%% 
%%  A DANTE-Edition example
%% 
%%  Example 30-04-14 on page 613.
%% 
%%  Copyright (C) 2011 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[]{article}
\pagestyle{empty}
\setlength\textwidth{201.70511pt}
\setlength\parindent{0pt}

\usepackage{pstricks-add}

\begin{document}
\psset{xunit=.5,yunit=0.7,plotpoints=500,method=rk4}
\begin{pspicture}(0,-4.25)(24,5.25)
  \psaxes[Dy=2,dx=2]{->}(0,0)(0,-4)(24,5)
  \psplotDiffEqn[linewidth=1.5pt,linecolor=black!40,plotpoints=50]{0}{24}{5 0}%
     {dup 3 1 roll -4 div exch 2 mul sub}
  \psplotDiffEqn[linewidth=1.5pt,linecolor=black,algebraic]{0}{24}{5 0}%
     {y[1]|-y[1]/4-2*y[0]}
  \psplot[linestyle=dashed,linecolor=red]{0}{24}{% theoretic result
     Euler x -8 div exp x 127 sqrt 8 div mul RadtoDeg dup cos
     5 mul exch sin 127 sqrt div 5 mul add mul}
\end{pspicture}
\end{document}
