我想将方程式和方程式数组整齐地放在一个框或框架内。我还喜欢在align环境中对齐对象，例如在eqnarray环境 [r|c|l] 中，请参见下面的示例。
工作示例：
\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?
结果：
编辑：那么多线方程呢？
Multiline:
\begin{align}
\Aboxed{ 1 + 2 = \pi - 0.14 \implies & \pi \in \mathbb{Q} \\
3 \ne \pi \implies & \pi \in \mathbb{R} }
\end{align}
也可以看看： 使用框架框在 eqnarray 之外创建环境