LaTeX forum ⇒ Document Classes ⇒ Create customised references

[TesTT]

Hey,

My document might look like the text below:

Paragraph 1: Lie groups represent the best-developed theory of continuous symmetry of mathematical objects and structures, which makes them indispensable tools for many parts of contemporary mathematics.
...
As discussed in Paragraph 1 we conclude ...

I would like to use references, i.e. something like this:

Code: [Select all] [Expand/Collapse] [Download] (untitled.tex)

Paragraph 1: Lie groups ... mathematics. \createhiddenlabel{mylabel}{Paragraph 1}
...
As discussed in \ref{mylabel} we conclude ... 

Basically I would like to create reference points which are hidden. Is this possible?

[cgnieder]

Are these »Paragraph 1« like paragraphs actually parts that should be indicated by a sectioning command but should not appear in the table of contents? In that case I would probably use a customized \paragraph and set the counters secnumdepth and tocdepth accordingly. Here is an example:

Code: [Select all] [Expand/Collapse] [Download] (untitled.tex)

\documentclass{article}
 
\usepackage{lipsum}% dummy text
 
\setcounter{tocdepth}{3}% subsection level
\setcounter{secnumdepth}{4}% paragraph level
 
\renewcommand{\theparagraph}{Paragraph~\arabic{paragraph}}
\makeatletter
\renewcommand\paragraph{%
   \@startsection
     {paragraph}% name
     {4}% level
     {\z@}% indent
     {3.25ex \@plus1ex \@minus.2ex}% beforeskip
     {-1em}% afterskip, a negative value creates a run-in heading
     {\normalfont\normalsize\noindent}% style: the only value I have changed
}
\makeatother
\begin{document}
 
\tableofcontents
 
\section{Foo Bar}
\paragraph{}\label{par:mylabel} \lipsum[2]
 
In \ref{par:mylabel} we talked about \ldots
 
\end{document}

More fine control over the layout for the \paragraph command would be possible through the titletoc package instead of LaTeX's low level command \@startsection that I have used here.

Regards

[TesTT]

Thanks a lot for that, but basically what I want/need is a simple command like

\CreateAnInvisibleLabel[labelname]{Legendre}

which creates a hidden reference point so that I can access it, e.g.

... as defined in the \ref{labelname} polynomials ...

which gives me

... as defined in the Legendre polynomials ...

[cgnieder]

Well, LaTeX's labels always refer to a counter, i.e. a specific number associated with something like a section or a table caption. The \ref command always only prints the value of the corresponding \the<counter> macro which means you'll get the referenced number. For what you want one would need to define a different label/reference system that writes the words you want to have saved to the aux file and a custom ref command that retrieves it. Maybe this (note that it needs two compilations):

Code: [Select all] [Expand/Collapse] [Download] (untitled.tex)

\documentclass{article}
 
\makeatletter
% #1: id
% #2: word to print
\newcommand*\savelabel[2]{%
   \immediate\write\@auxout{%
     \noexpand\global\noexpand\@namedef{mylabel@#1}{#2}}%
   #2%
}
 
% #1: id
\newcommand*\getlabel[1]{%
   \ifcsname mylabel@#1\endcsname
     \@nameuse{mylabel@#1}%
   \else
     ??%
   \fi
}
\makeatother
 
\begin{document}
 
Before: \getlabel{labelname}
 
Use \savelabel{labelname}{Legendre} in the text
 
After: \getlabel{labelname}
 
\end{document}

Regards

[TesTT]

Thanks a lot! I changed \savelabel to the following so that the label is actually hidden (which is what I wanted).

Code: [Select all] [Expand/Collapse] [Download] (untitled.tex)

\newcommand*\savelabel[2]{%
   \immediate\write\@auxout{%
     \noexpand\global\noexpand\@namedef{mylabel@#1}{#2}}}

[cgnieder]

You can also use this with hyperref, by the way. It has the macros \hypertarget{<label>}{<text>} and \hyperlink{<label>}{<text>} that could be used by themselves or included in the above definition:

Code: [Select all] [Expand/Collapse] [Download] (untitled.tex)

\documentclass{article}
\usepackage{hyperref}
 
\makeatletter
% #1: id
% #2: word to print
\newcommand*\savelabel[2]{%
   \immediate\write\@auxout{%
     \noexpand\global\noexpand\@namedef{mylabel@#1}{#2}}%
   \hypertarget{#1}{}%
}
 
% #1: id
\newcommand*\getlabel[1]{%
   \ifcsname mylabel@#1\endcsname
     \hyperlink{#1}{\@nameuse{mylabel@#1}}%
   \else
     \textbf{??}%
   \fi
}
\makeatother
 
\begin{document}
 
Link before the paragraph: \getlabel{labelname}
 
Some text about \savelabel{labelname}{lorem ipsum} lorem ipsum dolor \ldots
 
Link after the paragraph: \getlabel{labelname} and before the next:
\getlabel{another}
 
Another label\savelabel{another}{another}
 
\end{document}

Regards