _{EXP} makes a subscript out of EXP.

In this example the 0 and 1 appear as subscripts while the 2 is a superscript.

     \( (x_0+x_1)^2 \)

To have more than one character in EXP use curly braces as in e^{-2x}.

LaTeX handles superscripts on superscripts, and all of that stuff, in the natural way, so expressions such as e^{x^2} and x_{a_0} will look right.  It also does the right thing when something has both a subscript and a superscript.  In this example the 0 appears at the bottom of the integral sign while the 10 appears at the top.

     \int_0^{10} x^2 \,dx

You can put a superscript or subscript before a symbol with a construct such as {}_t K^2 in math mode (the initial {} prevents the prefixed subscript from being attached to any prior symbols in the expression).

Outside of math mode, a construct like A test$_\textnormal{subscript}$ will produce a subscript typeset in text mode, not math mode.  Note that there are packages specialized for writing Chemical formulas such as mhchem.

Math symbols
============

LaTeX provides almost any mathematical symbol you're likely to need. For example, if you include $\pi$ in your source, you will get the pi symbol.

Below is a list of commonly-available symbols.  It is by no means an exhaustive list.  Each symbol here is described with a short phrase, and its symbol class (which determines the spacing around it) is given in parenthesis.  Unless said otherwise, the commands for these symbols can be used only in math mode.

To redefine a command so that it can be used whatever the current mode, see \ensuremath.

\|
     Parallel (relation). Synonym: \parallel.

\aleph
     Aleph, transfinite cardinal (ordinary).

\alpha
     Lower case Greek letter alpha (ordinary).

\amalg
     Disjoint union (binary)

\angle
     Geometric angle (ordinary). Similar: less-than sign < and angle bracket \langle.

\approx
     Almost equal to (relation).

\ast
     Asterisk operator, convolution, six-pointed (binary). Synonym: *, which is often a superscript or subscript, as in the Kleene star. Similar: \star, which is five-pointed, and is sometimes used as a general binary operation, and sometimes reserved for cross-correlation.

\asymp
     Asymptotically equivalent (relation).

\backslash
     \ Backslash (ordinary).  Similar: set minus \setminus, and \textbackslash for backslash outside of math mode.

\beta
     Lower case Greek letter beta (ordinary).

\bigcap
     Variable-sized, or n-ary, intersection (operator). Similar: binary intersection \cap.

\bigcirc
     Circle, larger (binary).  Similar: function composition \circ.

\bigcup
     Variable-sized, or n-ary, union (operator). Similar: binary union \cup.

\bigodot
     Variable-sized, or n-ary, circled dot operator (operator).

\bigoplus
     Variable-sized, or n-ary, circled plus operator (operator).

\bigotimes
     Variable-sized, or n-ary, circled times operator (operator).

\bigtriangledown
     Variable-sized, or n-ary, open triangle pointing down (operator).

\bigtriangleup
     Variable-sized, or n-ary, open triangle pointing up (operator).

\bigsqcup
     Variable-sized, or n-ary, square union (operator).

\biguplus
     Variable-sized, or n-ary, union operator with a plus (operator).  (Note that the name has only one p.)

\bigvee
     Variable-sized, or n-ary, logical-and (operator).

\bigwedge
     Variable-sized, or n-ary, logical-or (operator).

\bot
     Up tack, bottom, least element of a partially ordered set, or a contradiction (ordinary).  See also \top.

\bowtie
     Natural join of two relations (relation).

\Box
     Modal operator for necessity; square open box (ordinary).  Not available in plain TeX. In LaTeX you need to load the amssymb package.

\bullet
     Bullet (binary).  Similar: multiplication dot \cdot.

\cap
     Intersection of two sets (binary).  Similar: variable-sized operator \bigcap.

\cdot
     Multiplication (binary).  Similar: Bullet dot \bullet.

\chi
     Lower case Greek chi (ordinary).

\circ
     Function composition, ring operator (binary).  Similar: variable-sized operator \bigcirc.

\clubsuit
     Club card suit (ordinary).

\complement
     Set complement, used as a superscript as in $S^\complement$ (ordinary).  Not available in plain TeX. In LaTeX you need to load the amssymb package. Also used: $S^{\mathsf{c}}$ or $\bar{S}$.

\cong
     Congruent (relation).

\coprod
     Coproduct (operator).

\cup
     Union of two sets (binary).  Similar: variable-sized operator \bigcup.

\dagger
     Dagger relation (binary).

\dashv
     Dash with vertical, reversed turnstile (relation).  Similar: turnstile \vdash.

\ddagger
     Double dagger relation (binary).

\Delta
     Greek upper case delta, used for increment (ordinary).

\delta
     Greek lower case delta (ordinary).

\Diamond
     Large diamond operator (ordinary).  Not available in plain TeX. In LaTeX you need to load the amssymb package.

\diamond
     Diamond operator, or diamond bullet (binary).  Similar: large diamond \Diamond, circle bullet \bullet.

\diamondsuit
     Diamond card suit (ordinary).

\div
     Division sign (binary).

\doteq
     Approaches the limit (relation).  Similar: geometrically equal to \Doteq.

\downarrow
     Down arrow, converges (relation).  Similar: double line down arrow \Downarrow.

\Downarrow
     Double line down arrow (relation).  Similar: single line down arrow \downarrow.

\ell
     Lowercase cursive letter l (ordinary).

\emptyset
     Empty set symbol (ordinary).  The variant form is \varnothing.

\epsilon
     Lower case lunate epsilon (ordinary). Similar to Greek text letter. More widely used in mathematics is the script small letter epsilon \varepsilon. Related: the set membership relation \in.

\equiv
     Equivalence (relation).

\eta
     Lower case Greek letter (ordinary).

\exists
     Existential quantifier (ordinary).

\flat
     Musical flat (ordinary).

\forall
     Universal quantifier (ordinary).

\frown
     Downward curving arc (ordinary).

\Gamma
     Upper case Greek letter (ordinary).

\gamma
     Lower case Greek letter (ordinary).

\ge
     Greater than or equal to (relation).  This is a synonym for \geq.

\geq
     Greater than or equal to (relation).  This is a synonym for \ge.

\gets
     Is assigned the value (relation). Synonym: \leftarrow.

\gg
     Much greater than (relation).  Similar: much less than \ll.

\hbar
     Planck constant over two pi (ordinary).

\heartsuit
     Heart card suit (ordinary).

\hookleftarrow
     Hooked left arrow (relation).

\hookrightarrow
     Hooked right arrow (relation).

\iff
     If and only if (relation).  It is \Longleftrightarrow with a \thickmuskip on either side.

\Im
     Imaginary part (ordinary).  See: real part \Re.

\in
     Set element (relation).  See also: lower case lunate epsilon \epsilon and small letter script epsilon \varepsilon.

\infty
     Infinity (ordinary).

\int
     Integral (operator).

\iota
     Lower case Greek letter (ordinary).

\Join
     Condensed bowtie symbol (relation).  Not available in Plain TeX.

\kappa
     Lower case Greek letter (ordinary).

\Lambda
     Upper case Greek letter (ordinary).

\lambda
     Lower case Greek letter (ordinary).

\land
     Logical and (binary).  This is a synonym for \wedge. See also logical or \lor.

\langle
     Left angle, or sequence, bracket (opening).  Similar: less-than <. Matches \rangle.

\lbrace
     Left curly brace (opening). Synonym: \{. Matches \rbrace.

\lbrack
     Left square bracket (opening). Synonym: [. Matches \rbrack.

\lceil
     Left ceiling bracket, like a square bracket but with the bottom shaved off (opening). Matches \rceil.

\le
     Less than or equal to (relation).  This is a synonym for \leq.

\leadsto
     Squiggly right arrow (relation).  Not available in plain TeX. In LaTeX you need to load the amssymb package. To get this symbol outside of math mode you can put \newcommand*{\Leadsto}{\ensuremath{\leadsto}} in the preamble and then use \Leadsto instead.

\Leftarrow
     Is implied by, double-line left arrow (relation).  Similar: single-line left arrow \leftarrow.

\leftarrow
     Single-line left arrow (relation). Synonym: \gets. Similar: double-line left arrow \Leftarrow.

\leftharpoondown
     Single-line left harpoon, barb under bar (relation).

\leftharpoonup
     Single-line left harpoon, barb over bar (relation).

\Leftrightarrow
     Bi-implication; double-line double-headed arrow (relation). Similar: single-line double headed arrow \leftrightarrow.

\leftrightarrow
     Single-line double-headed arrow (relation).  Similar: double-line double headed arrow \Leftrightarrow.

\leq
     Less than or equal to (relation).  This is a synonym for \le.

\lfloor
     Left floor bracket (opening). Matches: \floor.

\lhd
     Arrowhead, that is, triangle, pointing left (binary). Not available in plain TeX. In LaTeX you need to load the amssymb package. For the normal subgroup symbol you should load amssymb and use \vartriangleleft (which is a relation and so gives better spacing).

\ll
     Much less than (relation).  Similar: much greater than \gg.

\lnot
     Logical negation (ordinary). Synonym: \neg.

\longleftarrow
     Long single-line left arrow (relation).  Similar: long double-line left arrow \Longleftarrow.

\longleftrightarrow
     Long single-line double-headed arrow (relation).  Similar: long double-line double-headed arrow \Longleftrightarrow.

\longmapsto
     Long single-line left arrow starting with vertical bar (relation).  Similar: shorter version \mapsto.

\longrightarrow
     Long single-line right arrow (relation).  Similar: long double-line right arrow \Longrightarrow.

\lor
     Logical or (binary).  Synonym: wedge \wedge.

\mapsto
     Single-line left arrow starting with vertical bar (relation). Similar: longer version \longmapsto.

\mho
     Conductance, half-circle rotated capital omega (ordinary). Not available in plain TeX. In LaTeX you need to load the amssymb package.

\mid
     Single-line vertical bar (relation).  A typical use of \mid is for a set \{\, x \mid x\geq 5 \,\}.

     Similar: \vert and | produce the same single-line vertical bar symbol but without any spacing (they fall in class ordinary) and you should not use them as relations but instead only as ordinals, i.e., footnote symbols.  For absolute value, see the entry for \vert and for norm see the entry for \Vert.

\models
     Entails, or satisfies; double turnstile, short double dash (relation).  Similar: long double dash \vDash.

\mp
     Minus or plus (relation).

\mu
     Lower case Greek letter (ordinary).

\nabla
     Hamilton's del, or differential, operator (ordinary).

\natural
     Musical natural notation (ordinary).

\ne
     Not equal (relation). Synonym: \neq.

\nearrow
     North-east arrow (relation).

\neg
     Logical negation (ordinary). Synonym: \lnot. Sometimes instead used for negation: \sim.

\neq
     Not equal (relation). Synonym: \ne.

\ni
     Reflected membership epsilon; has the member (relation). Synonym: \owns. Similar: is a member of \in.

\not
     Long solidus, or slash, used to overstrike a following operator (relation).

     Many negated operators that don't require \not are available, particularly with the amssymb package. For example, \notin is probably typographically preferable to \not\in.

\notin
     Not an element of (relation).  Similar: not subset of \nsubseteq.

\nu
     Lower case Greek letter (ordinary).

\nwarrow
     North-west arrow (relation).

\odot
     Dot inside a circle (binary).  Similar: variable-sized operator \bigodot.

\oint
     Contour integral, integral with circle in the middle (operator).

\Omega
     Upper case Greek letter (ordinary).

\omega
     Lower case Greek letter (ordinary).

\ominus
     Minus sign, or dash, inside a circle (binary).

\oplus
     Plus sign inside a circle (binary).  Similar: variable-sized operator \bigoplus.

\oslash
     Solidus, or slash, inside a circle (binary).

\otimes
     Times sign, or cross, inside a circle (binary).  Similar: variable-sized operator \bigotimes.

\owns
     Reflected membership epsilon; has the member (relation). Synonym: \ni. Similar: is a member of \in.

\parallel
     Parallel (relation). Synonym: \|.

\partial
     Partial differential (ordinary).

\perp
     Perpendicular (relation).  Similar: \bot uses the same glyph but the spacing is different because it is in the class ordinary.

\phi
     Lower case Greek letter (ordinary).  The variant form is \varphi.

\Pi
     Upper case Greek letter (ordinary).

\pi
     Lower case Greek letter (ordinary).  The variant form is \varpi.

\pm
     Plus or minus (binary).

\prec
     Precedes (relation). Similar: less than <.

\preceq
     Precedes or equals (relation). Similar: less than or equals \leq.

\prime
     Prime, or minute in a time expression (ordinary). Typically used as a superscript: $f^\prime$; $f^\prime$ and $f'$ produce the same result.  An advantage of the second is that $f'''$ produces the desired symbol, that is, the same result as $f^{\prime\prime\prime}$, but uses rather less typing.  You can only use \prime in math mode.  Using the right single quote ' in text mode produces a different character (apostrophe).

\prod
     Product (operator).

\propto
     Is proportional to (relation)

\Psi
     Upper case Greek letter (ordinary).

