# Tabular/array in captions

Could someone explain me why putting tabular/array environments in captions (figure or table) results in errors. Moreover, the error description does not exactly point to the issue, but just reads

Undefined control sequence
\hyper@makecurrent ...


What I would like is: include a matrix in a figure caption.

I know: - that my caption compiles normally as text - that

\begin{figure}
\includegraphics{aaa.EPS}
\caption{$\begin{array}{l} r\\ s\\ t\end{array}$}
\end{figure}


fails to work.

A similar issue happens in tabu environment: I cannot include \footnote{$\begin{array}{l} r\\ s\\ t\end{array}$}, though I can use \footnote{Text} and can use \footnotemark with \footnotetext{$\begin{array}{l} r\\ s\\ t\end{array}$} after \end{tabu}. Still, \footnotemark / \footnotetext messes up footnote numbering and positioning when several of them exist in the same table, so I wish having regular footnotes.

\documentclass{article}
\usepackage{array}
\usepackage{graphicx}

\newsavebox{\foo}
\savebox{\foo}{$\begin{array}{l} r\\ s\\ t\end{array}$}

\pagestyle{empty}

\begin{document}

\begin{figure}
\centering
\includegraphics[scale=.2]{Grenouille}
\caption{\usebox{\foo}}
\end{figure}

\end{document}

• Thanks a lot. Works perfectly in both environments (figure, footnote inside tabu). \newsavebox{\foo} can occur both before and after \begin{document} (even just before where it is used). – Pavel Mostovykh Apr 4 '18 at 16:18
• Before or after works fine for me. You should make a mystake somewhere. Post as an edit your problematic code. – Tarass Apr 4 '18 at 16:21