\documentclass[a4paper]{nlctdoc} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage{lmodern} \usepackage{color} \usepackage{creatdtx} \usepackage{probsoln} \usepackage[colorlinks, bookmarks, hyperindex=false, pdfauthor={Nicola L.C. Talbot}, pdftitle={probsoln: creating problem sheets optionally with solutions}]{hyperref} \doxitem{Option}{option}{package options} \RecordChanges \PageIndex \CheckSum{1822} \newcommand*{\dq}[1]{``#1''} \begin{document} \MakeShortVerb{"} \DeleteShortVerb{\|} \title{probsoln v3.04: creating problem sheets optionally with solutions} \author{Nicola L.C. Talbot\\[10pt] School of Computing Sciences\\ University of East Anglia\\ Norwich. Norfolk\\ NR4 7TJ. United Kingdom.\\ \url{http://theoval.cmp.uea.ac.uk/~nlct/}} \date{2012-08-23} \maketitle \tableofcontents \section{Introduction} The \styfmt{probsoln} package is designed for teachers or lecturers who want to create problem sheets for their students. This package was designed with mathematics problems in mind, but can be used for other subjects as well. The idea is to create a file containing a large number of problems with their solutions which can be read in by \LaTeX, and then select a number of problems to typeset. This means that once the database has been set up, each year you can easily create a new problem sheet that is sufficiently different from the previous year, thus preventing the temptation of current students seeking out the previous year's students, and checking out their answers. There is also an option that can be passed to the package to determine whether or not the solutions should be printed. In this way, one file can either produce the student's version or the teacher's version. \section{Package Options}\label{sec:pkgopt} The following options may be passed to this package: \begin{description} \item[\pkgopt{answers}] Show the answers \item[\pkgopt{noanswers}] Don't show the answers (default) \item[\pkgopt{draft}] Display the label and dataset name when a problem is used \item[\pkgopt{final}] Don't display label and dataset name when a problem is used \item[\pkgopt{usedefaultargs}] Make \ics{thisproblem} use the default arguments supplied in the problem definition. \item[\pkgopt{nousedefaultargs}] Make \ics{thisproblem} prompt for problem arguments (default). \end{description} \section{Verbatim}\label{sec:verbatim} As from version 3.02, problems and solutions may contain verbatim text, but you must use the \iterm{fragile}\texttt{fragile} (or \texttt{fragile=true}) option for the associated environments. Alternatively, if most of your problems contain verbatim, you can globally set this option using: \begin{verbatim} \setkeys{probsoln}{fragile} \end{verbatim} You can switch off this option using \texttt{fragile=false}. The \texttt{fragile} option writes information to a temporary file. This defaults to "\jobname.vrb" but the name may be changed. The extension (".vrb") is given by: \begin{definition}[\DescribeMacro{\ProbSolnFragileExt}] \cs{ProbSolnFragileExt} \end{definition} The base name (\cs{jobname}) is given by: \begin{definition}[\DescribeMacro{\ProbSolnFragileFile}] \cs{ProbSolnFragileFile} \end{definition} \section{Showing and Hiding Solutions}\label{sec:showanswers} In addition to the \pkgopt{answers} and \pkgopt{noanswers} package options, it is also possible to show or suppress the solutions using \begin{definition}[\DescribeMacro{\showanswers}] \cs{showanswers} \end{definition} and \begin{definition}[\DescribeMacro{\hideanswers}] \cs{hideanswers} \end{definition} respectively. The boolean variable \bool{showanswers} determines whether the answers should be displayed. You can use this value with the \sty{ifthen} package to specify different text depending on whether the solutions should be displayed. For example: \begin{verbatim} Assignment 1\ifthenelse{\boolean{showanswers}}{ (Solution Sheet)}{} \end{verbatim} Alternatively you can use \ics{ifshowanswers}\ldots\cs{else}\ldots \cs{fi}: \begin{verbatim} Assignment 1\ifshowanswers\space (Solution Sheet)\fi \end{verbatim} For longer passages, you can use the environments \begin{definition}[\DescribeEnv{onlyproblem}] \cs{begin}\marg{onlyproblem}\oarg{option} \end{definition} and \begin{definition}[\DescribeEnv{onlysolution}] \cs{begin}\marg{onlysolution}\oarg{option} \end{definition} For example: \begin{verbatim} \begin{onlyproblem}% What is the derivative of $f(x) = x^2$? \end{onlyproblem}% \begin{onlysolution}% $f'(x) = 2x$ \end{onlysolution} \end{verbatim} The above will only display the question if \bool{showanswers} is false and will only display the solution if \bool{showanswers} is true. If you want the question to appear in the answer sheet as well as the solution, then don't put the question in the \env{onlyproblem} environment: \begin{verbatim} What is the derivative of $f(x) = x^2$? \begin{onlysolution}% Solution: $f'(x) = 2x$ \end{onlysolution} \end{verbatim} \begin{important} If you want to include verbatim text in the body of \env{onlyproblem} or \env{onlysolution}, you need to specify \texttt{fragile} in the optional argument of the environment. (See \sectionref{sec:verbatim} for further details.) \end{important} If you use \envfmt{onlysolution} within the \env{defproblem} environment, the problem will be tagged as having a solution and will be added to the list used by \ics{foreachsolution}. The optional argument of \envfmt{onlysolution} (and \env{onlyproblem}) is inherited from the parent \env{defproblem} setting. \section{General Formatting Commands}\label{sec:formatting} The commands and environments described in this section are provided to assist formatting problems and their solutions. \begin{definition}[\DescribeEnv{solution}] \verb|\begin{solution}|\meta{text}\verb|\end{solution}| \end{definition} By default, this is equivalent to \begin{display} \verb|\par\noindent\textbf{\solutionname}: |\meta{text} \end{display} where \DescribeMacro{\solutionname}\cs{solutionname} defaults to \dq{\solutionname}. Note that you must place the \env{solution} environment inside the \envfmt{onlysolution} environment or between \ics{ifshowanswers}\ldots\cs{fi} to ensure that it is suppressed when the solutions are not wanted. (See \sectionref{sec:showanswers}.) Note that the \styfmt{probsoln} package will only define the \env{solution} environment if it is not already defined. \begin{definition}[\DescribeEnv{textenum}] \verb|\begin{textenum}|\ldots\verb|\end{textenum}| \end{definition} The \envfmt{textenum} environment is like the \env{enumerate} environment but is in-line. It uses the same counter that the \envfmt{enumerate} environment would use at that level so the question can be compact but the answer can use \envfmt{enumerate} instead. For example: \begin{verbatim} \begin{onlyproblem}% Differentiate the following: \begin{textenum} \item $f(x)=2^x$; \item $f(x)=\cot(x)$ \end{textenum} \end{onlyproblem} \begin{onlysolution} \begin{enumerate} \item \begin{align*} f(x) &= 2^x = \exp(\ln(x^2)) =\exp(2\ln(x))\\ f'(x) &= \exp(2\ln(x))\times \frac{2}{x}\\ &= f(x)\frac{2}{x} \end{align*} \item \begin{align*} f(x) &= \cot(x) = (\tan(x))^{-2}\\ f'(x) &= -(\tan(x))^{-2}\times\sec^2(x)\\ &=-\csc^2x \end{align*} \end{enumerate} \end{onlysolution} \end{verbatim} In this example, the items in the question are brief, so an \env{enumerate} environment would result in a lot of unnecessary white space, but the answers require more space, so an \envfmt{enumerate} environment is more appropriate. Since the \envfmt{textenum} environment uses the same counters as the \envfmt{enumerate} environment, the question and answer sheets use consistent labelling. Note that there are other packages available on CTAN that you can use to create in-line lists. Check the \urlfootref{http://www.tex.ac.uk/tex-archive/help/Catalogue/bytopic.html\#enumeration}{TeX Catalogue} for further details. \DescribeMacro{\correctitem}\DescribeMacro{\incorrectitem} \begin{definition} \cs{correctitem}\\ \cs{incorrectitem} \end{definition} You can use the commands \cs{correctitem} and \cs{incorrectitem} in place of \ics{item}. If the solutions are suppressed, these commands behave in the same way as \cs{item}, otherwise they format the item label using one of the commands: \DescribeMacro{\correctitemformat}\DescribeMacro{\incorrectitemformat} \begin{definition} \cs{correctitemformat}\marg{label}\\ \cs{incorrectitemformat}\marg{label} \end{definition} For example: \begin{verbatim} Under which of the following functions does $S=\{a_1,a_2\}$ become a probability space? \begin{enumerate} \incorrectitem $P(a_1)=\frac{1}{3}$, $P(a_2)=\frac{1}{2}$ \correctitem $P(a_1)=\frac{3}{4}$, $P(a_2)=\frac{1}{4}$ \correctitem $P(a_1)=1$, $P(a_2)=0$ \incorrectitem $P(a_1)=\frac{5}{4}$, $P(a_2)=-\frac{1}{4}$ \end{enumerate} \end{verbatim} The default definition of \cs{correctitemformat} puts a frame around the label. \section{Defining a Problem}\label{sec:defproblem} It is possible to construct a problem sheet with solutions using the commands described in the previous sections, however it is also possible to define a set of problems for later use. In this way you can create an external file containing many problems some or all of which can be loaded and used in a document. The \styfmt{probsoln} package has a default data set labelled \dq{default} in which you can store problems. Alternatively, you can create multiple data sets. You can then iterate through each problem in a problem set. You can use a previously defined problem more than once, which means that by judicious use of \env{onlyproblem}, \env{onlysolution} or the \bool{showanswers} boolean variable in conjunction with \ics{showanswers} and \ics{hideanswers}, you can print the solutions in a different location to the questions (for example in an appendix). \begin{definition}[\DescribeEnv{defproblem}] \verb|\begin{defproblem}|\oarg{n}\oarg{default args}\marg{label}\oarg{option}\newline \meta{definition}\newline \verb|\end{defproblem}| \end{definition} This defines the problem whose label is given by \meta{label}. The label must be unique for a given data set and should not contain active characters or a comma. (Active characters include the special characters such as \$ and \&, but some packages may make other symbols active, such as the colon (:) character. For example, the \sty{ngerman} and \sty{babel} packages make certain punctuation active. Check the relevant package documentation for details.) \begin{important} The final optional argument \meta{option} may be \texttt{fragile} to indicate that the problem contains verbatim text. Any occurrences of \env{onlyproblem} or \env{onlysolution} contained within \envfmt{defproblem} are inherited from \envfmt{defproblem}. (See \sectionref{sec:verbatim} for further details.) \end{important} If \env{defproblem} occurs in the document or is included via \ics{input} or \ics{include}, then the problem will be added to the default data set. If \envfmt{defproblem} occurs in an external file that is loaded using one of the commands defined in \sectionref{sec:load} then the problem will be added to the specified data set. The contents of the \env{defproblem} environment should be the text that defines the problem. This may include any of the commands defined in \sectionref{sec:showanswers} and \sectionref{sec:formatting}. The problem may optionally take \meta{n} arguments (where \meta{n} is from 0 to 9). The arguments can be referenced in the definition via \texttt{\#1},\ldots,\texttt{\#9}. If \meta{n} is omitted then the problem doesn't take any arguments. The following example defines a problem with one argument: \begin{verbatim} \begin{defproblem}[1]{diffsin} Differentiate $f(x)=\sin(#1x)$. \begin{onlysolution}% \begin{solution} $f'(x) = #1\cos(#1x)$ \end{solution} \end{onlysolution} \end{defproblem} \end{verbatim} The second optional argument \meta{default args} supplies default problem arguments that will automatically be used within \ics{thisproblem} when used in \ics{foreachproblem} in conjunction with the package option \pkgopt{usedefaultargs}. (See \sectionref{sec:foreach}.) For example: \begin{verbatim} \begin{defproblem}[1][{2}]{diffsin} Differentiate $f(x)=\sin(#1x)$. \begin{onlysolution}% \begin{solution} $f'(x) = #1\cos(#1x)$ \end{solution} \end{onlysolution} \end{defproblem} \end{verbatim} \begin{definition}[\DescribeMacro{\newproblem}] \cs{newproblem}\oarg{n}\oarg{default