\psi
     Lower case Greek letter (ordinary).

\rangle
     Right angle, or sequence, bracket (closing). Similar: greater than >.  Matches:\langle.

\rbrace
     Right curly brace (closing). Synonym: \}. Matches \lbrace.

\rbrack
     Right square bracket (closing). Synonym: ]. Matches \lbrack.

\rceil
     Right ceiling bracket (closing). Matches \lceil.

\Re
     Real part, real numbers, cursive capital R (ordinary). Related: double-line, or blackboard bold, R \mathbb{R}; to access this, load the amsfonts package.

\restriction
     Restriction of a function (relation). Synonym: \upharpoonright.  Not available in plain TeX. In LaTeX you need to load the amssymb package.

\revemptyset
     Reversed empty set symbol (ordinary).  Related: \varnothing. Not available in plain TeX. In LaTeX you need to load the stix package.

\rfloor
     Right floor bracket, a right square bracket with the top cut off (closing). Matches \lfloor.

\rhd
     Arrowhead, that is, triangle, pointing right (binary). Not available in plain TeX. In LaTeX you need to load the amssymb package. For the normal subgroup symbol you should instead load amssymb and use \vartriangleright (which is a relation and so gives better spacing).

\rho
     Lower case Greek letter (ordinary).  The variant form is \varrho.

\Rightarrow
     Implies, right-pointing double line arrow (relation). Similar: right single-line arrow \rightarrow.

\rightarrow
     Right-pointing single line arrow (relation). Synonym: \to. Similar: right double line arrow \Rightarrow.

\rightharpoondown
     Right-pointing harpoon with barb below the line (relation).

\rightharpoonup
     Right-pointing harpoon with barb above the line (relation).

\rightleftharpoons
     Right harpoon up above left harpoon down (relation).

\searrow
     Arrow pointing southeast (relation).

\setminus
     Set difference, reverse solidus or slash, like \ (binary). Similar: backslash \backslash and also \textbackslash outside of math mode.

\sharp
     Musical sharp (ordinary).

\Sigma
     Upper case Greek letter (ordinary).

\sigma
     Lower case Greek letter (ordinary). The variant form is \varsigma.

\sim
     Similar, in a relation (relation).

\simeq
     Similar or equal to, in a relation (relation).

\smallint
     Integral sign that does not change to a larger size in a display (operator).

\smile
     Upward curving arc, smile (ordinary).

\spadesuit
     Spade card suit (ordinary).

\sqcap
     Square intersection symbol (binary). Similar: intersection cap.

\sqcup
     Square union symbol (binary). Similar: union cup. Related: variable-sized operator \bigsqcup.

\sqsubset
     Square subset symbol (relation). Similar: subset \subset. Not available in plain TeX. In LaTeX you need to load the amssymb package.

\sqsubseteq
     Square subset or equal symbol (binary). Similar: subset or equal to \subseteq.

\sqsupset
     Square superset symbol (relation). Similar: superset \supset. Not available in plain TeX. In LaTeX you need to load the amssymb package.

\sqsupseteq
     Square superset or equal symbol (binary). Similar: superset or equal \supseteq.

\star
     Five-pointed star, sometimes used as a general binary operation but sometimes reserved for cross-correlation (binary). Similar: the synonyms asterisk * and \ast, which are six-pointed, and more often appear as a superscript or subscript, as with the Kleene star.

\subset
     Subset (occasionally, is implied by) (relation).

\subseteq
     Subset or equal to (relation).

\succ
     Comes after, succeeds (relation). Similar: is less than >.

\succeq
     Succeeds or is equal to (relation). Similar: less than or equal to \leq.

\sum
     Summation (operator). Similar: Greek capital sigma \Sigma.

\supset
     Superset (relation).

\supseteq
     Superset or equal to (relation).

\surd
     Radical symbol (ordinary).  The LaTeX command \sqrt{...} typesets the square root of the argument, with a bar that extends to cover the argument.

\swarrow
     Southwest-pointing  arrow (relation).

\tau
     Lower case Greek letter (ordinary).

\theta
     Lower case Greek letter (ordinary). The variant form is \vartheta.

\times
     Primary school multiplication sign (binary). See also \cdot.

\to
     Right-pointing single line arrow (relation). Synonym: \rightarrow.

\top
     Top, greatest element of a partially ordered set (ordinary). See also \bot.

\triangle
     Triangle (ordinary).

\triangleleft
     Not-filled triangle pointing left (binary). Similar: \lhd. For the normal subgroup symbol you should load amssymb and use \vartriangleleft (which is a relation and so gives better spacing).

\triangleright
     Not-filled triangle pointing right (binary). For the normal subgroup symbol you should instead load amssymb and use \vartriangleright (which is a relation and so gives better spacing).

\unlhd
     Left-pointing not-filled underlined arrowhead, that is, triangle, with a line under (binary). Not available in plain TeX. In LaTeX you need to load the amssymb package.  For the normal subgroup symbol load amssymb and use \vartrianglelefteq (which is a relation and so gives better spacing).

\unrhd
     Right-pointing not-filled underlined arrowhead, that is, triangle, with a line under (binary). Not available in plain TeX. In LaTeX you need to load the amssymb package.  For the normal subgroup symbol load amssymb and use \vartrianglerighteq (which is a relation and so gives better spacing).

\Uparrow
     Double-line upward-pointing arrow (relation). Similar: single-line up-pointing arrow \uparrow.

\uparrow
     Single-line upward-pointing arrow, diverges (relation). Similar: double-line up-pointing arrow \Uparrow.

\Updownarrow
     Double-line upward-and-downward-pointing arrow (relation). Similar: single-line upward-and-downward-pointing arrow \updownarrow.

\updownarrow
     Single-line upward-and-downward-pointing arrow (relation). Similar: double-line upward-and-downward-pointing arrow \Updownarrow.

\upharpoonright
     Up harpoon, with barb on right side (relation). Synonym: \restriction.  Not available in plain TeX. In LaTeX you need to load the amssymb package.

\uplus
     Multiset union, a union symbol with a plus symbol in the middle (binary). Similar: union \cup. Related: variable-sized operator \biguplus.

\Upsilon
     Upper case Greek letter (ordinary).

\upsilon
     Lower case Greek letter (ordinary).

\varepsilon
     Small letter script epsilon (ordinary).  This is more widely used in mathematics than the non-variant lunate epsilon form \epsilon. Related: set membership \in.

\vanothing
     Empty set symbol. Similar: \emptyset. Related: \revemptyset. Not available in plain TeX. In LaTeX you need to load the amssymb package.

\varphi
     Variant on the lower case Greek letter (ordinary). The non-variant form is \phi.

\varpi
     Variant on the lower case Greek letter (ordinary). The non-variant form is \pi.

\varrho
     Variant on the lower case Greek letter (ordinary). The non-variant form is \rho.

\varsigma
     Variant on the lower case Greek letter (ordinary).  The non-variant form is \sigma.

\vartheta
     Variant on the lower case Greek letter (ordinary).  The non-variant form is \theta.

\vdash
     Provable; turnstile, vertical and a dash (relation). Similar: turnstile rotated a half-circle \dashv.

\vee
     Logical or; a downwards v shape (binary). Related: logical and \wedge. Similar: variable-sized operator \bigvee.

\Vert
     Vertical double bar (ordinary). Similar: vertical single bar \vert.

     For a norm symbol, you can use the mathtools package and add \DeclarePairedDelimiter\norm{\lVert}{\rVert} to your preamble. This gives you three command variants for double-line vertical bars that are correctly horizontally spaced: if in the document body you write the starred version $\norm*{M^\perp}$ then the height of the vertical bars will match the height of the argument, whereas with \norm{M^\perp} the bars do not grow with the height of the argument but instead are the default height, and \norm[SIZE COMMAND]{M^\perp} also gives bars that do not grow but are set to the size given in the SIZE COMMAND, e.g., \Bigg.

\vert
     Single line vertical bar (ordinary). Similar: double-line vertical bar \Vert. For such that, as in the definition of a set, use \mid because it is a relation.

     For absolute value you can use the mathtools package and add \DeclarePairedDelimiter\abs{\lvert}{\rvert} to your preamble. This gives you three command variants for single-line vertical bars that are correctly horizontally spaced: if in the document body you write the starred version $\abs*{\frac{22}{7}}$ then the height of the vertical bars will match the height of the argument, whereas with \abs{\frac{22}{7}} the bars do not grow with the height of the argument but instead are the default height, and \abs[SIZE COMMAND]{\frac{22}{7}} also gives bars that do not grow but are set to the size given in the SIZE COMMAND, e.g., \Bigg.

\wedge
     Logical and (binary).  Synonym: \land.  See also logical or \vee. Similar: variable-sized operator \bigwedge.

\wp
     Weierstrass p (ordinary).

\wr
     Wreath product (binary).

\Xi
     Upper case Greek letter (ordinary).

\xi
     Lower case Greek letter (ordinary).

\zeta
     Lower case Greek letter (ordinary).

Math functions
==============

These commands produce roman function names in math mode with proper spacing.

\arccos
     \arccos

\arcsin
     \arcsin

\arctan
     \arctan

\arg
     \arg

\bmod
     Binary modulo operator (x \bmod y)

\cos
     \cos

\cosh
     \cosh

\cot
     \cot

\coth
     \coth

\csc
     \csc

\deg
     \deg

\det
     \det

\dim
     \dim

\exp
     \exp

\gcd
     \gcd

\hom
     \hom

\inf
     \inf

\ker
     \ker

\lg
     \lg

\lim
     \lim

\liminf
     \liminf

\limsup
     \limsup

\ln
     \ln

\log
     \log

\max
     \max

\min
     \min

\pmod
     parenthesized modulus, as in (\pmod 2^n - 1)

\Pr
     \Pr

\sec
     \sec

\sin
     \sin

\sinh
     \sinh

\sup
     \sup

\tan
     \tan

\tanh
     \tanh

Math accents
============

LaTeX provides a variety of commands for producing accented letters in math.  These are different from accents in normal text (see Accents).

\acute
     Math acute accent: \acutex.

\bar
     Math bar-over accent: \barx.

\breve
     Math breve accent: \brevex.

\check
     Math háček (check) accent: \checkx.

\ddot
     Math dieresis accent: \ddotx.

\dot
     Math dot accent: \dotx.

\grave
     Math grave accent: \gravex.

\hat
     Math hat (circumflex) accent: \hatx.

\imath
     Math dotless i.

\jmath
     Math dotless j.

\mathring
     Math ring accent: x̊.

\tilde
     Math tilde accent: \tildex.

\vec
     Math vector symbol: \vecx.

\widehat
     Math wide hat accent: \widehatx+y.

\widetilde
     Math wide tilde accent: \widetildex+y.

Spacing in math mode
====================

In a math environment, LaTeX ignores the spaces that you use in the source, and instead puts in the spacing according to the normal rules for mathematics texts.

Many math mode spacing definitions are expressed in terms of the math unit mu given by 1 em = 18 mu, where the em is taken from the current math symbols family (see Units of length). LaTeX provides the following commands for use in math mode:

\;
     Normally 5.0mu plus 5.0mu.  The longer name is \thickspace.  Math mode only.

\:
\>
     Normally 4.0mu plus 2.0mu minus 4.0mu.  The longer name is \medspace.  Math mode only.

\,
     Normally 3mu.  The longer name is \thinspace.  This can be used in both math mode and text mode. See \thinspace.

\!
     A negative thin space. Normally -3mu.  Math mode only.

\quad
     This is 18mu, that is, 1em. This is often used for space surrounding equations or expressions, for instance for the space between two equations inside a displaymath environment.  It is available in both text and math mode.

\qquad
     A length of 2 quads, that is, 36mu = 2em.  It is available in both text and math mode.

In this example a thinspace separates the function from the infinitesimal.

     \int_0^1 f(x)\,dx

Math miscellany
===============

\*
     A discretionary multiplication symbol, at which a line break is allowed. Without the break multiplication is implicitly indicated by a space, while in the case of a break a symbol is printed immediately before the break. So

          \documentclass{article}
          \begin{document}
          Now \(A_3 = 0\), hence the product of all terms \(A_1\)
          through \(A_4\), that is \(A_1\* A_2\* A_3 \* A_4\), is
          equal to zero.
          \end{document}

     will make that sort of output (the ellipsis [...] is here to show the line break at the same place as in a TeX output) :

          Now A_3 = 0, [...] A_1 through A_4, that is A_1 A_2 \times
          A_3 A_4, is equal to zero.

\cdots
     A horizontal ellipsis with the dots raised to the center of the line.

\ddots
     A diagonal ellipsis: \ddots.

\frac{NUM}{DEN}
     Produces the fraction NUM divided by DEN.

\left DELIM1 ... \right DELIM2
     The two delimiters need not match; . acts as a null delimiter, producing no output.  The delimiters are sized according to the math in between.  Example: \left( \sum_{i=1}^{10} a_i \right].

\mathdollar
     Dollar sign in math mode: $.

\mathellipsis
     Ellipsis (spaced for text) in math mode: ....

