[pstricks] plotting in polar coordinates

[Herbert Voss]

juanleal at cantv.net wrote:

> Is it possible to plot in polar cooordinates the lemniscata 
> r^2=3cos(2\theta) with pstricks? How?

\documentclass{article}
\usepackage{pstricks-add}

\begin{document}
\newcommand{\rau}{2 x mul cos 3 mul sqrt}
\psset{unit=2cm}
\begin{pspicture}(-3,-3)(3,3)
   \psplot[polarplot,plotpoints=500]{-45}{45}{x dup add cos 3 mul sqrt}
   \psplot[polarplot,plotpoints=500]{135}{225}{x dup add cos 3 mul sqrt}
\end{pspicture}
\end{document}


Herbert