%% 
%%  An UIT Edition example
%% 
%%  Example 04-05-1 on page 38.
%% 
%%  Copyright (C) 2010 Herbert Voss
%% 
%%  It may be distributed and/or modified under the conditions
%%  of the LaTeX Project Public License, either version 1.3
%%  of this license or (at your option) any later version.
%% 
%%  See http://www.latex-project.org/lppl.txt for details.
%% 
%% 
%% ==== 
% Show page(s) 1
%% 
\documentclass[]{exaarticle}
\pagestyle{empty}
\setlength\textwidth{201.70511pt}
\usepackage[utf8]{inputenc}
\AtBeginDocument{\setlength\parindent{0pt}}
\StartShownPreambleCommands

\StopShownPreambleCommands
\begin{document}
\[ \mathrm{sgn}(x)=\left\{
  \begin{array}{rl}
    -1 & \textrm{for } x<1 \\
     0 & \textrm{for } x=0 \\
     1 & \textrm{for } x>1
  \end{array}  \right. \]
\end{document}
