%% 
%%  The LaTeX Graphics Companion, 2ed (first printing May 2007)
%% 
%%  Example 5-13-28 on page 292.
%% 
%%  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{183.83385pt}
\StartShownPreambleCommands
\usepackage{pstricks}
\StopShownPreambleCommands
\begin{document}
\begin{pspicture}[showgrid=true](3,3)
  \pscustom[linewidth=1cm]{%
     \code{
        newpath
        20 20 moveto   0 50 rlineto
        50 0 rlineto   0 -50 rlineto
        -50 0 rlineto
        closepath
        2 setlinejoin
        7.5 setlinewidth
        stroke}%
     }
\end{pspicture}
\end{document}