为多条数学线添加支撑

为多条数学线添加支撑

我必须在对齐环境中使用大括号。意思是

\begin{align*}
 A ={}& B + \underbracemultiline{C + D + E \\
      & + F + G \\
      & + H + I \\
      & + J + K}_{=:M} + L
\end{align*}

结果是(一个很好的版本)
http://www.phoenixes.de/Bsp.png http://www.phoenixes.de/Bsp.png
另一种可能的语法是

\begin{align*}
 A ={}& B + \under{brace}{line}{dots}{C + D + E} \\
      & \under{dots}{brace}{dots}{+ F + G}_{=:M} \\
      & \under{dots}{line}{dots}{+ H + I} \\
      & \under{dots}{line}{brace}{+ J + K} + L
\end{align*}

\under{begin}{middle}{end}{What to under"line"}

符合示例的需要。我该怎么做?

谢谢

答案1

\underbrace由位构成,因此您只需每次使用不同的位复制其定义:

在此处输入图片描述

\documentclass{article}
\usepackage{amsmath}
\makeatletter
\def\underbracex#1#2{\mathop{\vtop{\m@th\ialign{##\crcr
   $\hfil\displaystyle{#2}\hfil$\crcr
   \noalign{\kern3\p@\nointerlineskip}%
   #1\crcr\noalign{\kern3\p@}}}}\limits}

\def\underbracea{\underbracex\upbracefilla}

\def\upbracefilla{$\m@th \setbox\z@\hbox{$\braceld$}%
  \bracelu\leaders\vrule \@height\ht\z@ \@depth\z@\hfill 
\kern\p@\vrule \@width\p@\kern\p@\vrule \@width\p@\kern\p@\vrule \@width\p@
$}

\def\underbraceb{\underbracex\upbracefillb}

\def\upbracefillb{$\m@th \setbox\z@\hbox{$\braceld$}%
\vrule \@width\p@\kern\p@\vrule \@width\p@\kern\p@\vrule \@width\p@\kern\p@
 \leaders\vrule \@height\ht\z@ \@depth\z@\hfill\bracerd
  \braceld\leaders\vrule \@height\ht\z@ \@depth\z@\hfill
\kern\p@\vrule \@width\p@\kern\p@\vrule \@width\p@\kern\p@\vrule \@width\p@
$}


\def\underbracec{\underbracex\upbracefillc}

\def\upbracefillc{$\m@th \setbox\z@\hbox{$\braceld$}%
\vrule \@width\p@\kern\p@\vrule \@width\p@\kern\p@\vrule \@width\p@\kern\p@
\leaders\vrule \@height\ht\z@ \@depth\z@\hfill
\kern\p@\vrule \@width\p@\kern\p@\vrule \@width\p@\kern\p@\vrule \@width\p@
$}

\def\underbraced{\underbracex\upbracefilld}
\def\upbracefilld{$\m@th \setbox\z@\hbox{$\braceld$}%
\vrule \@width\p@\kern\p@\vrule \@width\p@\kern\p@\vrule \@width\p@\kern\p@
 \leaders\vrule \@height\ht\z@ \@depth\z@\hfill\braceru$}


\makeatother
\begin{document}

\begin{align*}
 A ={}& B + \underbracea{C + D + E} \\
      &\underbraceb{{} + F + G}_{=:M} \\
      &\underbracec{{}+ H + I} \\
      &\underbraced{{} + J + K} + L
\end{align*}

\end{document}

相关内容