cross-referencing
Possible Duplicate:
Get the title instead of number of a referenced chapter?
Is it possible to use \ref{chap:conclusion} to refer to the actual name of the chapter instead of the chapter counter in LaTeX? So that I can do this:
See the \ref{chap:conclusion} chapter for more information
See the Conclusion chapter for more information
instead of:
See Chapter \ref{chap:conclusion} for more
See Chapter 6 for more
The following minimal working example creates a document with the following structure:
Chapter 1
Section 5
Theorem 5.4
Chapter 7
Section 10
Theorem 10.2
with some dummy text from lipsum. The chapter/section/theorem counters have been set explicitly just for this example.
References using \ref{<label>} return 5.4 and 10.2 regardless of the location where it's called, while \thmref{<label>} conditionally prepends the reference with <chapter>. if the target it not within the chapter. The entire functionality rests on Heiko Oberdiek's (awesome) zref package, and is very much related to Extract Section number from Equation reference. For every label made with \label, a "special" label is created that stores the chapter for that label, since the traditional \label-\ref system only allows for storing two elements: the current label/default and the page. So, chapter numbers as an add-on doesn't easily fit within this realm without some help.
\documentclass{report}
\usepackage{lipsum}% http://ctan.org/pkg/lipsum
\usepackage{amsthm}% http://ctan.org/pkg/amsthm
\usepackage{zref}% http://ctan.org/pkg/zref
\makeatletter
\let\oldlabel\label
\renewcommand{\label}[1]{%
\zref@labelbylist{#1}{special}% Special label
\oldlabel{#1}% Old label
}
\newcounter{splabel}
\zref@newlist{special}% Create a new property list called special
\zref@newprop{chapter}{\arabic{chapter}}% Section property holds \arabic{chapter}
\zref@addprop{special}{chapter}% Add a chapter property to special
\newcommand*{\thmref}[1]{%
\stepcounter{splabel}% Increment local "special label" counter
\zref@labelbylist{#1-\thesplabel}{special}% Create label
\edef\targetchap{\zref@extractdefault{#1}{chapter}{-1}}% Extract target chapter
\edef\sourcechap{\zref@extractdefault{#1-\thesplabel}{chapter}{-1}}% Extract source chapter
\ifnum\targetchap=\sourcechap\else\targetchap.\fi%
\ref{#1}%
}
\newtheorem{theorem}{Theorem}
\renewcommand{\thetheorem}{\arabic{section}.\arabic{theorem}}% Theorem <section>.<theorem>
\@addtoreset{theorem}{chapter}% Theorems reset at start of \chapter
\makeatother
\begin{document}
\chapter{First chapter}\lipsum[1]% Chapter 1
See Theorem~\ref{thm:first} or~\ref{thm:second}.
See Theorem~\thmref{thm:first} or~\thmref{thm:second}.
\setcounter{section}{4}% Just for this example
\section{A section}% Section 5
\setcounter{theorem}{3}% Just for this example
\begin{theorem}\label{thm:first}\lipsum[2]\end{theorem}% Theorem 5.4
\setcounter{chapter}{6}% Just for this example
\chapter{Second chapter}\lipsum[3]% Chapter 7
\setcounter{section}{9}% Just for this example
\section{A section}% Section 10
\setcounter{theorem}{1}% Just for this example
\begin{theorem}\label{thm:second}\lipsum[4]\end{theorem}% Theorem 10.2
\end{document}
The basic idea is the following: Whenever you call \thmref{<label>}, an additional "source" label <label>-# (where # is a counter). The chapter number of the "source" and "target" labels are compared and target chapter is printed conditionally if "source" doesn't equal "target".
Functionality compatible with hyperref is also possible, if needed.
LaTeX provides this cross-referencing scheme out-of-the-box. Place \label{<label>} after a counter that can be referenced (like a chapter, section, subsection, theorem, ...) and use it elsewhere as \ref{<label>}. This will only return the counter number and nothing else:
\documentclass[openany]{book}
\usepackage[paper=a6paper]{geometry}% Just for this example
\usepackage{xparse,nameref}
\NewDocumentCommand{\chapref}{s m}{Chapter~\ref{#2}\IfBooleanF{#1}{ \nameref{#2}}}
\begin{document}
\chapter{Sample 1}\label{ch:first}
This is covered in more detail in \chapref*{ch:second}. Also see~\ref{ch:second}.
\chapter{Sample 2}\label{ch:second}
This is covered in more detail in \chapref{ch:first}. Also see~\ref{ch:first}.
\end{document}
The above example sets the \labels after every \chapter. They're referenced using \ref{<label>}, which clearly just returns the chapter number. However, with the addition of nameref we can grab hold of the chapter title as well, referencing it as \nameref{<label>}. A combination of \ref and \nameref is incorporated in what I defined as \chapref, which translates to Chapter~\ref{<label>} \nameref{<label>}. The latter \nameref is conditional on whether you call \chapref with/without a star *.
The above example can be made fully-functional with hyperref, providing inter-document hyperlinking.
The option [openany] was just so the two chapters fit on subsequent page and is not needed in your document.
Best Answer
You could use the
namerefpackage:produces: