[Tex/LaTex] What does ‘Label multiply defined’ mean

compilingwarnings

I'm trying to compile this book https://forja.rediris.es/projects/guia-wxmaxima/ I'm using MiKTeX, TeXstudio, and in the build options I have the default compiler pdfLaTeX.
So my question is, why there are a lot of errors that say Label '...' multiply defined?

Best Answer

Because the author hasn't been paying attention to the labels he has used, or to the compile warnings.

The warning means that the same label has been used several times in the same document. For example, he has \label{chap:aritmetica} in three separate chapters, algebra.tex, aritmetica.tex and calculo.tex. This can potentially lead to wrong cross references.

There are two things to do to fix the problem:

Find out which labels are used several times (read the log), and modify all but one of them, so all labels are unique.
Find where those labels are used, and make sure the cross references point to the correct chapter (or whatever it is). To avoid reading the whole thing, use the fact that TeXstudio lets you search in all open documents. Open all the chapter-files in TeXstudio at the same time, go to Edit --> Searching --> Find dialog, and choose Open documents instead of Current document. Then search for the label in questions, for example chap:aritmetica, and see where it has been used in a \ref (or similar command).

(I got a lot of other errors, and the document wouldn't compile at all, but you asked only about the labels.)

Related Solutions

[Tex/LaTex] Multiply defined label warnings when using Subcaption in a Tikz picture

As Martin pointed out, using spy means the picture gets processed several times, which means the label also gets defined several times.

One way to get around this is to keep the spy inside a scope, and place the nodes with the labels after this scope, e.g. using the fit library to place the "label" node on top of the original one.

\documentclass{article} 
\usepackage{tikz} 
\usetikzlibrary{spy,fit} 

\begin{document} 

\begin{figure}\centering 
\begin{tikzpicture}
    \begin{scope}[spy using outlines] 
        \node (testnode) {Testcontent}; 
        \spy[size=1cm,magnification=2] on (0,0) in node at (1.5,1); 
    \end{scope}
    \node [fit=(testnode),inner sep=0pt] {\label{test}};
\end{tikzpicture} 
\caption{Testfigure} 
\end{figure} 

\end{document}

[Tex/LaTex] Texmaker / TeXstudio does not compile XeLaTeX with MiKTeX portable

This is not the optimal response, but it is an answer. You have to edit the path enviromental variable to add, at the end of it, the path to the bin MiKTeX folder (thanks to Speravir for pointing it out). In this case, just add ;E:\LaTeX\MiKTeX\miktex\bin (the semicolon is the separator). A guide to do that is in http://www.computerhope.com/issues/ch000549.htm.

The compiling worked in TeXworks because it sets one folder to look for all the programs, while Texmaker and TeXstudio set the path individually. So, I’m not sure if the fault is in MiKTeX or in the editors just mentioned.

So, what if I wanna use Texmaker from an usb in a computer with no admin rights? Well, just be sure to carry TeXwork (which comes with MiKTeX anyway), then work and save in Texmaker, and then compile from TeXworks.

Best Answer

Related Solutions

[Tex/LaTex] Multiply defined label warnings when using Subcaption in a Tikz picture

[Tex/LaTex] Texmaker / TeXstudio does not compile XeLaTeX with MiKTeX portable

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