args}\marg{label}\marg{problem}\marg{solution} \end{definition} This is a shortcut command for: \begin{ttfamily}\obeylines \cs{begin}\{defproblem\}\oarg{n}\oarg{default args}\marg{label}\% \meta{problem}\% \cs{begin}\{onlysolution\}\% \cs{begin}\{solution\}\% \meta{solution}\% \cs{end}\{solution\}\% \cs{end}\{onlysolution\}\% \cs{end}\{defproblem\} \end{ttfamily} For example: \begin{verbatim} \newproblem[1]{diffsin}{% \(f(x) = \sin(#1x)\) }% {% \(f'(x) = #1\cos(#1x)\) } \end{verbatim} is equivalent to \begin{verbatim} \begin{defproblem}[1]{diffcos}% \(f(x) = \cos(#1x)\) \begin{onlysolution}% \begin{solution}% \(f'(x) = -#1\sin(#1x)\) \end{solution}% \end{onlysolution}% \end{defproblem} \end{verbatim} (In this example, the argument will need to be a positive number to avoid a double minus in the answer. If you want to perform floating point arithmetic on the arguments, then try the \sty{fp} or \sty{pgfmath} packages.) Alternatively, if you want to supply default arguments to use when iterating through problems with \ics{foreachproblem}: \begin{verbatim} \newproblem[1][{3}]{diffsin}{% \(f(x) = \sin(#1x)\) }% {% \(f'(x) = #1\cos(#1x)\) } \end{verbatim} \begin{definition}[\DescribeMacro{\newproblem*}] \cs{newproblem*}\oarg{n}\oarg{default args}\marg{label}\marg{definition} \end{definition} This is a shortcut for: \begin{ttfamily}\obeylines \cs{begin}\{defproblem\}\oarg{n}\oarg{default args}\marg{label}\% \meta{definition}\% \cs{end}\{defproblem\} \end{ttfamily} \begin{important} Note that you can't use verbatim text with \cs{newproblem} or \cs{newproblem*}. Use the \env{defproblem} environment instead with the \texttt{fragile option}. \end{important} \section{Using a Problem}\label{sec:useproblem} Once you have defined a problem using \env{defproblem} or \ics{newproblem} (see \sectionref{sec:defproblem}), you can later display the problem using: \begin{definition}[\DescribeMacro{\useproblem}] \cs{useproblem}\oarg{data set}\marg{label}\marg{arg$_1$}\ldots \marg{arg$_N$} \end{definition} where \meta{data set} is the name of the data set that contains the problem (the default data set is used if omitted), \meta{label} is the label identifying the required problem and \meta{arg$_1$}, \ldots, \meta{arg$_N$} are the arguments to pass to the problem, if the problem was defined to have arguments (where $N$ is the number of arguments specified when the problem was defined). For example, in the previous section the problem \texttt{diffcos} was defined to have one argument, so it can be used as follows: \begin{verbatim} \useproblem{diffcos}{3} \end{verbatim} This will be equivalent to: \begin{verbatim} \(f(x) = \cos(3x)\) \begin{onlysolution}% \begin{solution}% \(f'(x) = -3\sin(3x)\) \end{solution}% \end{onlysolution}% \end{verbatim} \section{Loading Problems From External Files}\label{sec:load} You can store all your problem definitions (see \sectionref{sec:defproblem}) in an external file. These problems can all be appended to the default data set by including the file via \ics{input} or they can be appended to other data sets using one of the commands described below. Once you have loaded all the required problems, you can iterate through the data sets using the commands described in \sectionref{sec:foreach}. Note that the commands below will create a new data set, if the named data set doesn't exist. \begin{definition}[\DescribeMacro{\loadallproblems}] \cs{loadallproblems}\oarg{data set}\marg{filename} \end{definition} This will load all problems defined in \meta{filename} and append them to the specified data set, in the order in which they are defined in the file. If \meta{data set} is omitted, the default data set will be used. If \meta{data set} doesn't exist, it will be created. \begin{definition}[\DescribeMacro{\loadselectedproblems}] \cs{loadselectedproblems}\oarg{data set}\marg{labels}\marg{filename} \end{definition} This is like \cs{loadallproblems}, but only those problems whose label is listed in the comma-separated list \meta{labels} are loaded. For example, if I have some problems defined in the file \texttt{derivatives.tex}, then \begin{verbatim} \loadselectedproblems{diffsin,diffcos}{derivatives} \end{verbatim} will only load the problems whose labels are \texttt{diffsin} and \texttt{diffcos}, respectively. All the other problems in the file will remain undefined. \begin{definition}[\DescribeMacro{\loadexceptproblems}] \cs{loadexceptproblems}\oarg{data set}\marg{exception list}\marg{filename} \end{definition} This is the reverse of \cs{loadselectedproblems}. This loads all problems except those whose labels are listed in \meta{exception list}. \begin{definition}[\DescribeMacro{\loadrandomproblems}] \cs{loadrandomproblems}\oarg{data set}\marg{n}\marg{filename} \end{definition} This randomly loads \meta{n} problems from \meta{filename} and adds them to the given data set. If \meta{data set} is omitted, the default data set is assumed. Note that the problems will be added to the data set in a random order, not in the order in which they were defined. There must be at least \meta{n} problems defined in \meta{filename}. \begin{definition}[\DescribeMacro{\loadrandomexcept}] \cs{loadrandomexcept}\oarg{data set}\marg{n}\marg{filename}\marg{exception list} \end{definition} This is similar to \cs{loadrandomproblems} except that it won't load those problems whose labels are listed in \meta{exception list}. \textbf{If you want to automatically exclude problems included in previous documents, see \sectionref{sec:exprev}.} Note that the random number generator has been modified in version 3.01 in order to fix a bug. If you want to ensure that your random numbers are compatible with earlier versions, you can switch to the old generator using \begin{definition}[\DescribeMacro{\PSNuseoldrandom}] \cs{PSNuseoldrandom} \end{definition} \begin{important} It is generally not a good idea to place anything in \meta{filename} that is not inside the body of \env{defproblem} or in the arguments to \ics{newproblem} or \ics{newproblem*}. All the commands in this section input the external file within a local scope, so command definitions would need to be made global to have any effect. In addition, \cs{loadrandomproblems} has to load each file twice, which means that anything outside a problem definition will be parsed twice. \end{important} \subsection{Randomly Selecting Problems Not Selected in Previous Documents} \label{sec:exprev} Suppose you have a large set of questions that you want to randomly select for assignments and exams. The chances are, you don't want to include questions that have been previously set for, say, the last three years. That is, you don't want to select questions the students may already have seen. As from version 3.03, you can now do this. The \sty{probsoln} package defaults to the UK academic year, which starts in September. If this isn't appropriate, you can change it using: \begin{definition}[\DescribeMacro{\SetStartMonth}] \cs{SetStartMonth}\marg{n} \end{definition} where \meta{n} is the number of the month. (1 = January, 2 = February, etc.) The \emph{start year} is the calender year in effect when the academic year started. For example, if this is the academic year 2011/12, then the start year is 2011. This is automatically set to the start of the current academic year. It is also updated when \cs{SetStartMonth} is used.\footnote{So don't use \cs{SetStartMonth} after \cs{SetStartYear}.} If you want to set it to a specific year, you can use: \begin{definition}[\DescribeMacro{\SetStartYear}] \cs{SetStartYear}\marg{year} \end{definition} For example: \verb|\SetStartYear{2008}| indicates the academic year 2008/9. There are two files concerned with previously used labels. They are: \begin{description} \item[The previously used labels file] This keeps track of all problems used in previous years, as well as problems used by other documents that have this as their previously used labels file, and it contains the problem labels from the last run of the current document. \item[The current used labels file] This defaults to \cs{jobname}\texttt{.prb}, but the name can be changed using: \begin{definition}[\DescribeMacro{\SetUsedFileName}] \cs{SetUsedFileName}\marg{name} \end{definition} This file keeps track of all the labels