Equations and Equation Numbers within a Box

Question

I use the code below to make a box around equations. It puts the equations numbers outside the box, however I would like to have the equation numbers within the box.

How can I alter my code to do this? Thanks in advance.

\documentclass[11pt]{report}

    \usepackage{empheq}


    \newcommand*\widefbox[1]{\fbox{\hspace{2em}#1\hspace{2em}}}

    \begin{document}
    \begin{empheq}[box=\widefbox]{align}
    & a = b +c \\
    & d = e+f
    \end{empheq}
    \end{document}

(So: I would like to have the ''(1)'' and ''(2)'' within the box.)

possible duplicate: Boxed equation with equation number inside — barbara beeton, Sep 17 '15 at 13:16

score 6 · Accepted Answer · answered Sep 17 '15 at 12:02

For a change, use tcolorbox:

\documentclass[11pt]{report}

\usepackage[most]{tcolorbox}
\tcbset{myformula/.style={colback=white, %yellow!10!white,
    colframe=black, %red!50!black,
    top=0pt,bottom=0pt,left=0pt,right=0pt,
    boxsep=0pt,
    arc=0pt,
    outer arc=0pt,
}}

\begin{document}
\begin{tcolorbox}[ams align,myformula]
& a = b +c \\
& d = e+f
\end{tcolorbox}
\end{document}

score 3 · Answer 2 · answered Sep 17 '15 at 12:13

Before I know for tcolorbox I use the following solution:

\documentclass{article}
    \usepackage{empheq}

    \newlength\fsep
    \setlength\fsep{2\fboxsep+2\fboxrule}
    \newsavebox\widebox
\newenvironment{mathbox}
    {\par\vskip\fsep\noindent%
     \begin{lrbox}{\widebox}%
     \begin{minipage}{\textwidth-\fsep}%
    }{\vskip\fsep\end{minipage}\end{lrbox}
      \framebox{\usebox\widebox}%
     }

    \begin{document}
\begin{mathbox}
    \begin{align}
a & = b +c \\
d & = e+f
    \end{align}
\end{mathbox}
    \end{document}

which gives:

Bernard · Answer 3 · 2015-09-17T19:30:38.793

Here is a simple solution with the framed package. I define a myframedeq environment, which has one optional argument, the width of the frame (default: \textwidth). One could in the same way define a shadedeq environment which would put wrap the math environment is a coloured box, with a coloured background.

\documentclass[11pt]{report}
\usepackage[showframe]{geometry}
\usepackage{empheq}
\usepackage{xcolor, framed}

\newcommand*\widefbox[1]{\fbox{\hspace{2em}#1\hspace{2em}}}
\newenvironment{myframedeq}[1][\linewidth]{\FrameSep=4pt\abovedisplayskip=0pt\belowdisplayskip=0pt
\framed\hsize=#1\leftskip=\dimexpr(\textwidth-#1)/2\relax}
{\endframed}

\begin{document}
\begin{empheq}[box=\widefbox]{align}
  & a = b +c \\
  & d = e+f
\end{empheq}
Text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text
\begin{myframedeq}
  \begin{align}
    a & = b + c \\
    d & =e + f
  \end{align}
\end{myframedeq}

\FrameRule=1pt
\begin{myframedeq}[0.6\linewidth]
  \begin{align}
    a & = b + c \\
    d & =e + f
  \end{align}
\end{myframedeq}

\end{document}

score 2 · Answer 4 · answered Sep 17 '15 at 13:53

TikZ can also make much fun:

\documentclass[11pt]{report}
\usepackage{amsmath,tikz}
\usetikzlibrary{tikzmark}
\begin{document}

\begin{tikzpicture}[remember picture,overlay]
\draw[fill=blue!10]([yshift=0pt]{pic cs:start}) rectangle ([yshift=.5em]{pic cs:end});
\end{tikzpicture}

\tikzmark{start}
\begin{align}
 a &= b+c \\
 d &= e+f
\end{align}\hfill\tikzmark{end}

\end{document}

You can leave or drop the [fill=blue!10] to get the following outputs:

Equations and Equation Numbers within a Box

4 Answers4

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