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+% \iffalse
+%
+%% File `euler.dtx'.
+%% Copyright (C) 1992 Frank Jensen.  All rights reserved.
+%% Copyright (C) 1993--1995 Frank Jensen and Frank Mittelbach.
+%% All rights reserved.
+%
+% Please send error reports and suggestions for improvements to:
+%
+%                          Frank Jensen
+%                          Aalborg University
+%                          DK-9220 Aalborg \O
+%                          Denmark
+%               Internet:  <fj@iesd.auc.dk>
+%
+% \fi
+
+\def\fileversion{v2.5}
+\def\filedate{1995/03/05}
+
+% \CheckSum{606}
+%% \CharacterTable
+%%  {Upper-case    \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z
+%%   Lower-case    \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z
+%%   Digits        \0\1\2\3\4\5\6\7\8\9
+%%   Exclamation   \!     Double quote  \"     Hash (number) \#
+%%   Dollar        \$     Percent       \%     Ampersand     \&
+%%   Acute accent  \'     Left paren    \(     Right paren   \)
+%%   Asterisk      \*     Plus          \+     Comma         \,
+%%   Minus         \-     Point         \.     Solidus       \/
+%%   Colon         \:     Semicolon     \;     Less than     \<
+%%   Equals        \=     Greater than  \>     Question mark \?
+%%   Commercial at \@     Left bracket  \[     Backslash     \\
+%%   Right bracket \]     Circumflex    \^     Underscore    \_
+%%   Grave accent  \`     Left brace    \{     Vertical bar  \|
+%%   Right brace   \}     Tilde         \~}
+%
+% \iffalse
+%<*driver>
+\documentclass{ltxdoc}
+\begin{document}
+   \DocInput{euler.dtx}
+\end{document}
+%</driver>
+% \fi
+%
+% \newcommand\beton{\texttt{beton}}
+% \newcommand\euler{\texttt{euler}}
+% \newcommand\MF{Metafont}
+%
+% \title{The \euler\ package}
+% \author{Frank Jensen\thanks{Updates by Frank Mittelbach.}}
+% \date{\filedate}
+%
+% \maketitle
+%
+% \section{Introduction}
+%
+% The \euler\ package provides a setup for using the AMS Euler family
+% of fonts for math in \LaTeX\ documents.  The AMS Euler family was
+% designed by Hermann Zapf, commissioned by the American Mathematical
+% Society.  ``The underlying philosophy of Zapf's Euler design was to
+% capture the flavor of mathematics as it might be written by a
+% mathematician with excellent handwriting.''~\cite{concrete-tug} 
+%
+% The \euler\ package is based on Knuth's macros for the book
+% ``Concrete Mathematics''~\cite{concrete}.  Knuth's macros can be
+% found through anonymous ftp to \texttt{labrea.\allowbreak
+% stanford.edu}: look for the file \texttt{gkpmac.tex} in directory
+% \texttt{pub/tex/local/lib}.  The Euler fonts can be found through
+% anonymous ftp to \texttt{e-math.ams.org}: look in directory
+% \texttt{pub/tex/amsfonts}.
+%
+% The purpose of the \euler\ package is to provide the math part of
+% the look of~\cite{concrete}.  The other part (text fonts) is
+% provided by the \beton\ package.  The reason for creating two
+% packages is to make it easy to use the Euler math fonts together
+% with other text fonts (in particular, it appears that the Euler
+% fonts match many of the popular PostScript fonts pretty well).
+%
+% Basically, the \euler\ package provides the same setup (the same
+% definitions, math codes, etc.)\ as \texttt{gkpmac.tex} with respect
+% to the Euler fonts.  However, Knuth~\cite{concrete-tug} admits that
+% the macros were written for one specific project, namely to typeset
+% the ``Concrete Mathematics'' book~\cite{concrete}.  So, the \euler\
+% package actually does a little more than \texttt{gkpmac.tex}: for
+% example, some `exotic' symbols, present in CM math italic, are
+% missing from the Euler fonts; the \euler\ package takes care of this
+% (whereas \texttt{gkpmac.tex} does not).
+%
+% The use of the \euler\ package requires a lot of care when entering
+% the manuscript, since the package will cause, e.g., math numerals to
+% come from the Euler Roman fonts; these numerals are easily
+% distinguished from the normal text numerals.  This implies that
+% sloppy typing is clearly exposed: imagine how 
+% ``|$x$ is either 1 or $-1$|'' will appear when typeset!  In general,
+% the typist will in each case have to decide whether an input
+% fragment is a math or a non-math entity.  This holds true even for
+% the tiniest details, such as punctuation characters (parentheses,
+% colons, semicolons, commas, and periods).
+%
+% Finally, a few words about the technical quality of the fonts (there
+% are no doubts about their artistic quality): The fonts are not tuned
+% for low resolution rendering: I recommend at least 600dpi.  The
+% fonts employ none of the tuning machinery of CM: e.g., they do not
+% use the `blacker' parameter specified in each \MF\ mode definition,
+% indicating that they might look somewhat light on printers that
+% normally require a large `blacker' value.
+%
+% \section{What the \euler\ package provides}
+%
+% The \euler\ package defines two new math alphabet identifiers,
+% |\mathscr| (Euler Script, uppercase letters only) and |\mathfrak|
+% (Euler Fraktur, both lowercase and uppercase letters).
