\documentclass[12pt]{article}% Herbert Voss 2004-06-23
\usepackage{pstricks}
\usepackage{pst-plot}
\usepackage{pstricks-add}% version >=1.50
\pagestyle{empty}

\begin{document}
% Examples from Ulrich Dirr
\psset{plotpoints=200}
\begin{pspicture}*(-5,-5)(3,3)
 \psaxes[labelsep=.75mm,xyLabel=\footnotesize,
	arrowlength=1.75,%
	ticksize=2pt,%
	linewidth=0.17mm]{->}(0,0)(-4.99,-4.99)(3,3)
  \rput[Br](3,-.35){$x$}
  \rput[tr](-.15,3){$y$}
  \rput[Br](-.15,-.35){$0$}
  %
  \psset{linewidth=.35mm,polarplot=true}
  \psplot[linecolor=red]{140}{310}{3 neg x sin mul x cos mul x sin 3 exp x cos 3 exp add div}
  \psplot[linecolor=cyan]{140}{310}{6 neg x sin mul x cos mul x sin 3 exp x cos 3 exp add div}
  \psplot[linecolor=blue]{140}{310}{9 neg x sin mul x cos mul x sin 3 exp x cos 3 exp add div}
\end{pspicture}
\hfill
%
\begin{pspicture}(-2.5,-2.5)(2.5,2.5)
 \psaxes[labelsep=.75mm,xyLabel=\footnotesize,%
	arrowlength=1.75,%
	ticksize=2pt,%
	linewidth=0.17mm]{->}(0,0)(-2.5,-2.5)(2.5,2.5)
  \rput[Br](2.5,-.35){$x$}
  \rput[tr](-.15,2.5){$y$}
  \rput[Br](-.15,-.35){$0$}
  %
  \psset{linewidth=.35mm,plotstyle=curve,polarplot=true}
  \psplot[linecolor=red]{0}{360}{x cos 2 mul x sin mul}
  \psplot[linecolor=green]{0}{360}{x cos 3 mul x sin mul}
  \psplot[linecolor=blue]{0}{360}{x cos 4 mul x sin mul}
\end{pspicture}
%
\vspace{1cm}
\psset{unit=0.5}
\begin{pspicture}(-8.5,-8.5)(9,9) 
\psaxes[Dx=2,dx=2,Dy=2,dy=2,%
	labelsep=.75mm,xyLabel=\footnotesize,%
	arrowlength=1.75,%
	ticksize=2pt,%
	linewidth=0.17mm]{->}(0,0)(-8.5,-8.5)(9,9)
\rput[Br](9,-.7){$x$}
\rput[tr](-.3,9){$y$}
\rput[Br](-.3,-.7){$0$}
%
\psset{linewidth=.35mm,plotstyle=curve,polarplot=true}
\psplot[linecolor=blue]{0}{720}{8 2.5 x mul sin mul}
\end{pspicture}

\end{document}

