Use a symbol in a formula that's been defined over elsewhere

Question

In my document preamble, I'm using:

\usepackage{fancyvrb}
\DefineShortVerb{\|}

It means I can indicate that things are to be rendered as code with |This_is_monospaced|, but now I'm trying to use vertical bars to represent magnitude in a formula, as such: $|V|$ (typeset with amsmath)

What I'm currently getting is a verbatim environment within my formula.

Is there a way of temporarily disabling the monospacing behaviour so my formula still renders normally?

Answer 1

You can load amsmath

\usepackage{amsmath}

and then use

$\lvert V\rvert$

Another option is to use \UndefineShortVerb:

\documentclass{article}
\usepackage{amsmath}
\usepackage{fancyvrb}
\DefineShortVerb{\|}

\begin{document}

$\lvert V\rvert$

\UndefineShortVerb{\|}
$|V|$
\DefineShortVerb{\|}

\end{document}

As Andrew Swann mentions in his comment, in general it is preferable to use \lvert...\rvert instead of just |...|.