+%
+% By default, the original meaning of |\mathcal| is preserved, but if
+% the \euler\ package is loaded with the \texttt{mathcal} option,
+% |\mathcal| will produce Euler Script letters instead of the usual
+% Computer Modern calligraphic letters.
+%
+% Also, by default, the \euler\ package does not redefine the
+% |\mathbf| math alphabet identifier; it will still produce bold CM
+% letters and digits.  However, loading the \euler\ package with the
+% \texttt{mathbf} option will cause |\mathbf| to produce bold Euler
+% Roman letters and digits.  Another way to get bold symbols is to use
+% the |\boldsymbol| command provided by the \texttt{amsbsy} package
+% (part of AMS-\LaTeX).
+%
+% Some users do not like the |\hat| accent glyph present in the Euler
+% fonts (the \euler\ package uses this accent glyph be default).  To
+% use the |\hat| accent glyph from the text font instead, load the
+% \euler\ package with the \texttt{text-hat-accent} option.
+%
+% In \cite{concrete}, the space around relations in displays was
+% increased (from `5mu plus 5mu' to `10mu minus 3mu').  The \euler\
+% package does not change this space, since this is (for most cases)
+% controlled by the \LaTeX\ \texttt{eqnarray} environment.  Also,
+% in~\cite{concrete}, displays are left justified with a suitable
+% indentation; we leave such matters to the general layout.
+%
+% \StopEventually {
+% \begin{thebibliography}{1}
+%    \bibitem{concrete}
+%       \textsc{R. L. Graham}, \textsc{D. E. Knuth}, and
+%       \textsc{O. Patashnik}.
+%       \newblock \textit{Concrete Mathematics}.
+%       \newblock Addison-Wesley, 1989. 
+%    \bibitem{concrete-tug}
+%       \textsc{D. E. Knuth}.
+%       \newblock Typesetting Concrete Mathematics.
+%       \newblock \textsl{TUGboat} 10(1):31--36, 1989.
+% \end{thebibliography}
+% }
+%
+% \section{Hello world}
+%
+% First, we announce the package.
+%    \begin{macrocode}
+%<*package>
+\NeedsTeXFormat{LaTeX2e}[1994/12/01]
+\ProvidesPackage{euler}[\filedate\space\fileversion]
+\typeout{Package: `euler' \fileversion\space <\filedate> (FJ and FMi)}
+%    \end{macrocode}
+%
+% \section{Font and other definitions}
+%
+% The AMS Euler family consists of: Euler Roman (medium and bold),
+% Euler Fraktur (medium and bold), Euler Script (medium and bold), and
+% Euler Extension (medium only).  The \texttt{.fd} files for these
+% fonts are defined in the \texttt{amsfonts.fdd} file (part of the
+% AMSFonts distribution).
+%
+% \subsection{Euler Roman}
+%
+% The Euler Roman fonts replace the Computer Modern Math Italic fonts,
+% located in the `letters' math symbol font:
+%    \begin{macrocode}
+\DeclareSymbolFont{letters}{U}{eur}{m}{n}
+\SetSymbolFont{letters}{bold}{U}{eur}{b}{n}
+%    \end{macrocode}
+%
+% In math mode, digits should come from the Euler Roman fonts.  As in
+% standard \LaTeX, we assign the type |\mathalpha| to the digits which
+% means that they will vary with math alphabets.  One of the reasons
+% for this is that footnote numbers are set in math mode, and we want
+% these numbers to come from the text font; this is accomplished by
+% setting the \TeX\ primitive |\fam| to zero.  (See
+% Section~\ref{footnotes} below.)
+%    \begin{macrocode}
+\DeclareMathSymbol{0}\mathalpha{letters}{"30}
+\DeclareMathSymbol{1}\mathalpha{letters}{"31}
+\DeclareMathSymbol{2}\mathalpha{letters}{"32}
+\DeclareMathSymbol{3}\mathalpha{letters}{"33}
+\DeclareMathSymbol{4}\mathalpha{letters}{"34}
+\DeclareMathSymbol{5}\mathalpha{letters}{"35}
+\DeclareMathSymbol{6}\mathalpha{letters}{"36}
+\DeclareMathSymbol{7}\mathalpha{letters}{"37}
+\DeclareMathSymbol{8}\mathalpha{letters}{"38}
+\DeclareMathSymbol{9}\mathalpha{letters}{"39}
+%    \end{macrocode}
+% The uppercase greek letters are also taken from the Euler Roman
+% fonts.  We make them ordinary symbols (i.e., of type |\mathord|) as
+% opposed to \texttt{plain.tex}, \texttt{gkpmac.tex}, and standard
+% \LaTeX, which make them vary according to |\fam|.
+%    \begin{macrocode}
+\DeclareMathSymbol\Gamma  \mathord{letters}{"00}
+\DeclareMathSymbol\Delta  \mathord{letters}{"01}
+\DeclareMathSymbol\Theta  \mathord{letters}{"02}
+\DeclareMathSymbol\Lambda \mathord{letters}{"03}
+\DeclareMathSymbol\Xi     \mathord{letters}{"04}
+\DeclareMathSymbol\Pi     \mathord{letters}{"05}
+\DeclareMathSymbol\Sigma  \mathord{letters}{"06}
+\DeclareMathSymbol\Upsilon\mathord{letters}{"07}
+\DeclareMathSymbol\Phi    \mathord{letters}{"08}
+\DeclareMathSymbol\Psi    \mathord{letters}{"09}
+\DeclareMathSymbol\Omega  \mathord{letters}{"0A}
+%    \end{macrocode}
+% Euler doesn't have the special variants of |\sigma| and |\rho|:
+%    \begin{macrocode}
+\let\varsigma=\sigma
+\let\varrho=\rho
+%    \end{macrocode}
+%
+% \begin{macro}{\mathbf}
+% If the \euler\ package is loaded with the \texttt{mathbf}
+% option, |\mathbf| should produce bold Euler Roman letters and
+% digits.
