1

I want to nicely put equations and equations arrays inside a box or a frame. I also like to align objects in align environment like in the eqnarray environment [r|c|l], see example below.

Working example:

\documentclass{article}[A4]
\usepackage{amsmath,amssymb}

\newenvironment{bbox} {\par\smallskip\centering\begin{lrbox}{0}% \begin{minipage}[c]{0.99\textwidth}} {\end{minipage}\end{lrbox}% \framebox[0.99\textwidth]{\usebox{0}}% \par\medskip \ignorespacesafterend}

\begin{document}

\title{Box test}

I want to box equations. For a simple equation: \begin{equation} \label{1} \boxed{ 1 + 2 = \pi - 0.14 \quad \implies \quad \pi \in \mathbb{Q} } \end{equation} Eqnarray: \begin{eqnarray} 1 + 2 = \pi - 0.14 & \implies & \pi \in \mathbb{Q} \end{eqnarray} Align: \begin{align} 1 + 2 = \pi - 0.14 & \implies & \pi \in \mathbb{Q} \end{align} I want the \texttt{align} to be aligned like \texttt{eqnarray}, how to do that?

For align and eqnarray the \texttt{boxed} won't work, \begin{verbatim} \begin{align} \boxed{ 1 + 2 = \pi - 0.14 & \implies & \pi \in \mathbb{Q} } \end{align} \end{verbatim} Using the environment ``bbox'' it seems to work but has some space in the top so it looks a little bit ugly: \begin{bbox} \begin{align} 1 + 2 = \pi - 0.14 & \implies & \pi \in \mathbb{Q} \end{align} \end{bbox} I want it to look like equation \eqref{1}

How to do that?

The result: The result of this LaTeX code

Edit: What about multiline equations?

Multiline:
\begin{align}
\Aboxed{ 1 + 2 = \pi - 0.14   \implies & \pi \in \mathbb{Q}  \\
3 \ne \pi \implies & \pi \in \mathbb{R} } 
\end{align}

See also: Create environment out of eqnarray with frame box

Triceratops
  • 261
  • 1
  • 12
  • 1
    Unrelated: \documentclass{article}[A4] where do you have this syntax from? Because it is incorrect and where ever you have it from ought to be updated. – daleif Apr 04 '21 at 12:21
  • 1
    Do not use eqnarray , the spacing at the alignment point is not correct. To have a box around an equation in an align environment, you have the \Aboxed command defined by mathtools. – Bernard Apr 04 '21 at 12:44
  • Off-topic: You've transferred the alignment syntax from eqnarray to align. That's a mistake. Don't write 1 + 2 = \pi - 0.14 & \implies & \pi \in \mathbb{Q}. Instead, write 1 + 2 = \pi - 0.14 & \implies \pi \in \mathbb{Q}. Can you spot the difference? – Mico Apr 04 '21 at 13:16
  • Yes, the extra & which aligns [rcl]. – Triceratops Apr 05 '21 at 06:43

0 Answers0