%%
%%  Ein Beispiel der DANTE-Edition
%%
%%
%%  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
%%
\documentclass[]{exaarticle}
\pagestyle{empty}
\setlength\textwidth{190.324pt}
\setlength\parindent{0pt}
\StartShownPreambleCommands
\usepackage{pstricks-add}
\StopShownPreambleCommands
\begin{document}
\psset{unit=1.8cm}
\begin{pspicture}(-2.5,-1.5)(2.5,2.5)
 \psaxes{->}(0,0)(-2.5,-1.5)(2.5,2.5)
 \psplot[linewidth=1.5pt,algebraic]{-2.5}{+2.5}{(2*x+4)/(2+x^2)}
 \psline[linestyle=dashed](-1.5,-1.5)(2.5,2.5)
 \def\function{ xVal dup add 4 add xVal dup mul 2 add div }%
 \pstVerb{ /xVal -1 def }% start value
 \multido{\nA=0+1}{10}{%
   \psline[linestyle=dotted](! xVal 0 )(! xVal xVal)
   \psline[linecolor=red](! xVal xVal )(! xVal \function )
   \psline[linecolor=red](! xVal \function )(! \function\space dup)
   \pstVerb{ /xVal \function\space def}%
 }
\end{pspicture}
\end{document}