+%    \begin{macrocode}
+\DeclareOption{mathbf}
+   {\AtBeginDocument{\DeclareMathAlphabet\mathbf{U}{eur}{b}{n}}}
+%    \end{macrocode}
+% \end{macro}
+% Note the use of |\AtBeginDocument|; it ensures that the redefinition
+% overrides the default settings (Section~\ref{text-fonts}).
+%
+% \subsection{Euler Fraktur}
+%
+% \begin{macro}{\mathfrak}
+% The Euler Fraktur fonts get their own math symbol font.  We define a
+% math alphabet identifier---|\mathfrak|---to access this symbol font.
+% For compatibility with previous versions of the \euler\
+% package, we define |\frak| as an alias for |\mathfrak| (the
+% \texttt{amsfonts} package also provides this alias).
+%    \begin{macrocode}
+\DeclareSymbolFont{EulerFraktur}{U}{euf}{m}{n}
+\SetSymbolFont{EulerFraktur}{bold}{U}{euf}{b}{n}
+\DeclareSymbolFontAlphabet\mathfrak{EulerFraktur}
+\@ifpackageloaded{amsfonts}{}{\newcommand\frak{\mathfrak}}
+%    \end{macrocode}
+% \end{macro}
+%
+% The following characters come from the Euler Fraktur symbol font (as
+% defined in \texttt{gkpmac.tex}):
+%    \begin{macrocode}
+\DeclareMathSymbol{!}\mathord  {EulerFraktur}{"21}
+\DeclareMathSymbol{(}\mathopen {EulerFraktur}{"28} 
+\DeclareMathSymbol{)}\mathclose{EulerFraktur}{"29} 
+\DeclareMathSymbol{+}\mathbin  {EulerFraktur}{"2B}
+\DeclareMathSymbol{-}\mathbin  {EulerFraktur}{"2D}
+\DeclareMathSymbol{=}\mathrel  {EulerFraktur}{"3D}
+\DeclareMathSymbol{[}\mathopen {EulerFraktur}{"5B}
+\DeclareMathSymbol{]}\mathclose{EulerFraktur}{"5D}
+%    \end{macrocode}
+% There is a curious detail here: The type of `!' is |\mathclose| in
+% \texttt{plain.tex} (and standard \LaTeX) but |\mathord| in
+% \texttt{gkpmac.tex}.  The reason for this is probably that one
+% should not use Euler punctuation characters as part of the
+% text,\footnote{In particular, one should watch out for punctuation
+% characters in displays: Is, e.g., an exclamation point part of a
+% formula or part of the text?  (With Computer Modern, it didn't
+% really matter, but it does matter with Euler!)} and punctuation
+% characters in math are usually operators.  E.g., in CSP
+% (Communicating Sequential Processes), `!'~denotes an output
+% operation, a tightly binding binary operator; there is usually no
+% space around this operator (to indicate the high precedence).
+%
+% The Euler Fraktur symbol font contains more punctuation characters
+% than defined above.  We want to use these characters as they look
+% better when they appear in math formulas (there are some strange
+% looking formulas in~\cite{concrete}).  Even if one may argue that,
+% e.g., semicolon is most often used in the text sense (in displays),
+% it is more consistent and easier to remember if everything in math
+% mode is Euler.
+%    \begin{macrocode}
+\DeclareMathSymbol{"}\mathord  {EulerFraktur}{"7D}
+\DeclareMathSymbol{&}\mathord  {EulerFraktur}{"26}
+\DeclareMathSymbol{:}\mathrel  {EulerFraktur}{"3A}
+\DeclareMathSymbol{;}\mathpunct{EulerFraktur}{"3B}
+\DeclareMathSymbol{?}\mathord  {EulerFraktur}{"3F}
+\DeclareMathSymbol{^}\mathord  {EulerFraktur}{"5E}
+\DeclareMathSymbol{`}\mathord  {EulerFraktur}{"12}
+%    \end{macrocode}
+% Here, we also changed the type of `?' to |\mathord| to be consistent
+% with the type of~`!'.  Regarding the math codes assigned by
+% \texttt{INITEX}: The Euler fonts do not have the glyphs for |\#|,
+% |\$|, |\%|, and \texttt{@}, so these glyphs are still taken from the
+% text fonts.  Note also that we do not set the math code for the
+% other quote character: it is active in math mode (code
+% \texttt{"8000}); it produces primes (and should continue to do so).