\mathparagraph
     Paragraph sign (pilcrow) in math mode:.

\mathsection
     Section sign in math mode.

\mathsterling
     Sterling sign in math mode: £.

\mathunderscore
     Underscore in math mode: _.

\overbrace{MATH}
     Generates a brace over MATH. For example, \overbrace{x+\cdots+x}^{k \;\textrm{times}}.

\overline{TEXT}
     Generates a horizontal line over TEX. For example, \overline{x+y}.

\sqrt[ROOT]{ARG}
     Produces the representation of the square root of ARG.  The optional argument ROOT determines what root to produce.  For example, the cube root of x+y would be typed as \sqrt[3]{x+y}.

\stackrel{TEXT}{RELATION}
     Puts TEXT above RELATION.  For example, \stackrel{f}{\longrightarrow}.

\underbrace{MATH}
     Generates MATH with a brace underneath. For example, \underbrace{x+y+z}_{>\,0}

\underline{TEXT}
     Causes TEXT, which may be either math mode or not, to be underlined.  The line is always below the text, taking account of descenders.

\vdots
     Produces a vertical ellipsis.

Modes
*****

When LaTeX is processing your input text, it is always in one of three modes:

  * Paragraph mode

  * Math mode

  * Left-to-right mode, called LR mode for short

Mode changes occur only when entering or leaving an environment, or when LaTeX is processing the argument of certain text-producing commands.

Paragraph mode is the most common; it's the one LaTeX is in when processing ordinary text.  In this mode, LaTeX breaks the input text into lines and breaks the lines into pages.

LaTeX is in math mode when it's generating a mathematical formula, either displayed math or within a line.

In LR mode, as in paragraph mode, LaTeX considers the output that it produces to be a string of words with spaces between them. However, unlike paragraph mode, LaTeX keeps going from left to right; it never starts a new line in LR mode.  Even if you put a hundred words into an \mbox, LaTeX would keep typesetting them from left to right inside a single box (and then most likely complain because the resulting box was too wide to fit on the line). LaTeX is in LR mode when it starts making a box with an \mbox command.  You can get it to enter a different mode inside the box---for example, you can make it enter math mode to put a formula in the box.

There are also several text-producing commands and environments for making a box that put LaTeX into paragraph mode.  The box made by one of these commands or environments will be called a parbox. When LaTeX is in paragraph mode while making a box, it is said to be in ``inner paragraph mode'' (no page breaks).  Its normal paragraph mode, which it starts out in, is called ``outer paragraph mode''.

\ensuremath
===========

Synopsis:

     \ensuremath{FORMULA}

The \ensuremath command ensures that FORMULA is typeset in math mode whatever the current mode in which the command is used.

For instance:

     \documentclass{report}
     \newcommand{\ab}{\ensuremath{(\delta, \varepsilon)}}
     \begin{document}
     Now, the \ab\ pair is equal to \(\ab = (\frac{1}{\pi}, 0)\), ...
     \end{document}

One can redefine commands that can be used only in math mode so that they ca be used in any mode like in the following example given for \leadsto:

     \documentclass{report}
     \usepackage{amssymb}
     \newcommand{\originalMeaningOfLeadsTo}{}
     \let\originalMeaningOfLeadsTo\leadsto
     \renewcommand\leadsto{\ensuremath{\originalMeaningOfLeadsTo}}
     \begin{document}
     All roads \leadsto\ Rome.
     \end{document}

Page styles
***********

The \documentclass command determines the size and position of the page's head and foot.  The page style determines what goes in them.

\maketitle
==========

The \maketitle command generates a title on a separate title page---except in the article class, where the title is placed at the top of the first page.  Information used to produce the title is obtained from the following declarations:

\author{NAME \and NAME2}
     The \author command declares the document author(s), where the argument is a list of authors separated by \and commands.  Use \\ to separate lines within a single author's entry---for example, to give the author's institution or address.

\date{TEXT}
     The \date command declares TEXT to be the document's date.  With no \date command, the current date (see \today) is used.

\thanks{TEXT}
     The \thanks command produces a \footnote to the title, usually used for credit acknowledgements.

\title{TEXT}
     The \title command declares TEXT to be the title of the document.  Use \\ to force a line break, as usual.

\pagenumbering
==============

Synopsis:

     \pagenumbering{STYLE}

Specifies the style of page numbers, according to STYLE; also resets the page number to 1.  The STYLE argument is one of the following:

arabic
     arabic numerals

roman
     lowercase Roman numerals

Roman
     uppercase Roman numerals

alph
     lowercase letters

Alph
     uppercase letters

\pagestyle
==========

Synopsis:

     \pagestyle{STYLE}

The \pagestyle command specifies how the headers and footers are typeset from the current page onwards.  Values for STYLE:

plain
     Just a plain page number.

empty
     Empty headers and footers, e.g., no page numbers.

headings
     Put running headers on each page.  The document style specifies what goes in the headers.

myheadings
     Custom headers, specified via the \markboth or the \markright commands.

Here are the descriptions of \markboth and \markright:

\markboth{LEFT}{RIGHT}
     Sets both the left and the right heading.  A ``left-hand heading'' (LEFT) is generated by the last \markboth command before the end of the page, while a ``right-hand heading'' (RIGHT) is generated by the first \markboth or \markright that comes on the page if there is one, otherwise by the last one before the page.

\markright{RIGHT}
     Sets the right heading, leaving the left heading unchanged.

\thispagestyle{STYLE}
=====================

The \thispagestyle command works in the same manner as the \pagestyle command (see previous section) except that it changes to STYLE for the current page only.

Spaces
******

LaTeX has many ways to produce white (or filled) space.

\hspace
=======

Synopsis:

     \hspace{LENGTH}
     \hspace*{LENGTH}

Add the horizontal space given by LENGTH.  The LENGTH is a rubber length, that is, it may contain a plus or minus component, in any unit that LaTeX understands (see Lengths).

This command can add both positive and negative space; adding negative space is like backspacing.

Normally when TeX breaks a paragraph into lines it discards white space (glues and kerns) that would come at the start of a line, so you get an inter-word space or a line break between words but not both. This command's starred version \hspace*{...} puts a non-discardable invisible item in front of the space, so the space appears in the output.

This example make a one-line paragraph that puts Name: an inch from the right margin.

     \noindent\makebox[\linewidth]{\hspace{\fill}Name:\hspace{1in}}

\hfill
======

Produce a rubber length which has no natural space but can stretch horizontally as far as needed (see Lengths).

The command \hfill is equivalent to \hspace{\fill}.  For space that does not disappear at line breaks use \hspace*{\fill} instead (see \hspace).

\spacefactor
============

Synopsis:

     \spacefactor=INTEGER

While LaTeX is making the page, to give the lines the best appearance it may stretch or shrink the gaps between words.  The \spacefactor command (from Plain TeX) allows you to change the LaTeX's default behavior.

After LaTeX places each character, or rule or other box, it sets a parameter called the space factor.  If the next thing in the input is a space then this parameter affects how much of a horizontal gap LaTeX will have it span.  (This gap is not a character; it is called interword glue.)  A larger space factor means that the glue gap can stretch more and shrink less.

Normally, the space factor is 1000; this value is in effect following most characters, and any non-character box or math formula.  But it is 3000 after a period, exclamation mark, or question mark, it is 2000 after a colon, 1500 after a semicolon, 1250 after a comma, and 0 after a right parenthesis or bracket, or closing double quote or single quote. Finally, it is 999 after a capital letter.

If the space factor F is 1000 then the glue gap will be the font's normal space value (for Computer Modern Roman 10 point this is 3.3333 points).  Otherwise, if the space factor F is greater than 2000 then TeX adds the font's extra space value (for Computer Modern Roman 10 point this is 1.11111 points), and then the font's normal stretch value is multiplied by f /1000 and the normal shrink value is multiplied by 1000/f (for Computer Modern Roman 10 point these are 1.66666 and 1.11111 points).  In short, compared to a normal space, such as the space following a word ending in a lowercase letter, inter-sentence spacing has a fixed extra space added and then the space can stretch 3 times as much and shrink 1/3 as much.

The rules for how TeX uses space factors are even more complex because they play two more roles.  In practice, there are two consequences.  First, if a period or other punctuation is followed by a close parenthesis or close double quote then its effect is still in place, that is, the following glue will have increased stretch and shrink.  Second, conversely, if punctuation comes after a capital letter then its effect is not in place so you get an ordinary space.  For how to adjust to this second case, for instance if an abbreviation does not end in a capital letter, see \(SPACE) and \@.

\(SPACE) and \@
---------------

old name

Here, \(SPACE) means a backslash followed by a space.  These commands mark a punctuation character, typically a period, as either ending a sentence or as ending an abbreviation.

By default, in justifying a line LaTeX adjusts the space after a sentence-ending period (or a question mark, exclamation point, comma, or colon) more than the space between words.  See \spacefactor. As described there, LaTeX assumes that the period ends a sentence unless it is preceded by a capital letter, in which case it takes that period for part of an abbreviation.  Note that if a sentence-ending period is immediately followed by a right parenthesis or bracket, or right single or double quote, then the space effect of that period follows through that parenthesis or quote.

So: if you have a period ending an abbreviation whose last letter is not a capital letter, and that abbreviation is not the last word in the sentence, then follow that period with a backslash-space (\ ) or a tie (~) or a \@.  Examples are Nat.\ Acad.\ Science, and Mr.~Bean, and (manure, etc.\@) for sale (note that in the last the \@ comes before the closing parenthesis).

In the opposite situation, if you have a capital letter followed by a period that does end the sentence, then put \@ before the period.  For example, book by the MAA\@. will have correct inter-sentence spacing after the period.

For another use of \(SPACE), see \(SPACE) after control sequence.

\frenchspacing
--------------

This declaration (from Plain TeX) causes LaTeX to treat inter-sentence spacing in the same way as interword spacing.

In justifying the text in a line, some typographic traditions, including English, prefer to adjust the space between sentences (or after other punctuation marks) more than the space between words.  Following this declaration, all spaces are instead treated equally.

Revert to the default behavior by declaring \nonfrenchspacing.

\normalsfcodes
--------------

Reset the LaTeX space factor values to the default.

\ after control sequence
========================

The \  command is often used after control sequences to keep them from gobbling the space that follows, as in \TeX\ is nice. And, under normal circumstances, \tab and \newline are equivalent to \ . For another use of \ , see also \(SPACE) and \@.

Some people prefer to use {} for the same purpose, as in \TeX{} is nice. This has the advantage that you can always write it the same way, namely \TeX{}, whether it is followed by a space or by a punctuation mark. Compare:

     \TeX\ is a nice system. \TeX, a nice system.

     \TeX{} is a nice system. \TeX{}, a nice system.

Some individual commands, notably those defined with the xspace, package do not follow the standard behavior.

\thinspace: Insert 1/6em
========================

\thinspace produces an unbreakable and unstretchable space that is 1/6 of an em.  This is the proper space to use between nested quotes, as in '''. Abuse, which is a thin space in Texinfo.

\/: Insert italic correction
============================

The \/ command produces an italic correction.  This is a small space defined by the font designer for a given character, to avoid the character colliding with whatever follows.  The italic f character typically has a large italic correction value.

If the following character is a period or comma, it's not necessary to insert an italic correction, since those punctuation symbols have a very small height.  However, with semicolons or colons, as well as normal letters, it can help. Compare f: f; (in the TeX output, the `f's are nicely separated) with f: f;.

When changing fonts with commands such as \textit{italic text} or {\itshape italic text}, LaTeX will automatically insert an italic correction if appropriate (see Font styles).

Despite the name, roman characters can also have an italic correction.  Compare pdfTeX (in the TeX output, there is a small space after the `f') with pdfTeX.

There is no concept of italic correction in math mode; spacing is done in a different way.

\hrulefill \dotfill
===================

Produce an infinite rubber length (see Lengths) filled with a horizontal rule (that is, a line) or with dots, instead of just white space.

When placed between blank lines this example creates a paragraph that is left and right justified, where the space in the middle is filled with evenly spaced dots.

     \noindent Jack Aubrey\dotfill Melbury Lodge

To make the rule or dots go to the line's end use \null at the start or end.

To change the rule's thickness, copy the definition and adjust it, as with \renewcommand{\hrulefill}{\leavevmode\leaders\hrule height 1pt\hfill\kern\z@}, which changes the default thickness of 0.4pt to 1pt.  Similarly, adjust the dot spacing as with \renewcommand{\dotfill}{\leavevmode\cleaders\hb@xt@ 1.00em{\hss .\hss }\hfill\kern\z@}, which changes the default length of 0.33em to 1.00em.

\addvspace
==========

\addvspace{LENGTH}

Add a vertical space of height LENGTH, which is a rubber length (see Lengths).  However, if vertical space has already been added to the same point in the output by a previous \addvspace command then this command will not add more space than what is needed to make the natural length of the total vertical space equal to LENGTH.

Use this command to adjust the vertical space above or below an environment that starts a new paragraph.  For instance, a Theorem environment is defined to begin and end with \addvspace{...} so that two consecutive Theorem's are separated by one vertical space, not two.

