%% 
%%  Example 03-01-4 
%%  Copyright (C) 2016 Herbert Voss
%% 
%% ==== 
% Show page(s) 1
%% 
%% 
\documentclass[]{screxa}
\pagestyle{empty}
\setlength\textwidth{158.31393pt}
\setlength\parindent{0pt}
%StartShownPreambleCommands

%StopShownPreambleCommands
\begin{document}
\[
  f(x) = \int \frac{\sin x}{x}\,\mathrm{d}x
\]
\[
  \displaywidth=0.5\linewidth
  f(x) = \int \frac{\sin x}{x}\,\mathrm{d}x
\]
\end{document}
