%% 
%%  Ein Beispiel der DANTE-Edition
%%  
%%  7. Auflage
%% 
%%  Beispiel 29-02-9 auf Seite 653.
%% 
%%  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
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\documentclass[]{exaarticle}
\pagestyle{empty}
\setlength\textwidth{169.16928pt}
\setlength\parindent{0pt}
%StartShownPreambleCommands
\usepackage{pstricks-add}
%StopShownPreambleCommands
\begin{document}
\begin{pspicture}[showgrid=true](1,1)(5,5)
  \psset{linecolor=red}
  \psline{o-o}(1,1)(5,5)
  \psLNode(1,1)(5,5){0.75}{P1}\qdisk(P1){4pt}
  \psset{linecolor=blue}
  \psline{o-o}(4,3)(2,5)
  \psLNode(4,3)(2,5){-0.5}{P2}\qdisk(P2){4pt}
\end{pspicture}
\end{document}