This command is fragile (see \protect).

The error Something's wrong--perhaps a missing \item means that you were not in vertical mode when you invoked this command; one way to change that is to precede this command with a \par command.

\bigskip \medskip \smallskip
============================

These commands produce a given amount of space, specified by the document class.

\bigskip
     The same as \vspace{\bigskipamount}, ordinarily about one line space, with stretch and shrink (the default for the book and article classes is 12pt plus 4pt minus 4pt).

\medskip
     The same as \vspace{\medskipamount}, ordinarily about half of a line space, with stretch and shrink (the default for the book and article classes is 6pt plus 2pt minus 2pt).

\smallskip
     The same as \vspace{\smallskipamount}, ordinarily about a quarter of a line space, with stretch and shrink (the default for the book and article classes is 3pt plus 1pt minus 1pt).

\vfill
======

End the current paragraph and insert a vertical rubber length (see Lengths) that is infinite, so it can stretch or shrink as far as needed.

It is often used in the same way as \vspace{\fill}, except that \vfill ends the current paragraph, whereas \vspace{\fill} adds the infinite vertical space below its line irrespective of the paragraph structure.  In both cases that space will disappear at a page boundary; to circumvent this see \vspace.

In this example the page is filled, so the top and bottom lines contain the text Lost Dog! and the third Lost Dog! is exactly halfway between them.

     \begin{document}
     Lost Dog!
     \vfill
     Lost Dog!
     \vfill
     Lost Dog!
     \end{document}

\vspace{LENGTH}
===============

Synopsis, one of these two:

     \vspace{LENGTH}
     \vspace*{LENGTH}

Add the vertical space LENGTH.  This can be negative or positive, and is a rubber length (see Lengths).

LaTeX removes the vertical space from \vspace at a page break, that is, at the top or bottom of a page.  The starred version \vspace*{...} causes the space to stay.

If \vspace is used in the middle of a paragraph (i.e., in horizontal mode), the space is inserted after the line with the \vspace command.  A new paragraph is not started.

In this example the two questions will be evenly spaced vertically on the page, with at least one inch of space below each.

     \begin{document}
     1) Who put the bomp in the bomp bah bomp bah bomp?
     \vspace{1in plus 1fill}

     2) Who put the ram in the rama lama ding dong?
     \vspace{1in plus 1fill}
     \end{document}

Boxes
*****

All the predefined length parameters (see Predefined lengths) can be used in the arguments of the box-making commands.

\mbox{TEXT}
===========

The \mbox command creates a box just wide enough to hold the text created by its argument.  The TEXT is not broken into lines, so it can be used to prevent hyphenation.

\fbox and \framebox
===================

Synopses:

     \fbox{TEXT}
     \framebox[WIDTH][POSITION]{TEXT}

The \fbox and \framebox commands are like \mbox, except that they put a frame around the outside of the box being created.

In addition, the \framebox command allows for explicit specification of the box width with the optional WIDTH argument (a dimension), and positioning with the optional POSITION argument.

Both commands produce a rule of thickness \fboxrule (default 0.4pt), and leave a space of \fboxsep (default 3pt) between the rule and the contents of the box.

See \framebox (picture), for the \framebox command in the picture environment.

lrbox
=====

Synopsis:

     \begin{lrbox}{\CMD}
       TEXT
     \end{lrbox}

This is the environment form of \sbox.

The TEXT inside the environment is saved in the box \CMD, which must have been declared with \newsavebox.

\makebox
========

Synopsis:

     \makebox[WIDTH][POSITION]{TEXT}

The \makebox command creates a box just wide enough to contain the TEXT specified.  The width of the box can be overridden by the optional WIDTH argument.  The position of the text within the box is determined by the optional POSITION argument, which may take the following values:

c
     Centered (default).

l
     Flush left.

r
     Flush right.

s
     Stretch (justify) across entire WIDTH; TEXT must contain stretchable space for this to work.

\makebox is also used within the picture environment see \makebox (picture).

\parbox
=======

Synopsis:

     \parbox[POSITION][HEIGHT][INNER-POS]{WIDTH}{TEXT}

The \parbox command produces a box whose contents are created in paragraph mode.  It should be used to make a box small pieces of text, with nothing fancy inside.  In particular, you shouldn't use any paragraph-making environments inside a \parbox argument.  For larger pieces of text, including ones containing a paragraph-making environment, you should use a minipage environment (see minipage).

\parbox has two mandatory arguments:

width
     the width of the parbox;

text
     the text that goes inside the parbox.

By default LaTeX will position vertically a parbox so its center lines up with the center of the surrounding text line.  When the optional POSITION argument is present and equal either to t or b, this allows you respectively to align either the top or bottom line in the parbox with the baseline of the surrounding text. You may also specify m for POSITION to get the default behaviour.

The optional HEIGHT argument overrides the natural height of the box.

The INNER-POS argument controls the placement of the text inside the box, as follows; if it is not specified, POSITION is used.

t
     text is placed at the top of the box.

c
     text is centered in the box.

b
     text is placed at the bottom of the box.

s
     stretch vertically; the text must contain vertically stretchable space for this to work.

\raisebox
=========

Synopsis:

     \raisebox{DISTANCE}[HEIGHT][DEPTH]{TEXT}

The \raisebox command raises or lowers TEXT.  The first mandatory argument specifies how high TEXT is to be raised (or lowered if it is a negative amount).  TEXT itself is processed in LR mode.

The optional arguments HEIGHT and DEPTH are dimensions.  If they are specified, LaTeX treats TEXT as extending a certain distance above the baseline (HEIGHT) or below (DEPTH), ignoring its natural height and depth.

\savebox
========

Synopsis:

     \savebox{\BOXCMD}[WIDTH][POS]{TEXT}

This command typeset TEXT in a box just as with \makebox (see \makebox), except that instead of printing the resulting box, it saves it in the box labeled \BOXCMD, which must have been declared with \newsavebox (see \newsavebox).

\sbox{\BOXCMD}{TEXT}
====================

Synopsis:

     \sbox{\BOXCMD}{TEXT}

\sbox types TEXT in a box just as with \mbox (see \mbox) except that instead of the resulting box being included in the normal output, it is saved in the box labeled \BOXCMD.  \BOXCMD must have been previously declared with \newsavebox (see \newsavebox).

\usebox{\BOXCMD}
================

Synopsis:

     \usebox{\BOXCMD}

\usebox produces the box most recently saved in the bin \BOXCMD by a \savebox command (see \savebox).

Color
*****

You can add color to text, rules, etc.  You can also have color in a box or on an entire page and write text on top of it.

Color support comes as an additional package.  So all the commands below will only work if your document preamble contains \usepackage{color}, that brings in the standard package.

Many other packages also supplement LaTeX's color abilities. Particularly worth mentioning is xcolor, which is widely used and significantly extends the capabilities described here, including adding HTML and Hsb color models.

Color package options
=====================

Synopsis (must be in the document preamble):

     \usepackage[COMMA-SEPARATED OPTION LIST]{color}

When you load the color package there are two kinds of available options.

The first specifies the printer driver.  LaTeX doesn't contain information about different output systems but instead depends on information stored in a file.  Normally you should not specify the driver option in the document, and instead rely on your system's default. One advantage of this is that it makes the document portable across systems.  For completeness we include a list of the drivers.  The currently relevant ones are: dvipdfmx, dvips, dvisvgm, luatex, pdftex, xetex.  The two xdvi and oztex are essentially aliases for dvips (and xdvi is monochrome).  Ones that should not be used for new systems are: dvipdf, dvipdfm, dviwin, dvipsone, emtex, pctexps, pctexwin, pctexhp, pctex32, truetex, tcidvi, vtex (and dviwindo is an alias for dvipsone).

The second kind of options, beyond the drivers, are below.

monochrome
     Disable the color commands, so that they do not generate errors but do not generate color either.

dvipsnames
     Make available a list of 68 color names that are often used, particularly in legacy documents.  These color names were originally provided by the dvips driver, giving the option name.

nodvipsnames
     Do not load that list of color names, saving LaTeX a tiny amount of memory space.

Color models
============

A color model is a way of representing colors.  LaTeX's capabilities depend on the printer driver.  However, the pdftex, xetex, and luatex printer drivers are today by far the most commonly used.  The models below work for those drivers.  All but one of these is also supported by essentially all other printer drivers used today.

Note that color combination can be additive or subtractive.  Additive mixes colors of light, so that for instance combining full intensities of red, green, and blue produces white.  Subtractive mixes pigments, such as with inks, so that combining full intensity of cyan, magenta, and yellow makes black.

cmyk
     A comma-separated list with four real numbers between 0 and 1, inclusive.  The first number is the intensity of cyan, the second is magenta, and the others are yellow and black.  A number value of 0 means minimal intensity, while a 1 is for full intensity.  This model is often used in color printing.  It is a subtractive model.

gray
     A single real number between 0 and 1, inclusive.  The colors are shades of grey.  The number 0 produces black while 1 gives white.

rgb
     A comma-separated list with three real numbers between 0 and 1, inclusive.  The first number is the intensity of the red component, the second is green, and the third the blue.  A number value of 0 means that none of that component is added in, while a 1 means full intensity. This is an additive model.

RGB
     (pdftex, xetex, luatex drivers) A comma-separated list with three integers between 0 and 255, inclusive.  This model is a convenience for using rgb since outside of LaTeX colors are often described in a red-green-blue model using numbers in this range. The values entered here are converted to the rgb model by dividing by 255.

named
     Colors are accessed by name, such as PrussianBlue.  The list of names depends on the driver, but all support the names black, blue, cyan, green, magenta, red, white, and yellow (See the dvipsnames option in Color package options).

Commands for color
==================

These are the commands available with the color package.

Define colors
-------------

Synopsis:

     \definecolor{NAME}{MODEL}{SPECIFICATION}

Give the name NAME to the color.  For example, after \definecolor{silver}{rgb}{0.75,0.75,0.74} you can use that color name with Hi ho, \textcolor{silver}{Silver}!.

This example gives the color a more abstract name, so it could change and not be misleading.

     \definecolor{logocolor}{RGB}{145,92,131}    % RGB needs pdflatex
     \newcommand{\logo}{\textcolor{logocolor}{Bob's Big Bagels}}

Often a document's colors are defined in the preamble, or in the class or style, rather than in the document body.

Colored text
------------

Synopses:

     \textcolor{NAME}{...}
     \textcolor[COLOR MODEL]{COLOR SPECIFICATION}{...}

or

     \color{NAME}
     \color[COLOR MODEL]{SPECIFICATION}

The affected text gets the color.  This line

     \textcolor{magenta}{My name is Ozymandias, king of kings:} Look on my works, ye Mighty, and despair!

causes the first half to be in magenta while the rest is in black.  You can use a color declared with \definecolor in exactly the same way that we just used the builtin color magenta.

     \definecolor{MidlifeCrisisRed}{rgb}{1.0,0.11,0.0}
     I'm thinking about getting a \textcolor{MidlifeCrisisRed}{sports car}.

The two \textcolor and \color differ in that the first is a command form, enclosing the text to be colored as an argument.  Often this form is more convenient, or at least more explicit.  The second form is a declaration, as in The moon is made of {\color{green} green} cheese, so it is in effect until the end of the current group or environment.  This is sometimes useful when writing macros or as below where it colors everything inside the center environment, including the vertical and horizontal lines.

     \begin{center} \color{blue}
       \begin{tabular}{l|r}
         UL &UR \\ \hline
         LL &LR
       \end{tabular}
     \end{center}

You can use color in equations.  A document might have \definecolor{highlightcolor}{RGB}{225,15,0} in the preamble, and then contain this equation.

     \begin{equation}
       \int_a^b \textcolor{highlightcolor}{f'(x)}\,dx=f(b)-f(a)
     \end{equation}

Typically the colors used in a document are declared in a class or style but sometimes you want a one-off.  Those are the second forms in the synopses.

     Colors of \textcolor[rgb]{0.33,0.14,0.47}{Purple} and {\color[rgb]{0.72,0.60,0.37} Gold} for the team

The format of COLOR SPECIFICATION  depends on the color model (see Color models).  For instance, while rgb takes three numbers, gray takes only one.

     The selection was \textcolor[gray]{0.5}{grayed out}.

Colors inside colors do not combine.  Thus

     \textcolor{green}{kind of \textcolor{blue}{blue}}

has a final word that is blue, not a combination of blue and green.

Colored boxes
-------------

Synopses:

     \colorbox{NAME}{...}
     \colorbox[MODEL NAME]{BOX BACKGROUND COLOR SPECIFICATION}{...}

or

     \fcolorbox{FRAME COLOR}{BOX BACKGROUND COLOR}{...}
     \fcolorbox[MODEL NAME]{FRAME COLOR SPECIFICATION}{BOX BACKGROUND COLOR SPECIFICATION}{...}

Make a box with the stated background color.  The \fcolorbox command puts a frame around the box.  For instance this

     Name:~\colorbox{cyan}{\makebox[5cm][l]{\strut}}

makes a cyan-colored box that is five centimeters long and gets its depth and height from the \strut (so the depth is -.3\baselineskip and the height is \baselineskip).  This puts white text on a blue background.