used in the current document from the previous \LaTeX\ run. Note that if you want to delete this file, first clear it using \begin{definition}[\DescribeMacro{\ClearUsedFile}] \cs{ClearUsedFile}\marg{file} \end{definition} in place of \cs{ExcludePreviousFile}\marg{file}, described below. The argument \meta{file} is the previously used labels file described above. \cs{ClearUsedFile} will remove all labels in the current used labels file from the previously used labels file and clear the current used labels file. Once this file is empty, it may then be deleted. \end{description} Before loading randomly selected problems, first specify the previously used labels file with the command: \begin{definition}[\DescribeMacro{\ExcludePreviousFile}] \cs{ExcludePreviousFile}\oarg{number of years}\marg{file name} \end{definition} where \meta{file name} is the name of the previously used file. The optional argument \meta{number of years} specifies the year cut-off. This defaults to 3, which means that only those labels used this year or the previous 2 years will be kept. Any problems used before then may be reused. Suppose I'm lecturing a first year undergraduate mathematics course (designated, say, mth101). I want to set assignments on each topic and an exam at the end of the year (as well as a resit or second sitting paper). I've got databases with problems for each topic, but the first and second sitting exams mustn't include any of the problems used in the assignments or any problems used in assignments or exams for the previous two academic years. I'm going to arrange my directory structure as follows: \begin{itemize} \item \texttt{mth101/} \begin{itemize} \item \texttt{assignment1/} (differentiation) \begin{itemize} \item \texttt{assignment1.tex} \end{itemize} \item \texttt{assignment2/} (probability spaces) \begin{itemize} \item \texttt{assignment2.tex} \end{itemize} \item \texttt{assignment3/} (linear algebra) \begin{itemize} \item \texttt{assignment3.tex} \end{itemize} \item \texttt{exams/} \begin{itemize} \item \texttt{exam.tex} (first sitting) \item \texttt{resit.tex} (second sitting) \end{itemize} \item \texttt{databases/} \begin{itemize} \item \texttt{differentiation.tex} \item \texttt{probabilityspaces.tex} \item \texttt{linearalgebra.tex} \end{itemize} \item \texttt{previouslabels.tex} (created by \sty{probsoln}) \end{itemize} \end{itemize} \section{Iterating Through Datasets}\label{sec:foreach} Once you have defined all your problems for a given data set, you can use an individual problem with \ics{useproblem} (see \sectionref{sec:useproblem}) but it is more likely that you will want to iterate through all the problems so that you don't need to remember the labels of all the problems you have defined. \begin{definition}[\DescribeMacro{\foreachproblem}] \cs{foreachproblem}\oarg{data set}\marg{body} \end{definition} This does \meta{body} for each problem in the given data set. If \meta{data set} is omitted, the default data set is used. Within \meta{body} you can use \begin{definition}[\DescribeMacro{\thisproblem}] \cs{thisproblem} \end{definition} to use the current problem and \begin{definition}[\DescribeMacro{\thisproblemlabel}] \cs{thisproblemlabel} \end{definition} to access the current label. If the problem requires arguments, and no default arguments were supplied in the problem definition or the package option \pkgopt{usedefaultargs} was not used, then you will be prompted for arguments, so if you want to use this approach you will need to use \LaTeX\ in interactive mode. If you do provide arguments, they will be stored in the event that you need to iterate through the data set again. The arguments will be included in \cs{thisproblem}, so you only need to use \cs{thisproblem} without having to specify \ics{useproblem}. For example, to iterate through all problems in the default data set: \begin{verbatim} \begin{enumerate} \foreachproblem{\item\thisproblem} \end{enumerate} \end{verbatim} \begin{definition}[\DescribeMacro{\foreachsolution}] \cs{foreachsolution}\oarg{data set}\marg{body} \end{definition} This is equivalent to \cs{foreachsolution}, but only