+%    \begin{macrocode}
+\DeclareMathDelimiter{(}{EulerFraktur}{"28}{largesymbols}{"00}
+\DeclareMathDelimiter{)}{EulerFraktur}{"29}{largesymbols}{"01}
+\DeclareMathDelimiter{[}{EulerFraktur}{"5B}{largesymbols}{"02}
+\DeclareMathDelimiter{]}{EulerFraktur}{"5D}{largesymbols}{"03}
+%    \end{macrocode}
+%
+% \begin{macro}{\oldstylenums}
+% \begin{macro}{\TextOldstyle}\begin{macro}{\MathOldstyle}
+% We provide a new definition of the |\oldstylenums| macro: this
+% definition allows us to modify the generation of non-aligning (aka
+% ``oldstyle'') numerals in text and in math separately, using two
+% hooks, |\TextOldstyle| and |\MathOldstyle|.
+%    \begin{macrocode}
+\DeclareRobustCommand\oldstylenums[1]%
+  {\begingroup
+      \spaceskip\fontdimen\tw@\font
+      \TextOldstyle \MathOldstyle #1%
+   \endgroup}
+%    \end{macrocode}
+% In math, the |\oldstylenums| macro should produce Euler oldstyle
+% digits (located in the Euler Fraktur fonts):
+%    \begin{macrocode}
+\def\MathOldstyle{\mathgroup\symEulerFraktur}
+%    \end{macrocode}
+% By default, oldstyle digits in text come from the Computer Modern
+% fonts:
+%    \begin{macrocode}
+\providecommand\TextOldstyle{\usefont{OML}{cmm}\f@series{it}}
+%    \end{macrocode}
+% \end{macro}\end{macro}\end{macro}
+%
+% \subsection{Euler Script}
+%
+% \begin{macro}{\mathscr}
+% Like the Euler Fraktur fonts, the Euler Script fonts also get their
+% own symbol font.  We define a math alphabet
+% identifier---|\mathscr|---to access this symbol font.  For
+% compatibility with previous versions of the \euler\ package,
+% we define |\scr| as an alias for |\mathscr|.
+%    \begin{macrocode}
+\DeclareSymbolFont{EulerScript}{U}{eus}{m}{n}
+\SetSymbolFont{EulerScript}{bold}{U}{eus}{b}{n}
+\DeclareSymbolFontAlphabet\mathscr{EulerScript}
+\newcommand\scr{\mathscr}
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\mathcal}
+% If the \euler\ package is loaded with the \texttt{mathcal}
+% option, |\mathcal| should produce Euler Script letters.
+%    \begin{macrocode}
+\DeclareOption{mathcal}{\renewcommand\mathcal{\mathscr}}
+%    \end{macrocode}
+% \end{macro}
+%
+% The following is equivalent to the definitions in \texttt{gkpmac.tex}
+% concerning the Euler Script fonts:
+%    \begin{macrocode}
+\DeclareMathSymbol\aleph\mathord{EulerScript}{"40}
+%\DeclareMathSymbol\equiv\mathrel{EulerScript}{"11}
+%\let\cong=\equiv % lowres bars weren't spaced right
+%\DeclareMathSymbol\leq \mathrel{EulerScript}{"14} 
+%\let\le=\leq % seems to have been eliminated
+%\DeclareMathSymbol\geq \mathrel{EulerScript}{"15} 
+%\let\ge=\geq % ditto
+\DeclareMathSymbol\Re   \mathord{EulerScript}{"3C}
+\DeclareMathSymbol\Im   \mathord{EulerScript}{"3D}
+%    \end{macrocode}
+% Knuth used a slightly different version of the Euler Script fonts
+% that had special `$\le$' and `$\ge$' glyphs.  Actually, the source
+% for the AMS Euler Script medium (but not the bold) font also
+% contains these glyphs; however, they are commented out (no
+% explanation is given).  The definitions of |\equiv| and |\cong| are
+% also commented out in \texttt{gkpmac.tex} (with the reason as given
+% above, i.e., problems with low resolution rendering).
+%    \begin{macrocode}
+\DeclareMathDelimiter\vert
+                 \mathord{EulerScript}{"6A}{largesymbols}{"0C}
+\DeclareMathDelimiter\backslash
+                 \mathord{EulerScript}{"6E}{largesymbols}{"0F}
+%    \end{macrocode}
+%
+% The Euler Script fonts constitute a partial replacement for the
+% Computer Modern `symbols' math symbol fonts.  (None of the remaining
+% definitions in this section were included in \texttt{gkpmac.tex}.)
+%    \begin{macrocode}
+%\DeclareMathSymbol{-}\mathbin{EulerScript}{"00} % already done
+\DeclareMathSymbol{|}\mathord{EulerScript}{"6A}
+\DeclareMathDelimiter{|}{EulerScript}{"6A}{largesymbols}{"0C}
+%    \end{macrocode}
+% (The minus signs in the Euler Fraktur and Script fonts are
+% identical, i.e., the sources are identical.)
+%    \begin{macrocode}
+\DeclareMathSymbol\neg     \mathord{EulerScript}{"3A}
+\let\lnot=\neg
+\DeclareMathSymbol\wedge   \mathbin{EulerScript}{"5E}
+\let\land=\wedge
+\DeclareMathSymbol\vee     \mathbin{EulerScript}{"5F}
+\let\lor=\vee
+\DeclareMathSymbol\setminus\mathbin{EulerScript}{"6E}
+\DeclareMathSymbol\sim     \mathrel{EulerScript}{"18}
+\DeclareMathSymbol\mid     \mathrel{EulerScript}{"6A}
+\DeclareMathDelimiter\arrowvert
+        \mathord{EulerScript}{"6A}{largesymbols}{"3C} % ???