     \colorbox{blue}{\textcolor{white}{Welcome to the machine.}}

The \fcolorbox commands use the same parameters as \fbox (see \fbox and \framebox), \fboxrule and \fboxsep, to set the thickness of the rule and the boundary between the box interior and the surrounding rule.  LaTeX's defaults are 0.4pt and 3pt, respectively.

This example changes the thickness of the border to 0.8 points.  Note that it is surrounded by curly braces so that the change ends at the end of the second line.

     {\setlength{\fboxrule}{0.8pt}
     \fcolorbox{black}{red}{Under no circumstances turn this knob.}}

Colored pages
-------------

Synopses:

     \pagecolor{NAME}
     \pagecolor[COLOR MODEL]{COLOR SPECIFICATION}
     \nopagecolor

The first two set the background of the page, and all subsequent pages, to the color.  For an explanation of the specification in the second form see Colored text.  The third returns the background to normal, which is a transparent background.  (If that is not supported use \pagecolor{white}, although that will make a white background rather than the default transparent background.)

      ...
     \pagecolor{cyan}
      ...
     \nopagecolor

Graphics
********

You can use graphics such as PNG or PDF files in your LaTeX document. You need an additional package, which comes standard with LaTeX. This example is the short how-to.

     \include{graphicx}  % goes in the preamble
       ...
     \includegraphics[width=0.5\linewidth]{plot.pdf}

To use the commands described here your document preamble must contain either \usepackage{graphicx} or \usepackage{graphics}. Most of the time, graphicx is the better choice.

Graphics come in two main types, raster and vector.  LaTeX can use both.  In raster graphics the file contains an entry for each location in an array, describing what color it is.  An example is a photograph, in JPG format.  In vector graphics, the file contains a list of instructions such as draw a circle with this radius and that center.  An example is a line drawing produced by the Asymptote program, in PDF format.  Generally vector graphics are more useful because you can rescale their size without pixelation or other problems, and because they often have a smaller size.

There are systems particularly well-suited to make graphics for a LaTeX document.  For example, these allow you to use the same fonts as in your document.  LaTeX comes with a picture environment (see picture) that has simple capabilities.  Besides that, there are other ways to include the graphic-making commands in the document.  Two such systems are the PSTricks and TikZ packages.  There are also systems external to LaTeX, that generate a graphic that you include using the commands of this chapter.  Two that use a programming language are Asymptote and MetaPost.  One that uses a graphical interface is Xfig. Full description of these systems is outside the scope of this document; see their documentation.

Graphics package options
========================

Synopsis (must be in the document preamble):

     \usepackage[COMMA-SEPARATED OPTION LIST]{graphics}

or

     \usepackage[COMMA-SEPARATED OPTION LIST]{graphicx}

The graphicx package has a format for optional arguments to the \includegraphics command that is convenient (it is the key-value format), so it is the better choice for new documents.  When you load the graphics or graphicx package with \usepackage there are two kinds of available options.

The first is that LaTeX does not contain information about different output systems but instead depends on information stored in a printer driver file.  Normally you should not specify the driver option in the document, and instead rely on your system's default. One advantage of this is that it makes the document portable across systems.

For completeness here is a list of the drivers.  The currently relevant ones are: dvipdfmx, dvips, dvisvgm, luatex, pdftex, xetex.  The two xdvi and oztex are essentially aliases for dvips (and xdvi is monochrome). Ones that should not be used for new systems are: dvipdf, dvipdfm, dviwin, dvipsone, emtex, pctexps, pctexwin, pctexhp, pctex32, truetex, tcidvi, vtex (and dviwindo is an alias for dvipsone).  These are stored in files with a .def extension, such as pdftex.def.

The second kind of options are below.

demo
     Instead of an image file, LaTeX puts in a 150 pt by 100 pt rectangle (unless another size is specified in the \includegraphics command).

draft
     For each graphic file, it is not shown but instead the file name is printed in a box of the correct size.  In order to determine the size, the file must be present.

final
     (Default) Override any previous draft option, so that the document shows the contents of the graphic files.

hiderotate
     Do not show rotated text.  (This allows for the possibility that a previewer does not have the capability to rotate text.)

hidescale
     Do not show scaled text.  (This allows for the possibility that a previewer does not have the capability to scale.)

hiresbb
     In a PS or EPS file the graphic size may be specified in two ways.  The %%BoundingBox lines describe the graphic size using integer multiples of a PostScript point, that is, integer multiples of 1/72 inch.  A later addition to the PostScript language allows decimal multiples, such as 1.23, in %%HiResBoundingBox lines.  This option has LaTeX to read the size from the latter.

Graphics package configuration
==============================

These commands configure the way LaTeX searches the file system for the graphic.

The behavior of file system search code is necessarily platform dependent.  In this document we cover Linux, Macintosh, and Windows, as those systems are typically configured.  For other situations consult the documentation in grfguide.pdf, or the LaTeX source, or your TeX distribution's documentation.

\graphicspath
-------------

Synopsis:

     \graphicspath{LIST OF DIR NAMES INSIDE CURLY BRACKETS}

Declare a list of directories to search for graphics files.  This allows you to later say something like \includegraphics{lion.png} instead of having to give its path.

LaTeX always looks for graphic files first in the current directory. The declaration below tells the system to then look in the subdirectory pix, and then ../pix.

     \usepackage{graphicx}   % or graphics; put in preamble
       ...
     \graphicspath{ {pix/} {../pix/} }

The \graphicspath declaration is optional.  If you don't include it then LaTeX's default is to search all of the places that it usually looks for a file (it uses LaTeX's \input@path).  In particular, in this case one of the places it looks is the current directory.

Enclose each directory name in curly braces; for example, above it says {pix}.  Do this even if there is only one directory. Each directory name must end in a forward slash, /.  This is true even on Windows, where good practice is to use forward slashes for all the directory separators since it makes the document portable to other platforms.  If you have spaces in your directory name then use double quotes, as with {"my docs/"}. Getting one of these rules wrong will cause LaTeX to report Error: File `FILENAME' not found.

Basically, the algorithm is that with this example, after looking in the current directory,

     \graphicspath{ {pix/} {../pix/} }
     ...
     \usepackage{lion.png}

for each of the listed directories, LaTeX concatenates it with the file name and searches for the result, checking for pix/lion.png and then ../pix/lion.png.  This algorithm means that the \graphicspath command does not recursively search subdirectories: if you issue \graphicspath{{a/}} and the graphic is in a/b/lion.png then LaTeX will not find it.  It also means that you can use absolute paths such as \graphicspath{{/home/jim/logos/}} or \graphicspath{{C:/Users/Albert/Pictures/}}.  However, using these means that the document is not portable.  (You could preserve portability by adjusting your TeX system settings configuration file parameter TEXINPUTS; see the documentation of your system.)

You can use \graphicspath in the preamble or in the document body.  You can use it more than once.  For debugging, show its value with \makeatletter\typeout{\Ginput@path}\makeatother.

The directories are taken with respect to the base file.  That is, suppose that you are working on a document based on book/book.tex and it contains \include{chapters/chap1}.  If in chap1.tex you put \graphicspath{{plots/}} then LaTeX will not search for graphics in book/chapters/plots, but instead in book/plots.

\DeclareGraphicsExtensions
--------------------------

Synopses:

     \DeclareGraphicsExtensions{COMMA-SEPARATED LIST OF FILE EXTENSIONS}

Declare the filename extensions to try.  This allows you to specify the order in which to choose graphic formats when you include graphic files by giving the filename without the extension, as in \includegraphics{functionplot}.

In this example, LaTeX will find files in the PNG format before PDF files.

     \DeclareGraphicsExtensions{.png,PNG,.pdf,.PDF}
       ...
     \includegraphics{lion}   % will find lion.png before lion.pdf

Because the file name lion does not have a period, LaTeX uses the extension list.  For each directory in the graphics path (see \graphicspath), LaTeX will try the extensions in the order given.  If it does not find such a file after trying all the directories and extensions then it reports ! LaTeX Error: File `lion' not found.  Note that you must include the periods at the start of the extensions.

Because Linux and Macintosh filenames are case sensitive, the list of file extensions is case sensitive on those platforms.  The Windows platform is not case sensitive.

You are not required to include \DeclareGraphicsExtensions in your document; the printer driver has a sensible default.  For example, the most recent pdftex.def has the extension list .png,.pdf,.jpg,.mps,.jpeg,.jbig2,.jb2,.PNG,.PDF,.JPG,.JPEG,.JBIG2,.JB2.

You can use this command in the preamble or in the document body.  You can use it more than once.  For debugging, show its value with \makeatletter\typeout{\Gin@extensions}\makeatother.

\DeclareGraphicsRule
--------------------

Synopsis:

     \DeclareGraphicsRule{EXTENSION}{TYPE}{SIZE-FILE EXTENSION}{COMMAND}

Declare how to handle graphic files whose names end in EXTENSION.

This example declares that all files with names have the form filename-without-dot.mps will be treated as output from MetaPost, meaning that the printer driver will use its MetaPost-handling code to input the file.

     \DeclareGraphicsRule{.mps}{mps}{.mps}{}

This

     \DeclareGraphicsRule{*}{mps}{*}{}

tells LaTeX that it should handle as MetaPost output any file with an extension not covered by another rule, so it covers filename.1, filename.2, etc.

This describes the four arguments.

extension
     The file extension to which this rule applies. The extension is anything after and including the first dot in the filename.  Use the Kleene star, *, to denote the default behaviour for all undeclared extensions.

type
     The type of file involved.  This type is a string that must be defined in the printer driver. For instance, files with extensions .ps, .eps, or .ps.gz may all be classed as type eps. All files of the same type will be input with the same internal command by the printer driver. For example, the file types that pdftex recognizes are: jpg, jbig2, mps, pdf, png, tif.

size-file extension
     The extension of the file to be read to determine the size of the graphic, if there is such a file. It may be the same as EXTENSION but it may be different.

     As an example, consider a PostScript graphic.  To make it smaller, it might be compressed into a .ps.gz file.  Compressed files are not easily read by LaTeX so you can put the bounding box information in a separate file. If SIZE-FILE EXTENSION is empty then you must specify size information in the arguments of \includegraphics.

     If the driver file has a procedure for reading size files for type then that will be used, otherwise it will use the procedure for reading .eps files.  (Thus you may specify the size of bitmap files in a file with a PostScript style %%BoundingBox line if no other format is available.)

command
     A command that will be applied to the file. This is very often left blank. This command must start with a single backward quote.  Thus, \DeclareGraphicsRule{.eps.gz}{eps}{.eps.bb}{`gunzip -c #1} specifies that any file with the extension .eps.gz should be treated as an eps file, with the the BoundingBox information stored in the file with extension .eps.bb, and that the command gunzip -c will run on your platform to decompresses the file.

     Such a command is specific to your platform.  In addition, your TeX system must allow you to run external commands; as a security measure modern systems restrict running commands unless you explicitly allow it. See the documentation for your TeX distribution.

Commands for graphics
=====================

These are the commands available with the graphics and graphicx packages.

\includegraphics
----------------

Synopses for graphics package:

     \includegraphics{FILENAME}
     \includegraphics[URX,URY]{FILENAME}
     \includegraphics[LLX,LLY][URX,URY]{FILENAME}
     \includegraphics*{FILENAME}
     \includegraphics*[URX,URY]{FILENAME}
     \includegraphics*[LLX,LLY][URX,URY]{FILENAME}

Synopses for graphicx package:

     \includegraphics{FILENAME}
     \includegraphics[KEY-VALUE LIST]{FILENAME}
     \includegraphics*{FILENAME}
     \includegraphics*[KEY-VALUE LIST]{FILENAME}

Include a graphics file.  The starred form \includegraphics* will clip the graphic to the size specified, while for the unstarred form any part of the graphic that is outside the box of the specified size will over-print the surrounding area.

This

     \usepackage{graphicx}  % in preamble
       ...
     \begin{center}
       \includegraphics{plot.pdf}
     \end{center}

will incorporate into the document the graphic in plot.pdf, centered and at its nominal size.  You can also give a path to the file, as with \includegraphics{graphics/plot.pdf}.  To specify a list of locations to search for the file, see \graphicspath.

If your filename includes spaces then put it in double quotes, as with \includegraphics{"sister picture.jpg"}.

The \includegraphics{FILENAME} command decides on the type of graphic by splitting FILENAME on the first dot.  You can use FILENAME with no dot, as in \includegraphics{turing} and then LaTeX tries a sequence of extensions such as .png and .pdf until it finds a file with that extension (see \DeclareGraphicsExtensions).

If your file name contains dots before the extension then you can hide them with curly braces, as in \includegraphics{{plot.2018.03.12.a}.pdf}.  Or, if you use the graphicx package then you can use the options type and ext; see below.  This and other filename issues are also handled with the package grffile.