iterates through problems that contain the \env{onlysolution} environment. Note that you still need to use \ics{showanswers} or the \pkgopt{answers} package option for the contents of the \env{onlysolution} environment to appear. \begin{definition}[\DescribeMacro{\foreachdataset}] \cs{foreachdataset}\marg{cmd}\marg{body} \end{definition} This does \meta{body} for each of the defined data sets. Within \meta{body}, \meta{cmd} will be set to the name of the current data set. For example, to display all problems in all data sets: \begin{verbatim} \begin{enumerate} \foreachdataset{\thisdataset}{% \foreachproblem[\thisdataset]{\item\thisproblem}} \end{enumerate} \end{verbatim} Suppose I have two external files called \texttt{derivatives.tex} and \texttt{probspaces.tex} which define problems using both \env{onlyproblem} and \env{onlysolution} for example: \begin{verbatim} \begin{defproblem}{cosxsqsinx}% \begin{onlyproblem}% $y = \cos(x^2)\sin x$.% \end{onlyproblem}% \begin{onlysolution}% \[\frac{dy}{dx} = -\sin(x^2)2x\sin x + \cos(x^2)\cos x\] \end{onlysolution}% \end{defproblem} \end{verbatim} I can write a document that creates two data sets, one for the derivative problems and one for the problems about probability spaces. I can then use \ics{hideanswers} and iterate through the require data set to produce the problems. Later, I can use \ics{showanswers} and iterate over all problems defined in both data sets to produce the chapter containing all the answers. When displaying the questions, I have taken advantage of the fact that I can cross-reference items within an \env{enumerate} environment, and redefined \ics{theenumi} to label the questions according to the chapter. The cross-reference label is constructed from the problem label and is referenced in the answer section to ensure that the answers have the same label as the questions. \begin{verbatim} \documentclass{report} \usepackage{probsoln} \begin{document} \hideanswers \chapter{Differentiation} % randomly select 25 problems from derivatives.tex and add to % the data set called 'deriv' \loadrandomproblems[deriv]{25}{derivatives} % Display the problems \renewcommand{\theenumi}{\thechapter.\arabic{enumi}} \begin{enumerate} \foreachproblem[deriv]{\item\label{prob:\thisproblemlabel}\thisproblem} \end{enumerate} % You may need to change \theenumi back here \chapter{Probability Spaces} % randomly select 25 problems from probspaces.tex and add to % the data set called 'spaces' \loadrandomproblems[spaces]{25}{probspaces} % Display the problems \renewcommand{\theenumi}{\thechapter.\arabic{enumi}} \begin{enumerate} \foreachproblem[spaces]{\item\label{prob:\thisproblemlabel}\thisproblem} \end{enumerate} % You may need to change \theenumi back here \appendix \chapter{Solutions} \showanswers \begin{itemize} \foreachdataset{\thisdataset}{% \foreachproblem[\thisdataset]{\item[\ref{prob:\thisproblemlabel}]\thisproblem} } \end{itemize} \end{document} \end{verbatim} \section{Random Number Generator}\label{sec:random} This package provides a pseudo-random number generator that is used by \ics{loadrandomproblems}. As noted earlier the random number generator has been modified in version 3.01 in order to fix a bug. If you want to ensure that your random numbers are compatible with earlier versions, you can switch to the old generator using \begin{definition}[\DescribeMacro{\PSNuseoldrandom}] \cs{PSNuseoldrandom} \end{definition} \begin{definition}[\DescribeMacro{\PSNrandseed}] \cs{PSNrandseed}\marg{n} \end{definition} This sets the seed to \meta{n} which must be a non-zero integer. For example, to generate a different set of random numbers every time you \LaTeX\ your document,\footnote{assuming you leave at least a minute between runs.} put the following in your preamble: \begin{verbatim} \PSNrandseed{\time} \end{verbatim} or to generate a different set of random numbers every year you \LaTeX\ your document: \begin{verbatim} \PSNrandseed{\year} \end{verbatim} \begin{definition}[\DescribeMacro{\PSNgetrandseed}] \cs{PSNgetrandseed}\marg{register} \end{definition} This stores the current seed in the count register specified by \meta{register}. For example: \begin{verbatim} \newcount\myseed \PSNgetrandseed{\myseed} \end{verbatim} \begin{definition}[\DescribeMacro{\PSNrandom}] \cs{PSNrandom}\marg{register}\marg{n} \end{definition} Generates a random integer from 1 to \meta{n} and stores in the count register specified by \meta{register}. For example, the following generates an integer from 1 to 10 and stores it in the register \cs{myreg}: \begin{verbatim} \newcount\myreg \PSNrandom{\myreg}{10} \end{verbatim} \begin{definition}[\DescribeMacro{\random}] \cs{random}\marg{counter}\marg{min}\marg{max} \end{definition} Generates a random integer from \meta{min} to \meta{max} and stores in the given counter. For example, the following generates a random number between 3 and 8 (inclusive) and stores it in the counter \texttt{myrand}. \begin{verbatim} \newcounter{myrand} \random{myrand}{3}{8} \end{verbatim} \begin{definition}[\DescribeMacro{\doforrandN}] \cs{doforrandN}\marg{n}\marg{cmd}\marg{list}\marg{text} \end{definition} Randomly selects \meta{n} values from the comma-separated list given by \meta{list} and iterates through this subset. On each iteration it sets \meta{cmd} to the current value and does \meta{text}. For example, the following will load a randomly selected problem from two of the listed files (where \texttt{file1.tex}, \texttt{file2.tex} and \texttt{file3.tex} are files containing at least one problem): \begin{verbatim} \doforrandN{2}{\thisfile}{file1,file2,file3}{% \loadrandomproblems{1}{\thisfile}} \end{verbatim} \section{Compatibility With Versions Prior to 3.0} Version 3.0 of the \sty{probsoln} package completely changed the structure of the package, but the commands described in this section have been provided to maintain compatibility with earlier versions. The only problems that are likely to occur are those where commands are contained within groups. This will effect any commands that are contained in external files that are outside of the arguments to \ics{newproblem} and \ics{newproblem*}. However, since the external files had to be parsed twice in order to load the problems, this shouldn't be an issue as adding anything other than problem definitions in those files would be problematic anyway. The other likely difference is where the random generator is used in a group. This includes commands such as \ics{selectrandomly}. For example, if your document contained something like: \begin{verbatim} \begin{enumerate} \selectrandomly{file1}{8} \item Solve the following: \begin{enumerate} \selectrandomly{file2}{4} \end{enumerate} \selectrandomly{file3}{2} \end{enumerate} \end{verbatim} Then using versions prior to v3.0 will produce a different set of random numbers since the second \cs{selectrandomly} is in a different level of grouping. If you want to ensure that the document produces exactly the same random set with the new version as with the old version, you will need to get and set the random number seed. For example, the above would need to be modified so that it becomes: \begin{verbatim} \begin{enumerate} \selectrandomly{file1}{8} \item Solve the following: \newcount\oldseed \PSNgetrandseed{\oldseed} \begin{enumerate} \selectrandomly{file2}{4} \end{enumerate} \PSNrandseed{\oldseed} \selectrandomly{file3}{2} \end{enumerate} \end{verbatim} \begin{definition}[\DescribeMacro{\selectrandomly}] \cs{selectrandomly}\marg{filename}\marg{n} \end{definition} This is now equivalent to: \begin{ttfamily}\obeylines \{\cs{loadrandomproblems}\oarg{filename}\marg{n}\marg{filename}\}\% \cs{foreachproblem}\oarg{filename}\{\cs{PSNitem}\cs{thisproblem}\cs{endPSNitem}\} \end{ttfamily} \begin{definition}[\DescribeMacro{\selectallproblems}] \cs{selectallproblems}\marg{filename} \end{definition} This is now equivalent to: \begin{ttfamily}\obeylines \{\cs{loadallproblems}\oarg{filename}\marg{filename}\}\% \cs{foreachproblem}\oarg{filename}\{\cs{PSNitem}\cs{thisproblem}\cs{endPSNitem}\} \end{ttfamily} Note that in both the above cases, a new data set is created with the same name as the file name. \StopEventually{\clearpage\phantomsection\addcontentsline{toc}{section}{Index}\PrintIndex} \end{document}