+%    \end{macrocode}
+% (There are no |\approx| or |\simeq| to go with |\sim|.)  In Plain
+% \TeX\null, the characters |{|, |\|, and~|}| are assigned math codes
+% (and |\| is also given a delimiter code); these are the only visible
+% ASCII (7-bit) characters that we don't give a math code (we don't
+% assign math codes to any of the invisible ASCII characters).
+%
+% The Euler Script fonts also contain a section sign~(\S):
+%    \begin{macrocode}
+\DeclareMathSymbol\mathsection\mathord{EulerScript}{"78}
+%    \end{macrocode}
+%
+% \subsection{Euler Extension}
+%
+% We allocate a new symbol font group for this font:
+%    \begin{macrocode}
+\DeclareSymbolFont{EulerExtension}{U}{euex}{m}{n}
+%    \end{macrocode}
+% This font contains some alternative versions of some Computer Modern
+% symbols.  The \texttt{amsmath} package (part of AMS-\LaTeX)
+% redefines the |\coprod|, |\prod|, and |\sum| symbols; to make the
+% \euler\ package work correctly with the \texttt{amsmath}
+% package, we need to take different actions depending on whether the
+% \texttt{amsmath} package has been loaded before the \euler\
+% package or not.  Note: This will \emph{not} work with the
+% \texttt{amstex} package.
+%    \begin{macrocode}
+\@ifpackageloaded{amsmath}
+   {\DeclareMathSymbol\coprod@\mathop{EulerExtension}{"60}%
+    \DeclareMathSymbol\prod@  \mathop{EulerExtension}{"51}%
+    \DeclareMathSymbol\sum@   \mathop{EulerExtension}{"50}}
+   {\DeclareMathSymbol\coprod \mathop{EulerExtension}{"60}%
+    \DeclareMathSymbol\prod   \mathop{EulerExtension}{"51}%
+    \DeclareMathSymbol\sum    \mathop{EulerExtension}{"50}}
+%    \end{macrocode}
+% We shall respectfully ask the user not to use the \texttt{amstex}
+% package.
+%    \begin{macrocode}
+\AtBeginDocument
+   {\@ifpackageloaded{amstex}%
+       {\PackageWarningNoLine{euler}{Please do not use `amstex'.
+                 Use `amsmath' instead}{}}}
+%    \end{macrocode}
+%    \begin{macrocode}
+\DeclareMathSymbol\intop  \mathop {EulerExtension}{"52}
+\DeclareMathSymbol\ointop \mathop {EulerExtension}{"48}
+\DeclareMathSymbol\braceld\mathord{EulerExtension}{"7A} 
+\DeclareMathSymbol\bracerd\mathord{EulerExtension}{"7B}
+\DeclareMathSymbol\bracelu\mathord{EulerExtension}{"7C} 
+\DeclareMathSymbol\braceru\mathord{EulerExtension}{"7D}
+\DeclareMathSymbol\infty  \mathord{EulerExtension}{"31}
+%    \end{macrocode}
+% It is not enough to substitute the Euler integral sign for the
+% Computer Modern integral sign, if we are using the \texttt{amsmath}
+% package.  The multiple integral signs will look bad.  The following
+% will make them look better.
+%    \begin{macrocode}
+\AtBeginDocument
+   {\@ifpackageloaded{amsmath}%
+       {\def\intkern@{\mkern -6mu }%
+        \def\ints@#1{\mkern -3mu
+           \mathop{\mkern 3mu
+              \intop
+              \ifnum #1=\z@ \intdots@ \else
+                 \intkern@
+                 \ifnum #1>\tw@ \intop\intkern@
+                    \ifnum #1>\thr@@ \intop\intkern@ \fi
+                 \fi
+              \fi
+              \intop
+           }\ilimits@
+        }%
+       }{}}
+%    \end{macrocode}
+% All Euler arrows come from the Euler Extension font:
+%    \begin{macrocode}
+\DeclareMathSymbol\nearrow\mathrel{EulerExtension}{"25}
+\DeclareMathSymbol\searrow\mathrel{EulerExtension}{"26}
+\DeclareMathSymbol\nwarrow\mathrel{EulerExtension}{"2D}
+\DeclareMathSymbol\swarrow\mathrel{EulerExtension}{"2E}
+%    \end{macrocode}
+%    \begin{macrocode}
+\DeclareMathSymbol\Leftrightarrow\mathrel{EulerExtension}{"2C}
+\DeclareMathSymbol\Leftarrow     \mathrel{EulerExtension}{"28}
+\DeclareMathSymbol\Rightarrow    \mathrel{EulerExtension}{"29}
+\DeclareMathSymbol\leftrightarrow\mathrel{EulerExtension}{"24}
+\DeclareMathSymbol\leftarrow     \mathrel{EulerExtension}{"20} 
+\let\gets=\leftarrow
+\DeclareMathSymbol\rightarrow    \mathrel{EulerExtension}{"21} 
+\let\to=\rightarrow
+%    \end{macrocode}
+%    \begin{macrocode}
+\DeclareMathDelimiter\uparrow
+              \mathrel{EulerExtension}{"22}{largesymbols}{"78}
+\DeclareMathDelimiter\downarrow
+              \mathrel{EulerExtension}{"23}{largesymbols}{"79}
+\DeclareMathDelimiter\updownarrow
+              \mathrel{EulerExtension}{"6C}{largesymbols}{"3F}
+\DeclareMathDelimiter\Uparrow
+              \mathrel{EulerExtension}{"2A}{largesymbols}{"7E}
+\DeclareMathDelimiter\Downarrow
+              \mathrel{EulerExtension}{"2B}{largesymbols}{"7F}
+\DeclareMathDelimiter\Updownarrow
+              \mathrel{EulerExtension}{"6D}{largesymbols}{"77}
+%    \end{macrocode}
+%    \begin{macrocode}
+\DeclareMathSymbol\leftharpoonup   \mathrel{EulerExtension}{"18}
+\DeclareMathSymbol\leftharpoondown \mathrel{EulerExtension}{"19}
+\DeclareMathSymbol\rightharpoonup  \mathrel{EulerExtension}{"1A}
+\DeclareMathSymbol\rightharpoondown\mathrel{EulerExtension}{"1B}
+%    \end{macrocode}
+%
+% Note the funny mixture of the Euler Script and Extension fonts:
+%    \begin{macrocode}
+\DeclareMathDelimiter\lbrace
+              \mathopen{EulerScript}{"66}{EulerExtension}{"08}
+\DeclareMathDelimiter\rbrace
+             \mathclose{EulerScript}{"67}{EulerExtension}{"09}
+%    \end{macrocode}
+%
+% \section{More math}
+%
+% Actually, we still need some Computer Modern fonts: We need the
+% equals sign for long/extensible (horizontal) double arrows, and we
+% need the minus sign for the single arrows!  The Euler Extension font
+% is based on the \MF\ code for Computer Modern, and we need the
+% Computer Modern equals and minus signs to make long/extensible arrows.