This example puts a graphic in a figure environment so LaTeX can move it to the next page if fitting it on the current page is awkward (see figure).

     \begin{figure}
       \centering
       \includegraphics[width=3cm]{lungxray.jpg}
       \caption{The evidence is overwhelming: don't smoke.}  \label{fig:xray}
     \end{figure}

This places a graphic that will not float, so it is sure to appear at this point in the document even if makes LaTeX stretch the text or resort to blank areas on the page.  It will be centered and will have a caption.

     \usepackage{caption}  % in preamble
       ...
     \begin{center}
       \includegraphics{pix/nix.png}
       \captionof{figure}{The spirit of the night} \label{pix:nix}  % if you want a caption
     \end{center}

This example puts a box with a graphic side by side with one having text, with the two vertically centered.

     \newcommand*{\vcenteredhbox}[1]{\begingroup
                                     \setbox0=\hbox{#1}\parbox{\wd0}{\box0}\endgroup}
       ...
     \begin{center}
       \vcenteredhbox{\includegraphics[width=0.4\textwidth]{plot}}
       \hspace{1em}
       \vcenteredhbox{\begin{minipage}{0.4\textwidth}
                        \begin{displaymath}
                          f(x)=x\cdot \sin (1/x)
                        \end{displaymath}
                      \end{minipage}}
     \end{center}

If you use the graphics package then the only options involve the size of the graphic (but see \rotatebox and \scalebox). When one optional argument is present then it is [URX,URY] and it gives the coordinates of the top right corner of the image, as a pair of TeX dimensions (see Units of length).  If the units are omitted they default to bp.  In this case, the lower left corner of the image is assumed to be at (0,0). If two optional arguments are present then the leading one is [LLX,LLY], specifying the coordinates of the image's lower left.  Thus, \includegraphics[1in,0.618in]{...} calls for the graphic to be placed so it is 1 inch wide and 0.618 inches tall and so its origin is at (0,0).

The graphicx package gives you many more options.  Specify them in a key-value form, as here.

     \begin{center}
       \includegraphics[width=1in,angle=90]{lion}
       \hspace{2em}
       \includegraphics[angle=90,width=1in]{lion}
     \end{center}

The options are read left-to-right. So the first graphic above is made one inch wide and then rotated, while the second is rotated and then made one inch wide.  Thus, unless the graphic is perfectly square, the two will end with different widths and heights.

There are many options.  The primary ones are listed first.

Note that a graphic is placed by LaTeX into a box, which is traditionally referred to as its bounding box (distinct from the PostScript BoundingBox described below).  The graphic's printed area may go beyond this box, or sit inside this box, but when LaTeX makes up a page it puts together boxes and this is the box allocated for the graphic.

width
     The graphic will be shown so its bounding box is this width.  An example is \includegraphics[width=1in]{plot}.  You can use the standard TeX dimensions (see Units of length) and also convenient is \linewidth, or in a two-column document, \columnwidth (see Page layout parameters).  An example is that by using the calc package you can make the graphic be 1 cm narrow than the width of the text with \includegraphics[width=\linewidth-1.0cm]{hefferon.jpg}.

height
     The graphic will be shown so its bounding box is this height.  You can use the standard TeX dimensions (see Units of length), and also convenient are \pageheight and \textheight (see Page layout parameters).  For instance, \includegraphics[height=0.25\textheight]{godel} will make the graphic be a quarter of the height of the text area.

totalheight
     The graphic will be shown so its bounding box has this height plus depth.  This differs from the height if the graphic was rotated. For instance, if it has been rotated by -90 then it will have zero height but a large depth.

keepaspectratio
     If set to true, or just specified as with \includegraphics[...,keepaspectratio,...]{...} and you give as options both width and height (or totalheight), then LaTeX will make the graphic is as large as possible without distortion. That is, LaTeX will ensure that neither is the graphic wider than width nor taller than height (or totalheight).

scale
     Factor by which to scale the graphic.  Specifying \includegraphics[scale=2.0]{...} makes the graphic twice its nominal size.  This number may be any value; a number between 1 and 0 will shrink the graphic and a negative number will reflect it.

angle
     Rotate the picture.  The angle is taken in degrees and counterclockwise. The graphic is rotated about its origin; see that option.  For a complete description of how rotated material is typeset, see \rotatebox.

origin
     The point of the graphic about which the rotation happens.  Possible values are any string containing one or two of: l for left, r for right, b for bottom, c for center, t for top, and B for baseline.  Thus, \includegraphics[angle=180,origin=c]{moon} will turn the picture upside down from the center, while \includegraphics[angle=180,origin=lB]{LeBateau} will turn its picture upside down about its left baseline.  (The character c gives the horizontal center in bc or tc, but gives the vertical center in lc or rc.)  The default is lB.

     To rotate about an arbitrary point, see \rotatebox.

These are lesser-used options.

viewport
     Pick out a subregion of the graphic to show.  Takes four arguments, separated by spaces and given in TeX dimensions, as with \includegraphics[.., viewport=0in 0in 1in 0.618in]{...}.  The dimensions default to big points, bp.  They are taken relative to the origin specified by the bounding box.  See also the trim option.

trim
     Gives parts of the graphic to not show.  Takes four arguments, separated by spaces, that are given in TeX dimensions, as with \includegraphics[.., trim= 0in 0.1in 0.2in 0.3in, ...]{...}. These give the amounts of the graphic not to show, that is, LaTeX will crop the picture by 0 inches on the left, 0.1 inches on the bottom, 0.2 inches on the right, and 0.3 inches on the top.  See also the viewport option.

clip
     If set to true, or just specified as with \includegraphics[...,clip,...]{...}, then the graphic is cropped to the bounding box.  You can get this effect by instead using the starred form of the command, as \includegraphics*[...]{...}.

page
     Give the page number of a multi-page PDF file.  The default is page=1.

pagebox
     Specifies which bounding box to use for PDF files from among mediabox, cropbox, bleedbox, trimbox, or artbox.  PDF files do not have the BoundingBox that PostScript files have, but may specify up to four predefined rectangles. The MediaBox gives the boundaries of the physical medium. The CropBox is the region to which the contents of the page are to be clipped when displayed.  The BleedBox is the region to which the contents of the page should be clipped in production. The TrimBox is the intended dimensions of the finished page.  The ArtBox is the extent of the page's meaningful content.  The driver will set the image size based on CropBox if present, otherwise it will not use one of the others, with a driver-defined order of preference.  MediaBox is always present.

interpolate
     Enable or disable interpolation of raster images by the viewer.  Can be set with interpolate=true or just specified as with \includegraphics[...,interpolate,...]{...}.

quiet
     Do not write information to the log.  You can set it with quiet=true or just specified it with \includegraphics[...,quite,...]{...},

draft
     If you set it with draft=true or just specified it with \includegraphics[...,draft,...]{...}, then the graphic will not appear in the document, possibly saving color printer ink.  Instead, LaTeX will put an empty box of the correct size with the filename printed in it.

These options address the bounding box for Encapsulated PostScript graphic files, which have a size specified with a line %%BoundingBox that appears in the file.  It has four values, giving the lower x coordinate, lower y coordinate, upper x coordinate, and upper y coordinate.  The units are PostScript points, equivalent to TeX's big points, 1/72 inch. For example, if an .eps file has the line %%BoundingBox 10 20 40 80 then its natural size is 30/72 inch wide by 60/72 inch tall.

bb
     Specify the bounding box of the displayed region.  The argument is four dimensions separated by spaces, as with \includegraphics[.., bb= 0in 0in 1in 0.618in]{...}.  Usually \includegraphics reads the BoundingBox numbers from the EPS file automatically, so this option is only useful if the bounding box is missing from that file or if you want to change it.

bbllx, bblly, bburx, bbury
     Set the bounding box.  These four are obsolete, but are retained for compatibility with old packages.

natwidth, natheight
     An alternative for bb.  Setting \includegraphics[...,natwidth=1in,natheight=0.618in,...]{...} is the same as setting bb=0 0 1in 0.618in.

hiresbb
     If set to true, or just specified as with \includegraphics[...,hiresbb,...]{...}, then LaTeX will look for %%HiResBoundingBox lines instead of %%BoundingBox lines.  (The BoundingBox lines use only natural numbers while the HiResBoundingBox lines use decimals; both use units equivalent to TeX's big points, 1/72 inch.) To override a prior setting of true, you can set it to false.

These following options allow a user to override LaTeX's method of choosing the graphic type based on the filename extension.  An example is that \includegraphics[type=png,ext=.xxx,read=.xxx]{lion} will read the file lion.xxx as though it were lion.png. For more on these, see \DeclareGraphicsRule.

type
     Specify the graphics type.

ext
     Specify the graphics extension. Only use this in conjunction with the option type.

read
     Specify the file extension of the read file. Only use this in conjunction with the option type.

command
     Specify a command to be applied to this file. Only use this in conjunction with the option type.

\rotatebox
----------

Synopsis for graphics package:

     \rotatebox{ANGLE}{MATERIAL}

Synopses for graphicx package:

     \rotatebox{ANGLE}{MATERIAL}
     \rotatebox[KEY-VALUE LIST]{ANGLE}{MATERIAL}

Put MATERIAL in a box and rotate it ANGLE degrees counterclockwise.

This example rotates the table column heads forty five degrees.

     \begin{tabular}{ll}
       \rotatebox{45}{Character} &\rotatebox{45}{NATO phonetic}   \\
       A                         &AL-FAH  \\
       B                         &BRAH-VOH
     \end{tabular}

The MATERIAL can be anything that goes in a box, including a graphic.

       \rotatebox[origin=c]{45}{\includegraphics[width=1in]{lion}}

To place the rotated material, the first step is that LaTeX sets MATERIAL in a box, with a reference point on the left baseline. The second step is the rotation, by default about the reference point. The third step is that LaTeX computes a box to bound the rotated material.  Fourth, LaTeX moves this box horizontally so that the left edge of this new bounding box coincides with the left edge of the box from the first step (they need not coincide vertically).  This new bounding box, in its new position, is what LaTeX uses as the box when typesetting this material.

If you use the graphics package then the rotation is about the reference point of the box.  If you use the graphicx package then then these are the options that can go in the KEY-VALUE LIST, but note that you can get the same effect without needing this package, except for the x and y options (see \includegraphics).

origin
     The point of the MATERIAL's box about which the rotation happens. Possible values are any string containing one or two of: l for left, r for right, b for bottom, c for center, t for top, and B for baseline.  Thus, \includegraphics[angle=180,origin=c]{moon} will turn the picture upside down from the center, while \includegraphics[angle=180,origin=lB]{LeBateau} will turn its picture upside down about its left baseline.  (The character c gives the horizontal center in bc or tc but gives the vertical center in lc or rc.)  The default is lB.

x, y
     Specify an arbitrary point of rotation with \rotatebox[x=TEX DIMENSION,y=TEX DIMENSION]{...} (see Units of length).  These give the offset from the box's reference point.

units
     This key allows you to change the default of degrees counterclockwise. Setting units=-360 changes the direction to degrees clockwise and setting units=6.283185 changes to radians counterclockwise.

\scalebox
---------

Synopses:

     \scalebox{HORIZONTAL FACTOR}{MATERIAL}
     \scalebox{HORIZONTAL FACTOR}[VERTICAL FACTOR]{MATERIAL}
     \reflectbox{MATERIAL}

Scale the MATERIAL.

This example halves the size, both horizontally and vertically, of the first text and doubles the size of the second.

     \scalebox{0.5}{DRINK ME} and \scalebox{2.0}{Eat Me}

If you do not specify the optional VERTICAL FACTOR then it defaults to the same value as the HORIZONTAL FACTOR.

You can use this command to resize a graphic, as with \scalebox{0.5}{\includegraphics{lion}}.  If you use the graphicx package then you can accomplish the same thing with optional arguments to \includegraphics (see \includegraphics).

The \reflectbox command abbreviates \scalebox{-1}[1]{MATERIAL}.  Thus, Able was I\reflectbox{Able was I} will show the phrase Able was I immediately followed by its mirror reflection.

\resizebox
----------

Synopses:

     \resizebox{HORIZONTAL LENGTH}{VERTICAL LENGTH}{MATERIAL}
     \resizebox*{HORIZONTAL LENGTH}{VERTICAL LENGTH}{MATERIAL}

Given a size, such as 3cm, transform MATERIAL to make it that size.  If either HORIZONTAL LENGTH or VERTICAL LENGTH is an exclamation point !  then the other argument is used to determine a scale factor for both directions.

This example makes the graphic be a half inch wide and scales it vertically by the same factor to keep it from being distorted.

     \resizebox{0.5in}{!}{\includegraphics{lion}}

The unstarred form \resizebox takes VERTICAL LENGTH to be the box's height while the starred form \resizebox* takes it to be height+depth.  For instance, make the text have a height+depth of a quarter inch with \resizebox*{!}{0.25in}{\parbox{1in}{This box has both height and depth.}}.

You can use \depth, \height, \totalheight, and \width to refer to the original size of the box.  Thus, make the text two inches wide but keep the original height with \resizebox{2in}{\height}{Two inches}.

