Border or frame around figure

Question

I'd like to place a border / frame around my figure.

The figure is a bunch of equations:

\begin{figure}[ht]
    \[ eqn 1 \]

    \[ eqn 2 \]

    \[ eqn 3 \]

    \caption{\label{myfig} My caption.}
\end{figure}

I've tried putting an \fbox{...} and \framebox[\textwidth]{...} around the equations but it doesn't work.

Preferably, I'd like the border to not include the caption.

Any hints are welcome...

---

Related question (though it concerns \includegraphics instead):

• How to add border for an image?

Answer 1

With the package mdframed or framed this is possible

\documentclass{article}
\usepackage{mdframed}
\begin{document}
\begin{figure}[ht]
\begin{mdframed}
    \[ eqn 1 \]

    \[ eqn 2 \]

    \[ eqn 3 \]
\end{mdframed}
    \caption{\label{myfig} My caption.}
\end{figure}
\end{document}

Answer 2

Using memoir (a package for books), you can use the

\begin{framed}
[...]
\end{framed} 

construct. See manual pages 181-183.

Answer 3

IF you don't want to use the memoir documentclass, as is suggested in @Sardathrion's answer, you could use the float package and, in particular, its \floatstyle{boxed} and \restylefloat commands.

A nice feature of the float package is that it provides the H location specifier, as in "I really want this float HERE and nowhere else". Two idiosyncracies of the "boxed" float style are (i) the width of the boxes is that of \textwidth (plus a small fudge factor, so that an object of full \textwidth width fill fit) and (ii) captions of table and figure floats will always be placed below the respective objects. (To change this behavior, one will have to delve into the innards of the code of the float package.)

Aside: if you set tables with the "boxed" float style, you'll definitely want to use as few \hline commands as possible (or, even better, none at all).

\documentclass{article}
\usepackage{float,lipsum}
\floatstyle{boxed}
\restylefloat{table}
\restylefloat{figure}
\begin{document}
\lipsum[1]
\begin{figure}[H]
\centering
ABCDEFG
\caption{A very simple figure}
\end{figure}

\bigskip
\begin{table}[h]
\caption{An equally simple table}
\begin{tabular*}{\textwidth}{@{}l@{\extracolsep{\fill}}rlrlr@{}}
Here & There & Here & There & Here & There 
\end{tabular*}
\end{table}

\lipsum[2]
\end{document}

Answer 4

tcolorbox is another alternative for boxing any kind of contents, even equations.

Following code shows two example, both produce floating objects, the first shows the box around the equation but with an independent caption and the second includes the caption as a title for the box.

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{mathtools}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage[most]{tcolorbox}

\newtcolorbox[blend into=figures]{myfigure}[2][]{float=htb,
title={#2},#1}

\begin{document}
\begin{figure}
\begin{tcolorbox}
\[ \sin^2x+\cos^2x=1\]

\[ 1 + \frac{1}{\tan^2x}=\frac{1}{\sin^2x}\]
\end{tcolorbox}
\caption{Some title for these equations}
\end{figure}

\begin{myfigure}{Some title for these equations}
\[ \sin^2x+\cos^2x=1\]

\[ 1 + \frac{1}{\tan^2x}=\frac{1}{\sin^2x}\]
\end{myfigure}

\end{document}