+%
+% We allocate math alphabets to produce the equals and minus signs for
+% arrows.  Note that since Euler arrows are only available in medium
+% weight (they come from the Euler Extension font which is only
+% available in medium weight), we let all math versions of these math
+% alphabets refer to medium weight fonts.
+%    \begin{macrocode}
+\DeclareMathAlphabet\cm@equals@alphabet{OT1}{cmr}{m}{n}
+\DeclareMathAlphabet\cm@minus@alphabet{OMS}{cmsy}{m}{n}
+%    \end{macrocode}
+% Note that we use OT1 encoding for the |\cm@equals@alphabet|, even
+% though T1 encoding may be the default for the users system.
+%
+% Also, note that we already have the Computer Modern \texttt{cmsy}
+% family assigned to a symbol font (namely the `symbols' symbol font).
+% However, taking the minus sign directly from this symbol font would
+% make long/extensible arrows come out wrong in the `bold' math
+% version.  (It is perhaps ``overkill'' to allocate a math alphabet
+% just for this purpose?)
+%
+% \begin{macro}{\Relbar}\begin{macro}{\relbar}
+% The long arrows are made using the macros |\Relbar| (for double
+% arrows) and |\relbar| (for single arrows).  The standard \LaTeX\
+% definitions of these macros use the `\texttt{=}' and `\texttt{-}'
+% characters to produce the extension part of the long arrows.  Since
+% we have changed the math codes of these characters (they are now
+% taken from the Euler Fraktur fonts in math mode), we have to
+% redefine the |\Relbar| and |\relbar| macros.
+%    \begin{macrocode}
+\def\Relbar{\mathrel{\cm@equals@alphabet{\mathchar"703D}}}
+\def\cm@minus{{\cm@minus@alphabet{\mathchar"7000}}}
+\def\relbar{\mathrel{\smash\cm@minus}}
+          % \smash, because - has the same height as +
+%    \end{macrocode}
+% \end{macro}\end{macro}
+%
+% \begin{macro}{\leftarrowfill}\begin{macro}{\rightarrowfill}
+% Unfortunately, since the definitions of the ``arrow-filling'' macros
+% (|\leftarrowfill| and |\rightarrowfill|) in standard \LaTeX\ still
+% use explicit minus signs (instead of |\relbar|), we also have to
+% redefine those macros:
+%    \begin{macrocode}
+\def\leftarrowfill
+   {$\m@th\mathord\leftarrow\mkern-6mu%
+     \cleaders\hbox{$\mkern-2mu\cm@minus\mkern-2mu$}\hfill
+     \mkern-6mu\cm@minus$}
+\def\rightarrowfill
+   {$\m@th\cm@minus\mkern-6mu%
+     \cleaders\hbox{$\mkern-2mu\cm@minus\mkern-2mu$}\hfill
+     \mkern-6mu\mathord\rightarrow$}
+%    \end{macrocode}
+% We have defined |\cm@minus| to produce a Computer Modern minus sign
+% of type |\mathord|.  We thereby save a few |\mathord| tokens
+% (compared to the definitions of |\leftarrowfill| and
+% |\rightarrowfill| in standard \LaTeX).
+% \end{macro}\end{macro}
+%
+% There are a few symbols in the original Computer Modern Math Italic
+% fonts that are not present in the Euler fonts.  We simply take them
+% from the CM fonts.