Special insertions
******************

LaTeX provides commands for inserting characters that have a special meaning do not correspond to simple characters you can type.

Reserved characters
===================

LaTeX sets aside the following characters for special purposes (for example, the percent sign % is for comments) so they are called reserved characters or special characters.

     # $ % & { } _ ~ ^ \

If you want a reserved character to be printed as itself, in the text body font, for all but the final three characters in that list simply put a backslash \ in front of the character.  Thus, \$1.23 will produce $1.23 in your output.

As to the last three characters, to get a tilde in the text body font use \~{} (omitting the curly braces would result in the next character receiving a tilde accent).  Similarly, to get a get a text body font circumflex use \^{}.  A text body font backslash results from \textbackslash{}.

To produce the reserved characters in a typewriter font use \verb!!, as below.

     \begin{center}
       \# \$ \% \& \{ \} \_ \~{} \^{} \textbackslash \\
       \verb!# $ % & { } _ ~ ^ \!
     \end{center}

In that example the double backslash \\ is only there to split the lines.

Upper and lower case
====================

Synopsis:

     \uppercase{TEXT}
     \lowercase{TEXT}
     \MakeUppercase{TEXT}
     \MakeLowercase{TEXT}

Change the case of characters.  The TeX primitives commands \uppercase and \lowercase only work for American characters. The LaTeX commands \MakeUppercase and \MakeLowercase commands also change characters accessed by commands such as \ae or \aa.  The commands \MakeUppercase and \MakeLowercase are robust but they have moving arguments (see \protect).

These commands do not change the case of letters used in the name of a command within TEXT.  But they do change the case of every other Latin letter inside the argument TEXT.  Thus, \MakeUppercase{Let $y=f(x)$} produces LET Y=F(X).  Another example is that the name of an environment will be changed, so that \MakeUppercase{\begin{tabular} ... \end{tabular}} will produce an error because the first half is changed to \begin{TABULAR}.

LaTeX uses the same fixed table for changing case throughout a document, The table used is designed for the font encoding T1; this works well with the standard TeX fonts for all Latin alphabets but will cause problems when using other alphabets.

To change the case of text that results from a macro inside TEXT you need to do expansion.  Here the \Schoolname produces COLLEGE OF MATHEMATICS.

     \newcommand{\schoolname}{College of Mathematics}
     \newcommand{\Schoolname}{\expandafter\MakeUppercase
                                \expandafter{\schoolname}}

The textcase package brings some of the missing feature of the standard LaTeX commands \MakeUppercase and \MakeLowerCase.

To uppercase only the first letter of words, you can use the package mfirstuc.

Symbols by font position
========================

You can access any character of the current font using its number with the \symbol command. For example, the visible space character used in the \verb* command has the code decimal 32, so it can be typed as \symbol{32}.

You can also specify numbers in octal (base 8) by using a ' prefix, or hexadecimal (base 16) with a " prefix, so the previous example could also be written as \symbol{'40} or \symbol{"20}.

Text symbols
============

LaTeX provides commands to generate a number of non-letter symbols in running text.  Some of these, especially the more obscure ones, are not available in OT1; you may need to load the textcomp package.

\copyright
\textcopyright
     The copyright symbol, ©.

\dag
     The dagger symbol (in text).

\ddag
     The double dagger symbol (in text).

\LaTeX
     The LaTeX logo.

\LaTeXe
     The LaTeX2e logo.

\guillemotleft («)
\guillemotright (»)
\guilsinglleft (‹)
\guilsinglright (›)
     Double and single angle quotation marks, commonly used in French: «, », ‹, ›.

\ldots
\dots
\textellipsis
     An ellipsis (three dots at the baseline): `...'.  \ldots and \dots also work in math mode.

\lq
     Left (opening) quote: `.

\P
\textparagraph
     Paragraph sign (pilcrow):.

\pounds
\textsterling
     English pounds sterling: £.

\quotedblbase („)
\quotesinglbase (‚)
     Double and single quotation marks on the baseline: „ and ‚.

\rq
     Right (closing) quote: '.

\S
     \itemx \textsection Section sign:.

\TeX
     The TeX logo.

\textasciicircum
     ASCII circumflex: ^.

\textasciitilde
     ASCII tilde: ~.

\textasteriskcentered
     Centered asterisk: *.

\textbackslash
     Backslash: \.

\textbar
     Vertical bar: |.

\textbardbl
     Double vertical bar.

\textbigcircle
     Big circle symbol.

\textbraceleft
     Left brace: {.

\textbraceright
     Right brace: }.

\textbullet
     Bullet: *.

\textcircled{LETTER}
     LETTER in a circle, as in ®.

\textcompwordmark
\textcapitalcompwordmark
\textascendercompwordmark
     Composite word mark (invisible).  The \textcapital... form has the cap height of the font, while the \textascender... form has the ascender height.

\textdagger
     Dagger: \dag.

\textdaggerdbl
     Double dagger: \ddag.

\textdollar (or \$)
     Dollar sign: $.

\textemdash (or ---)
     Em-dash: --- (for punctuation).

\textendash (or --)
     En-dash: -- (for ranges).

\texteuro
     The Euro symbol: €.

\textexclamdown (or !`)
     Upside down exclamation point: ¡.

\textgreater
     Greater than: >.

\textless
     Less than: <.

\textleftarrow
     Left arrow.

\textordfeminine
\textordmasculine
     Feminine and masculine ordinal symbols: ª, º.

\textperiodcentered
     Centered period:.

\textquestiondown (or ?`)
     Upside down question mark: ¿.

\textquotedblleft (or ``)
     Double left quote: ``.

\textquotedblright (or '')
     Double right quote: ''.

\textquoteleft (or `)
     Single left quote: `.

\textquoteright (or ')
     Single right quote: '.

\textquotesingle
     Straight single quote.  (From TS1 encoding.)

\textquotestraightbase
\textquotestraightdblbase
     Single and double straight quotes on the baseline.

\textregistered
     Registered symbol: ®.

\textrightarrow
     Right arrow.

\textthreequartersemdash
     ``Three-quarters'' em-dash, between en-dash and em-dash.

\texttrademark
     Trademark symbol:.

\texttwelveudash
     ``Two-thirds'' em-dash, between en-dash and em-dash.

\textunderscore
     Underscore: _.

\textvisiblespace
     Visible space symbol.

Accents
=======

LaTeX has wide support for many of the world's scripts and languages, through the babel package and related support.  This section does not attempt to cover all that support.  It merely lists the core LaTeX commands for creating accented characters.

The \capital... commands produce alternative forms for use with capital letters.  These are not available with OT1.

\"
\capitaldieresis
     Produces an umlaut (dieresis), as in ö.

\'
\capitalacute
     Produces an acute accent, as in ó.  In the tabbing environment, pushes current column to the right of the previous column (see tabbing).

\.
     Produces a dot accent over the following, as in ȯ.

\=
\capitalmacron
     Produces a macron (overbar) accent over the following, as in ō.

\^
\capitalcircumflex
     Produces a circumflex (hat) accent over the following, as in ô.

\`
\capitalgrave
     Produces a grave accent over the following, as in ò.  In the tabbing environment, move following text to the right margin (see tabbing).

\~
\capitaltilde
     Produces a tilde accent over the following, as in ñ.

\b
     Produces a bar accent under the following, as in o̱. See also \underbar hereinafter.

\c
\capitalcedilla
     Produces a cedilla accent under the following, as in ç.

\d
\capitaldotaccent
     Produces a dot accent under the following, as in ọ.

\H
\capitalhungarumlaut
     Produces a long Hungarian umlaut accent over the following, as in ő.

\i
     Produces a dotless i, as in `ı'.

\j
     Produces a dotless j, as in `ȷ'.

\k
\capitalogonek
     Produces a letter with ogonek, as in `ǫ'.  Not available in the OT1 encoding.

\r
\capitalring
     Produces a ring accent, as in `o̊'.

\t
\capitaltie
\newtie
\capitalnewtie
     Produces a tie-after accent, as in `o͡o'.  The \newtie form is centered in its box.

\u
\capitalbreve
     Produces a breve accent, as in `ŏ'.

\underbar
     Not exactly an accent, this produces a bar under the argument text. The argument is always processed in horizontal mode.  The bar is always a fixed position under the baseline, thus crossing through descenders.  See also \underline in Math miscellany. See also \b above.

\v
\capitalcaron
     Produces a háček (check, caron) accent, as in `ǒ'.

Additional Latin letters
========================

Here are the basic LaTeX commands for inserting letters (beyond A--Z) extending the Latin alphabet, used primarily in languages other than English.

\aa
\AA
     å and Å.

\ae
\AE
     æ and Æ.

\dh
\DH
     Icelandic letter eth: ð and Ð. Not available with OT1 encoding, you need the fontenc package to select an alternate font encoding, such as T1.

\dj
\DJ
     Crossed d and D, a.k.a. capital and small letter d with stroke.  Not available with OT1 encoding, you need the fontenc package to select an alternate font encoding, such as T1.

\ij
\IJ
     ij and IJ (except somewhat closer together than appears here).

\l
\L
     ł and Ł.

\ng
\NG
     Lappish letter eng, also used in phonetics.

\o
\O
     ø and Ø.

\oe
\OE
     œ and Œ.

\ss
\SS
     ß and SS.

\th
\TH
     Icelandic letter thorn: þ and Þ. Not available with OT1 encoding, you need the fontenc package to select an alternate font encoding, such as T1.

\rule
=====

Synopsis:

     \rule[RAISE]{WIDTH}{THICKNESS}

The \rule command produces rules, that is, lines or rectangles.  The arguments are:

raise
     How high to raise the rule (optional).

width
     The length of the rule (mandatory).

thickness
     The thickness of the rule (mandatory).

\today
======

The \today command produces today's date, in the format MONTH DD, YYYY; for example, July 4, 1976. It uses the predefined counters \day, \month, and \year (see \day \month \year) to do this.  It is not updated as the program runs.

Multilingual packages like babel or classes like lettre, among others, will localize \today. For example, the following will output 4 juillet 1976:

     \year=1976 \month=7 \day=4
     \documentclass{minimal}
     \usepackage[french]{babel}
     \begin{document}
     \today
     \end{document}

The datetime package, among others, can produce a wide variety of other date formats.

Splitting the input
*******************

A large document requires a lot of input.  Rather than putting the whole input in a single large file, it's more efficient to split it into several smaller ones.  Regardless of how many separate files you use, there is one that is the root file; it is the one whose name you type when you run LaTeX.

See filecontents, for an environment that allows bundling an external file to be created with the main document.

\include
========

Synopsis:

     \include{FILE}

If no \includeonly command is present, the \include command executes \clearpage to start a new page (see \clearpage), then reads FILE, then does another \clearpage.

Given an \includeonly command, the \include actions are only run if FILE is listed as an argument to \includeonly.  See \includeonly.

The \include command may not appear in the preamble or in a file read by another \include command.

\includeonly
============

Synopsis:

     \includeonly{FILE1,FILE2,...}

The \includeonly command controls which files will be read by subsequent \include commands.  The list of filenames is comma-separated. Each element FILE1, FILE2, ... must exactly match a filename specified in a \include command for the selection to be effective.

This command can only appear in the preamble.

\input
======

Synopsis:

     \input{FILE}

The \input command causes the specified FILE to be read and processed, as if its contents had been inserted in the current file at that point.

If FILE does not end in .tex (e.g., foo or foo.bar), it is first tried with that extension (foo.tex or foo.bar.tex).  If that is not found, the original FILE is tried (foo or foo.bar).

Front/back matter
*****************

Tables of contents
==================

A table of contents is produced with the \tableofcontents command.  You put the command right where you want the table of contents to go; LaTeX does the rest for you.  A previous run must have generated a .toc file.

The \tableofcontents command produces a heading, but it does not automatically start a new page.  If you want a new page after the table of contents, write a \newpage command after the \tableofcontents command.

The analogous commands \listoffigures and \listoftables produce a list of figures and a list of tables (from .lof and .lot files), respectively.  Everything works exactly the same as for the table of contents.

The command \nofiles overrides these commands, and prevents any of these lists from being generated.

\addcontentsline
----------------

Synopsis:

     \addcontentsline{EXT}{UNIT}{TEXT}

The \addcontentsline command adds an entry to the specified list or table where:

ext
     The filename extension of the file on which information is to be written, typically one of: toc (table of contents), lof (list of figures), or lot (list of tables).

unit
     The name of the sectional unit being added, typically one of the following, matching the value of the EXT argument:

     toc
          The name of the sectional unit: part, chapter, section, subsection, subsubsection.

     lof
          For the list of figures: figure.

     lot
          For the list of tables: table.

text
     The text of the entry.

What is written to the .EXT file is the command \contentsline{UNIT}{TEXT}{NUM}, where NUM is the current value of counter UNIT.

\addtocontents
--------------

The \addtocontents{EXT}{TEXT} command adds text (or formatting commands) directly to the .EXT file that generates the table of contents or lists of figures or tables.

ext
     The extension of the file on which information is to be written, typically one of: toc (table of contents), lof (list of figures), or lot (list of tables).

text
     The text to be written.

