Redefine eqnarray environment to render its content in red

Question

For (copy) editing purposes I'd like to redefine the eqnarray envinronment to render its content in red (or any other colour). How can I do it?

Edit. I'll use this trick to better spot and (eventually) change the instances of eqnarray.

It would be better to explain why you want it. I remember about your job, other people might not. — egreg, Jun 19 '20 at 21:07

score 5 · Accepted Answer · answered Jun 19 '20 at 20:35

5

I think etoolbox can do the trick

\documentclass{article}
\usepackage{xcolor}
\usepackage{etoolbox}
\AtBeginEnvironment{eqnarray*}{\color{red}}
\begin{document}
\begin{eqnarray}
  \dot x &=& v \
  \dot v &=& F(x)
\end{eqnarray}
\end{document}

answered Jun 19 '20 at 20:35

Denys Potapov

962

Exactly what I needed! Thank you! – Gabriele Jun 19 '20 at 20:48

score 1 · Answer 2 · answered Jun 19 '20 at 20:45

1

Of course, one shouldn't use eqnarray. A similar approach to the suggestion by @Denys Potapov works with the align environment from the amsmath package. Note that the equation numbers will be coloured with align, whereas I don't think they will with eqnarray.

\documentclass{article}
\usepackage{amsmath}
\usepackage{color}
\let\oldalign\align
\def\align{%
\color{red}\oldalign}
\begin{document}
abc
\begin{align}
a &= b \\
  &= c
\end{align}
def
\end{document}

answered Jun 19 '20 at 20:45

Ian Thompson

43,767

I guess that the OP's aim is to visually find the instances of eqnarray so to be able to change them in the source. – egreg Jun 19 '20 at 21:02
@egreg --- I fully support any effort to find and remove instances of eqnarray. – Ian Thompson Jun 19 '20 at 21:04
1

The OP explained time ago that he's in charge of copy editing, so my guess. – egreg Jun 19 '20 at 21:06
@egreg Indeed i'll use this trick to better spot and (eventually) change the instances of eqnarray ;-) – Gabriele Jun 19 '20 at 22:15

Redefine eqnarray environment to render its content in red

2 Answers2