+%    \begin{macrocode}
+\DeclareSymbolFont{cmmigroup}{OML}{cmm}{m}{it}
+\SetSymbolFont{cmmigroup}{bold}{OML}{cmm}{b}{it}
+\DeclareMathAccent\vec          \mathord{cmmigroup}{"7E}
+\DeclareMathSymbol\triangleleft \mathbin{cmmigroup}{"2F}
+\DeclareMathSymbol\triangleright\mathbin{cmmigroup}{"2E}
+\DeclareMathSymbol\star         \mathbin{cmmigroup}{"3F}
+\DeclareMathSymbol\lhook        \mathrel{cmmigroup}{"2C}
+\DeclareMathSymbol\rhook        \mathrel{cmmigroup}{"2D}
+\DeclareMathSymbol\flat         \mathord{cmmigroup}{"5B}
+\DeclareMathSymbol\natural      \mathord{cmmigroup}{"5C}
+\DeclareMathSymbol\sharp        \mathord{cmmigroup}{"5D}
+\DeclareMathSymbol\smile        \mathrel{cmmigroup}{"5E}
+\DeclareMathSymbol\frown        \mathrel{cmmigroup}{"5F}
+%    \end{macrocode}
+% Note that the arrow head of |\vec| is slanted; this looks a bit
+% strange in combination with an upright font such as Euler Roman.
+%
+% Also, note that in the `bold' math version, arrows with hooks will
+% come out wrong (the hooks will be bold, but the arrow heads will be
+% of medium weight).  This can be repaired in a similar way as the
+% long/extensible arrows, but is it worth it to allocate a math
+% alphabet just for this purpose?
+%
+% Finally, Knuth wanted a little extra space before the prime
+% superscript:
+%    \begin{macrocode}
+\begingroup
+   \catcode`\'=\active
+   \gdef'{^\bgroup\mskip2mu\prim@s} % more space before '
+\endgroup
+%    \end{macrocode}
+%
+% Open question: The |\dots| and |\ldots| macros produce dots
+% (periods) from the Euler fonts; the |\ddots| and |\vdots| macros
+% produce dots from the text font; and the |\cdots| macro produces
+% dots from the Computer Modern `symbols' math symbol font.  Should we
+% do something about this?
+%
+% \section{Text fonts in math}\label{text-fonts}
+%
+% The text fonts used in math through math alphabets and the
+% `operators' symbol font should be the same as the fonts used for the
+% main text.  (It is now easy to replace the fonts for the `operators'
+% symbol font, since the uppercase greek letters are now taken from
+% the Euler Roman fonts.)
+%
+% In order to reduce the total number of fonts needed, we shall---if
+% possible---use text fonts in the same encoding for both text and
+% math.  We therefore determine whether T1 encoding has been selected
+% as the default encoding.  We define a switch---|\ifCorkEncoding|---for
+% that purpose.
+%    \begin{macrocode}
+\newif\ifCorkEncoding
+\edef\@tempa{\encodingdefault}\def\@tempb{T1}
+\ifx\@tempa\@tempb
+   \CorkEncodingtrue
+\else
+   \CorkEncodingfalse
+\fi
+%    \end{macrocode}
+% Note that we determine the encoding to use at the time the \euler\
+% package is loaded (\emph{not} at the end of the preamble).  This
+% allows the user to retain OT1 encoding for text fonts used in math
+% (other packages may depend on that) by selecting T1 encoding
+% \emph{after} the \euler\ package has been loaded.
+%
+% We redefine the `operators' symbol font and all math alphabets
+% defined by the \LaTeX\ kernel.  Due to the current implementation of
+% math accents that take their glyphs from text fonts, all text fonts
+% must be used in a common encoding.  The only \LaTeX\ `base' package
+% that defines extra math alphabets is the \texttt{oldlfont} package.
+% However, this package cannot be used together with the \euler\
+% package (it allocates too many symbol fonts).  In other words, the
+% following setup should suffice for most users.
+%    \begin{macrocode}
+\ifCorkEncoding
+  \AtBeginDocument
+    {\DeclareSymbolFont{operators}{T1}\rmdefault\mddefault\updefault
+     \SetSymbolFont{operators}{bold}{T1}\rmdefault\bfdefault\updefault
+     \DeclareMathAlphabet\mathbf{T1}\rmdefault\bfdefault\updefault
+     \DeclareMathAlphabet\mathsf{T1}\sfdefault\mddefault\updefault
+     \DeclareMathAlphabet\mathit{T1}\rmdefault\mddefault\itdefault
+     \DeclareMathAlphabet\mathtt{T1}\ttdefault\mddefault\updefault
+     \SetMathAlphabet\mathsf{bold}{T1}\sfdefault\bfdefault\updefault
+     \SetMathAlphabet\mathit{bold}{T1}\rmdefault\bfdefault\itdefault}
+\else
+  \AtBeginDocument
+    {\DeclareSymbolFont{operators}{OT1}\rmdefault\mddefault\updefault
+     \SetSymbolFont{operators}{bold}{OT1}\rmdefault\bfdefault\updefault
+     \DeclareMathAlphabet\mathbf{OT1}\rmdefault\bfdefault\updefault
+     \DeclareMathAlphabet\mathsf{OT1}\sfdefault\mddefault\updefault
+     \DeclareMathAlphabet\mathit{OT1}\rmdefault\mddefault\itdefault
+     \DeclareMathAlphabet\mathtt{OT1}\ttdefault\mddefault\updefault
+     \SetMathAlphabet\mathsf{bold}{OT1}\sfdefault\bfdefault\updefault
+     \SetMathAlphabet\mathit{bold}{OT1}\rmdefault\bfdefault\itdefault}
+\fi
+%    \end{macrocode}
+% Note that we perform the setup at the end of the preamble (and not
+% while the \euler\ package is being input).  This implies that any
+% changes made to, e.g., |\rmdefault| by a package loaded after the
+% \euler\ package are seen.