Glossaries
==========

The command \makeglossary enables creating glossaries.

The command \glossary{TEXT} writes a glossary entry for TEXT to an auxiliary file with the .glo extension.

Specifically, what gets written is the command \glossaryentry{TEXT}{PAGENO}, where PAGENO is the current \thepage value.

The glossary package on CTAN provides support for fancier glossaries.

Indexes
=======

The command \makeindex enables creating indexes.  Put this in the preamble.

The command \index{TEXT} writes an index entry for TEXT to an auxiliary file named with the .idx extension.

Specifically, what gets written is the command \indexentry{TEXT}{PAGENO}, where PAGENO is the current \thepage value.

To generate a index entry for `bar' that says `See foo', use a vertical bar: \index{bar|see{foo}}.  Use seealso instead of see to make a `See also' entry.

The text `See' is defined by the macro \seename, and `See also' by the macro \alsoname.  These can be redefined for other languages.

The generated .idx file is then sorted with an external command, usually either makeindex (http://mirror.ctan.org/indexing/makeindex) or (the multi-lingual) xindy (http://xindy.sourceforge.net). This results in a .ind file, which can then be read to typeset the index.

The index is usually generated with the \printindex command. This is defined in the makeidx package, so \usepackage{makeidx} needs to be in the preamble.

The rubber length \indexspace is inserted before each new letter in the printed index; its default value is 10pt plus5pt minus3pt.

The showidx package causes each index entries to be shown in the margin on the page where the entry appears.  This can help in preparing the index.

The multind package supports multiple indexes.  See also the TeX FAQ entry on this topic, http://www.tex.ac.uk/cgi-bin/texfaq2html?label=multind.

Letters
*******

Synopsis:

     \documentclass{letter}
     \address{SENDER ADDRESS}
     \signature{SENDER NAME}
     \begin{document}
     \begin{letter}{RECIPIENT ADDRESS}
     \opening{SALUTATION}
       LETTER BODY
     \closing{CLOSING TEXT}
     \end{letter}
     ...  more letters ...
     \end{document}

Produce one or more letters.

Each letter is in a separate letter environment, whose argument RECIPIENT ADDRESS often contains multiple lines separated with a double backslash (\\).  For example, you might have:

      \begin{letter}{Mr. Joe Smith \\
           2345 Princess St. \\
           Edinburgh, EH1 1AA}
        ...
      \end{letter}

The start of the letter environment resets the page number to 1, and the footnote number to 1 also.

The SENDER ADDRESS and SENDER NAME are common to all of the letters, whether there is one or more, so these are best put in the preamble.  As with the recipient address, often SENDER ADDRESS contains multiple lines separated by a double backslash (\\).  LaTeX will put the SENDER NAME under the closing, after a vertical space for the traditional hand-written signature; it also can contain multiple lines.

Each letter environment body begins with a required \opening command such as \opening{Dear Madam or Sir:}.  The LETTER BODY text is ordinary LaTeX so it can contain everything from enumerated lists to displayed math, except that commands such as \chapter that make no sense in a letter are turned off.  Each letter environment body typically ends with a \closing command such as \closing{Yours,}.

Additional material may come after the \closing.  You can say who is receiving a copy of the letter with a command like \cc{the Boss \\ the Boss's Boss}.  There's a similar \encl command for a list of enclosures.  And, you can add a postscript with \ps.

LaTeX's default is to indent the signature and the \closing above it by a length of \longindentation.  By default this is 0.5\textwidth. To make them flush left, put \setlength{\longindentation}{0em} in your preamble.

To set a fixed date use something like \renewcommand{\today}{2015-Oct-12}.  If put in your preamble then it will apply to all the letters.

This example shows only one letter environment.  The three lines marked as optional are typically omitted.

     \documentclass{letter}
     \address{Sender's street \\ Sender's town}
     \signature{Sender's name \\ Sender's title}
     % optional: \location{Mailbox 13}
     % optional: \telephone{(102) 555-0101}
     \begin{document}
     \begin{letter}{Recipient's name \\ Recipient's address}
     \opening{Sir:}
     % optional: \thispagestyle{firstpage}
     I am not interested in entering a business arrangement with you.
     \closing{Your most humble, etc.,}
     \end{letter}
     \end{document}

These commands are used with the letter class.

\address
========

Synopsis:

     \address{SENDERS ADDRESS}

Specifies the return address as it appears on the letter and on the envelope.  Separate multiple lines in SENDERS ADDRESS with a double backslash \\.

Because it can apply to multiple letters this declaration is often put in the preamble.  However, it can go anywhere, including inside an individual letter environment.

This command is optional: without the \address declaration the letter is formatted with some blank space on top, for copying onto pre-printed letterhead paper.  (see Overview, for details on your local implementation.)  With the \address declaration, it is formatted as a personal letter.

Here is an example.

     \address{Stephen Maturin \\
              The Grapes of the Savoy}

\cc
===

Synopsis:

     \cc{FIRST NAME \\
          ... }

Produce a list of names to which copies of the letter were sent.  This command is optional.  If it appears then typically it comes after \closing.  Separate multiple lines with a double backslash \\, as in:

     \cc{President \\
         Vice President}

\closing
========

Synopsis:

     \closing{TEXT}

Usually at the end of a letter, above the handwritten signature, there is a \closing (although this command is optional).  For example,

     \closing{Regards,}

\encl
=====

Synopsis:

     \encl{FIRST ENCLOSED OBJECT \\
            ... }

Produce a list of things included with the letter. This command is optional; when it is used, it typically is put after \closing. Separate multiple lines with a double backslash \\.

     \encl{License \\
            Passport }

\location
=========

Synopsis:

     \location{TEXT}

The TEXT appears centered at the bottom of the each page.  It only appears if the page style is firstpage.

\makelabels
===========

Synopsis:

     \makelabels

Create a sheet of address labels from the recipient addresses, one for each letter. This sheet will be output before the letters, with the idea that you can copy it to a sheet of peel-off labels.  This command goes in the preamble.

Customize the labels by redefining the commands \startlabels, \mlabel, and \returnaddress in the preamble.  The command \startlabels sets the width, height, number of columns, etc., of the page onto which the labels are printed.  The command \mlabel{SENDER ADDRESS}{RECIPIENT ADDRESS} produces the two labels (or one, if you choose to ignore the SENDER ADDRESS). The SENDER ADDRESS is the value returned by the macro \returnaddress while RECIPIENT ADDRESS is the value passed in the argument to the letter environment.  By default \mlabel ignores the first argument, the SENDER ADDRESS.

\name
=====

Synopsis:

     \name{NAME}

Sender's name, used for printing on the envelope together with the return address.

\opening
========

Synopsis:

     \opening{TEXT}

This command is required.  It starts a letter, following the \begin{letter}{...}. The mandatory argument TEXT is the text that starts your letter.  For instance:

     \opening{Dear John:}

\ps
===

Synopsis:

     \ps{TEXT}

Add a postscript.  This command is optional and usually is used after \closing.

     \ps{P.S. After you have read this letter, burn it. Or eat it.}

\signature
==========

Synopsis:

     \signature{FIRST LINE \\
                 ... }

The sender's name.  This command is optional, although its inclusion is usual.

The argument text appears at the end of the letter, after the closing and after a vertical space for the traditional hand-written signature. Separate multiple lines with a double backslash \\.  For example:

     \signature{J Fred Muggs \\
                White House}

LaTeX's default for the vertical space from the \closing text down to the \signature text is 6\medskipamount, which is six times 0.7em.

This command is usually in the preamble, to apply to all the letters in the document.  To have it apply to one letter only, put it inside a letter environment and before the \closing.

You can include a graphic in the signature, for instance with \signature{\vspace{-6\medskipamount}\includegraphics{sig.png}\\ My name} (this requires writing \usepackage{graphicx} in the preamble).

\telephone
==========

Synopsis:

     \telephone{NUMBER}

The sender's telephone number.  This is typically in the preamble, where it applies to all letters.  This only appears if the firstpage pagestyle is selected.  If so, it appears on the lower right of the page.

Terminal input/output
*********************

\typein[CMD]{MSG}
=================

Synopsis:

     \typein[\CMD]{MSG}

\typein prints MSG on the terminal and causes LaTeX to stop and wait for you to type a line of input, ending with return.  If the optional \CMD argument is omitted, the typed input is processed as if it had been included in the input file in place of the \typein command.  If the \CMD argument is present, it must be a command name.  This command name is then defined or redefined to be the typed input.

\typeout{MSG}
=============

Synopsis:

     \typeout{MSG}

Prints msg on the terminal and in the log file. Commands in msg that are defined with \newcommand or \renewcommand (among others) are replaced by their definitions before being printed.

LaTeX's usual rules for treating multiple spaces as a single space and ignoring spaces after a command name apply to msg.  A \space command in msg causes a single space to be printed, independent of surrounding spaces.  A ^^J in msg prints a newline.

Command line
************

The input file specification indicates the file to be formatted; TeX uses .tex as a default file extension.  If you omit the input file entirely, TeX accepts input from the terminal.  You can also specify arbitrary LaTeX input by starting with a backslash. For example, this processes foo.tex without pausing after every error:

     latex '\nonstopmode\input foo.tex'

With many, but not all, implementations, command-line options can also be specified in the usual Unix way, starting with - or --.  For a list of those options, try latex --help.

If LaTeX stops in the middle of the document and gives you a * prompt, it is waiting for input.  You can type \stop (and return) and it will prematurely end the document.

See TeX engines, for other system commands invoking LaTeX.

Document templates
******************

Although not reference material, perhaps these document templates will be useful.  Additional template resources are listed at http://tug.org/interest.html#latextemplates.

beamer template
===============

The beamer class creates presentation slides.  It has a vast array of features, but here is a basic template:

\documentclass{beamer}

\title{Beamer Class template}
\author{Alex Author}
\date{July 31, 2007}

\begin{document}

\maketitle

% without [fragile], any {verbatim} code gets mysterious errors.
\begin{frame}[fragile]
 \frametitle{First Slide}

\begin{verbatim}
  This is \verbatim!
\end{verbatim}

\end{frame}

\end{document}

One web resource for this: http://robjhyndman.com/hyndsight/beamer/.

book template
=============

\documentclass{book}
\title{Book Class Template}
\author{Alex Author}

\begin{document}
\maketitle

\chapter{First}
Some text.

\chapter{Second}
Some other text.

\section{A subtopic}
The end.
\end{document}

tugboat template
================

TUGboat is the journal of the TeX Users Group, http://tug.org/TUGboat.

\documentclass{ltugboat}

\usepackage{graphicx}
\usepackage{ifpdf}
\ifpdf
\usepackage[breaklinks,hidelinks]{hyperref}
\else
\usepackage{url}
\fi

%%% Start of metadata %%%

\title{Example \TUB\ article}

% repeat info for each author.
\author{First Last}
\address{Street Address \\ Town, Postal \\ Country}
\netaddress{user (at) example dot org}
\personalURL{http://example.org/~user/}

%%% End of metadata %%%

\begin{document}

\maketitle

\begin{abstract}
This is an example article for \TUB{}.
Please write an abstract.
\end{abstract}

\section{Introduction}

This is an example article for \TUB, linked from
\url{http://tug.org/TUGboat/location.html}.

We recommend the \texttt{graphicx} package for image inclusions, and the
\texttt{hyperref} package if active urls are desired (in the \acro{PDF}
output).  Nowadays \TUB\ is produced using \acro{PDF} files exclusively.

The \texttt{ltugboat} class provides these abbreviations (and many more):
% verbatim blocks are often better in \small
\begin{verbatim}[\small]
\AllTeX \AMS \AmS \AmSLaTeX \AmSTeX \aw \AW
\BibTeX \CTAN \DTD \HTML
\ISBN \ISSN \LaTeXe
\mf \MFB
\plain \POBox \PS
\SGML \TANGLE \TB \TP
\TUB \TUG \tug
\UNIX \XeT \WEB \WEAVE

\, \bull \Dash \dash \hyph

\acro{FRED} -> {\small[er] fred}  % please use!
\cs{fred}   -> \fred
\meta{fred} -> <fred>
\nth{n}     -> 1st, 2nd, ...
\sfrac{3/4} -> 3/4
\booktitle{Book of Fred}
\end{verbatim}

For references to other \TUB\ issue, please use the format
\textsl{volno:issno}, e.g., ``\TUB\ 32:1'' for our \nth{100} issue.

This file is just a template.  The \TUB\ style documentation is the
\texttt{ltubguid} document at \url{http://ctan.org/pkg/tugboat}.  (For
\CTAN\ references, where sensible we recommend that form of url, using
\texttt{/pkg/}; or, if you need to refer to a specific file location,
\texttt{http://mirror.ctan.org/\textsl{path}}.)

Email \verb|tugboat@tug.org| if problems or questions.

\bibliographystyle{plain}  % we recommend the plain bibliography style
\nocite{book-minimal}      % just making the bibliography non-empty
\bibliography{xampl}       % xampl.bib comes with BibTeX

\makesignature
\end{document}