I have a paper where all equations are numbered, but I want to number equations only if they are actually referred to in the .tex file using \ref{}. How can I make that happen? Alternatively, how can I make all equations that have no \label next to them (because then I know I don't refer to them) not have a number? Do I have to use \nonumber separately for each such equation?
[Tex/LaTex] How to number equations only if they are referred to in the text
cross-referencingequationsnumbering
Related Solutions
[Tex/LaTex] why mathtools does not work for showing only equations which are referred to in the text
I see in your example that you are using eqnarray. This is well-known to be seriously defective, and a number of tools simply do not support it. I see that eqnarray does not show up in the mathtools manual, so I suspect the omission may not be accidental! Use the gather or align environments, as shown in the mathtools manual.
For more detail on the problems of eqnarray see the UK FAQ.
You can use \notag and/or \nonumber from amsmath (or improvised mathtools package):
\documentclass{article}
\usepackage{mathtools,amssymb}
\begin{document}
\begin{align}
x &= y \\\nonumber
x &= 3 \\
y &= 10 \\ \notag
\therefore\ x &\neq y \\
x &= y \\\nonumber
x &= 3 \\
y &= 10 \\ \notag
\therefore\ x &\neq y \\
? &=?
\end{align}
\end{document}
Best Answer
The
mathtoolspackage provides a switchshowonlyrefs. You could use that to achieve that only those equations would be numbered which are referred to in the text.Usage:
or
or set it to false this way if desired.