\documentclass{article} \usepackage{pstricks} % To use the standard "color" package with PSTricks \usepackage{multido} \input{random.tex} % From Donald Arseneau (on macros/generic on CTAN) \newdimen\dX \newdimen\dY \newdimen\Coor % Random walk in the unit square (#1 = number of steps) \def\RandomWalk#1{% \setrandim\dX{0pt}{1pt} \setrandim\dY{0pt}{1pt} \psdot[dotstyle=*,dotsize=6pt](\pointless\dX,\pointless\dY) % Initial point \pscustom{% \moveto(\pointless\dX,\pointless\dY) % Move to initial point \multido{\i=1+1}{#1}{% \MoveCoordinate{\dX} \MoveCoordinate{\dY} \lineto(\pointless\dX,\pointless\dY)}}} % Line between old and new position % Computation of new horizontal or vertical position of point \def\MoveCoordinate#1{% \setrandim\Coor{-0.06pt}{0.06pt} % The move \advance #1 by \Coor % New position % To stay in the square... \ifdim#1>1pt #1=1pt\fi \ifdim#1<0pt #1=0pt\fi} \pagestyle{empty} \parindent=0pt \begin{document} \psset{unit=7,dimen=middle,linewidth=0.5pt} \begin{pspicture}(1,1.01) \psframe[linewidth=0.1pt](1,1) \RandomWalk{300} \psset{linecolor=red} \RandomWalk{300} \psset{linecolor=green} \RandomWalk{300} \end{pspicture} \end{document}