How to shorten equation left bracket?

Question

I need to make a table with some equations and the codes as follow:

\documentclass[12pt,a4paper]{article}
\usepackage[latin1]{inputenc}
\usepackage{amsmath,amsfonts,amssymb}    
\def\arraystretch{3}
\setlength\tabcolsep{0.5cm}
\begin{document}
\begin{tabular}{|l|l|}
\hline 
$|A|>B \Leftrightarrow \left[ \begin{array}{l}A>B\\A<-B\end{array}    \right.$&$|A|\geq B \Leftrightarrow \left[ \begin{array}{l}A \geq B\\A\leq -B\end{array} \right.$\\ 
\hline 
$\sqrt{A}>B \Leftrightarrow \left[ \begin{array}{l}\begin{cases}B <  0\\A\geq 0\end{cases}
\\\begin{cases}B\geq 0\\A>B^2\end{cases}
\end{array} \right.$ & $\sqrt{A}\geq B \Leftrightarrow \left[ \begin{array} {l}\begin{cases}B < 0\\A\geq 0\end{cases}
\\\begin{cases}B\geq 0\\A\geq B^2\end{cases}
\end{array} \right.$ \\ 
\hline 
\end{tabular} 
\end{document}

I want to shorten the left brackets so that they use less spaces. Thanks for help.

Remove the setting to \arraystretch – egreg Jul 04 '16 at 14:56 — egreg, Jul 04 '16 at 14:56
You may want to consider cases with square brackets – Jul 04 '16 at 16:06 — , Jul 04 '16 at 16:06

egreg · Answer 1 · 2016-07-04T17:58:44.370

The error is in setting \arraystretch to 3, because the setting is inherited also by the nested array environments.

With some visual formatting it's easier.

\documentclass[12pt,a4paper]{article}
\usepackage[latin1]{inputenc}
\usepackage{amsmath,amsfonts,amssymb}    
\begin{document}

\begin{tabular}{|l|l|}
\hline
&\\[-.5\normalbaselineskip]
$|A|>B \Leftrightarrow
\left[
  \begin{array}{l}
  A > B
  \\
  A < -B
  \end{array}
\right.$ &
$|A|\geq B \Leftrightarrow
\left[
  \begin{array}{l}
  A \geq B\\A\leq -B
  \end{array}
\right.$
\\
&\\[-.5\normalbaselineskip]
\hline 
&\\[-.5\normalbaselineskip]
$\sqrt{A}>B \Leftrightarrow 
\left[ 
  \begin{array}{l}
    \begin{cases}B <  0\\A\geq 0\end{cases}
    \\[4ex]
    \begin{cases}B\geq 0\\A>B^2\end{cases}
  \end{array}
  \right.$ &
$\sqrt{A}\geq B \Leftrightarrow
\left[
  \begin{array}{l}
    \begin{cases}B < 0\\A\geq 0\end{cases}
    \\[4ex]
  \begin{cases}B\geq 0\\A\geq B^2\end{cases}
\end{array} \right.$ \\[2.75\normalbaselineskip]
\hline 
\end{tabular} 

\end{document}

A different implementation with booktabs:

\documentclass[12pt,a4paper]{article}

\usepackage{amsmath,booktabs,array}

\begin{document}

$\begin{array}{
  @{}
  l
  @{}
  >{{}}c<{{}}
  @{}
  l
  @{\qquad}
  l
  @{}
  >{{}}c<{{}}
  @{}
  l
  @{}
}
\toprule
\addlinespace
|A|>B & \Leftrightarrow &
\left[
  \begin{array}{l}
  A > B
  \\
  A < -B
  \end{array}
\right. &
|A|\geq B & \Leftrightarrow &
\left[
  \begin{array}{l}
  A \geq B\\A\leq -B
  \end{array}
\right.
\\
\addlinespace
\midrule
\addlinespace
\sqrt{A}>B & \Leftrightarrow &
\left[ 
  \begin{array}{l}
    \begin{cases}B <  0\\A\geq 0\end{cases}
    \\
    \addlinespace
    \begin{cases}B\geq 0\\A>B^2\end{cases}
  \end{array}
  \right. &
\sqrt{A}\geq B & \Leftrightarrow &
\left[
  \begin{array}{l}
    \begin{cases}B < 0\\A\geq 0\end{cases}
    \\
    \addlinespace
    \begin{cases}B\geq 0\\A\geq B^2\end{cases}
\end{array} \right.
\\
\addlinespace
\bottomrule
\end{array}$

\end{document}

score 0 · Answer 2 · answered Jul 04 '16 at 17:10

This allows you to manually adjust the size of the \lbrace. I wouldn't advise using it, however.

\documentclass[12pt,a4paper]{article}
\usepackage[latin1]{inputenc}
\usepackage{amsmath,amsfonts,amssymb}    

\begin{document}
$\left\lbrace\rule{0pt}{2.5ex}\right. \begin{array}{@{}l@{}}B\geq 0\\A\geq B^2\end{array}$
\end{document}

How to shorten equation left bracket?

2 Answers2