%% 
%%  The LaTeX Graphics Companion, 2ed (first printing May 2007)
%% 
%%  Example 5-2-1 on page 218.
%% 
%%  Copyright (C) 2007 Michel Goossens, Frank Mittelbach, Denis Roegel, Sebastian Rahtz, Herbert Vo\ss 
%% 
%%  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.
%% 

\documentclass{ttctexa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{207.83385pt}
\setlength\parindent{0pt}
\StartShownPreambleCommands
\usepackage{pstricks}
\StopShownPreambleCommands
\begin{document}
\begin{pspicture}(2,1)
  \psset{xunit=0.5mm,yunit=1mm}
  \psline{->}(20,10)
\end{pspicture}\\[0.75cm]
\psset{xunit=0.5mm,yunit=1mm}
\begin{pspicture}(20,10)
  \psline{->}(20,10)
\end{pspicture}
\end{document}