+%
+% The standard \LaTeX\ math setup assumes that OT1 encoded text fonts
+% are used in math.  When using T1 encoded fonts, we have to redefine
+% the macros that access accents from the text fonts.
+%    \begin{macrocode}
+\ifCorkEncoding
+   \DeclareMathAccent\grave\mathalpha{operators}{"00}
+   \DeclareMathAccent\acute\mathalpha{operators}{"01}
+   \DeclareMathAccent\tilde\mathalpha{operators}{"03}
+   \DeclareMathAccent\ddot \mathalpha{operators}{"04}
+   \DeclareMathAccent\check\mathalpha{operators}{"07}
+   \DeclareMathAccent\breve\mathalpha{operators}{"08}
+   \DeclareMathAccent\bar  \mathalpha{operators}{"09}
+   \DeclareMathAccent\dot  \mathalpha{operators}{"0A}
+\fi
+%    \end{macrocode}
+%
+% \begin{macro}{\hat}
+% There is one more accent that is normally taken from the `operators'
+% symbol font, namely the |\hat| accent.  This is the only accent
+% provided by the Euler fonts; we shall use this accent by default.
+% (A curious fact is that Knuth devoted a fairly large portion of
+% \texttt{gkpmac.tex} to the construction of a $\phi$ with a hat
+% accent---using the |\widehat| macro).
+%    \begin{macrocode}
+\DeclareMathAccent\hat\mathalpha{EulerFraktur}{"5E}
+%    \end{macrocode}
+% However, some users do not like this |\hat| accent.  They prefer the
+% accent glyph to be taken from the text font (similar to the other
+% accents).
+%    \begin{macrocode}
+\DeclareOption{text-hat-accent}
+   {\ifCorkEncoding
+       \DeclareMathAccent\hat\mathalpha{operators}{"02}%
+    \else
+       \DeclareMathAccent\hat\mathalpha{operators}{"5E}%
+    \fi}
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\hbar}
+% The |\hbar| macro in standard \LaTeX\ is composed of the letter~`h'
+% from the `letters' symbol font and the macron (`bar') accent from
+% the `operators' symbol font.  With the `letters' symbol font now
+% being Euler Roman, the bar is no longer positioned correctly.  We
+% choose the following definition (the \texttt{9mu} in the original
+% definition has been changed to \texttt{8mu}):
+%    \begin{macrocode}
+\ifCorkEncoding
+   \DeclareMathSymbol\euler@hbar\mathord{operators}{"09}
+\else
+   \DeclareMathSymbol\euler@hbar\mathord{operators}{"16}
+\fi
+\def\hbar{{\euler@hbar\mkern-8muh}}
+%    \end{macrocode}
+% \end{macro}
+%
+% \section{Footnotes}\label{footnotes}
+%
+% \begin{macro}{\@makefnmark}
+% Footnote numbers are not math entities, so they should be produced
+% by digits from the text font.  Since footnote markers (whether they
+% are numbers or symbols) are produced in math mode, we can accomplish
+% this by selecting |\operator@font|; this will cause digits to be
+% taken from the `operators' symbol font (which is the same as the
+% font used for text; see previous section).
+%    \begin{macrocode}
+\def\@makefnmark{\hbox{$\operator@font^{\@thefnmark}\m@th$}}
+%    \end{macrocode}
+% \end{macro}
+%
+% \section{Processing options}
+%
+% Finally, we must remember to process the options:
+%    \begin{macrocode}
+\ProcessOptions
+%</package>
+%    \end{macrocode}
+%
+% \Finale
+\endinput
diff --git a/macros/latex/contrib/euler/euler.ins b/macros/latex/contrib/euler/euler.ins
new file mode 100644
index 0000000000..e8f009cf0b
--- /dev/null
+++ b/macros/latex/contrib/euler/euler.ins
@@ -0,0 +1,11 @@
+%%
+%% Copyright (C) 1992 Frank Jensen.  All rights reserved.
+%% Copyright (C) 1993--1995 Frank Jensen and Frank Mittelbach.
+%% All rights reserved.
+%%
+\def\batchfile{euler.ins}
+\input docstrip.tex
+\keepsilent
+\preamble
+\endpreamble
+\generateFile{euler.sty}{f}{\from{euler.dtx}{package}}
diff --git a/macros/latex/contrib/euler/euler.pdf b/macros/latex/contrib/euler/euler.pdf
new file mode 100644
index 0000000000..1a70100674
--- /dev/null
+++ b/macros/latex/contrib/euler/euler.pdf
diff --git a/macros/latex/contrib/euler/legal.txt b/macros/latex/contrib/euler/legal.txt
new file mode 100644
index 0000000000..66b636df09
--- /dev/null
+++ b/macros/latex/contrib/euler/legal.txt
@@ -0,0 +1,13 @@
+The files of this package "euler" may be distributed and/or modified
+under the conditions of the LaTeX Project Public License, either version
+1.2 of this license or (at your option) any later version. The latest
+version of this license is in
+   http://www.latex-project.org/lppl.txt
+and version 1.2 or later is part of all distributions of LaTeX version
+1999/12/01 or later.
+
+The complete listing of files covered by this license is
+  euler.dtx
+  euler.ins
+
+May 2002, Thomas Esser with permission of the copyright owner.