%% 
%%  Example 01-04-3 
%%  Copyright (C) 2017 Herbert Voss
%% 
%% ==== 
% Show page(s) 1
%% 
%% 
\documentclass[]{screxa}
\pagestyle{empty}
\setlength\textwidth{304.62788pt}
\setlength\parindent{0pt}
%StartShownPreambleCommands
\usepackage{array}
%StopShownPreambleCommands
\begin{document}
\begin{equation}
x = \left\{%
   \begin{array}{l>{\raggedright}p{.5\textwidth}}%
      0 & if $A=\ldots$\tabularnewline
      1 & if $B=\ldots$\tabularnewline
      x & \parbox{0.5\columnwidth}{this runs with as much text as you like,
          because an automatic linebreak is given with
          a ragged right text. Without this
          \raggedright command, you'll get a formatted
          text like the following one \ldots\ but with a parbox \ldots\ it works}
    \end{array}%
  \right. %
\end{equation}
\end{document}
