\documentclass{ppex}
\nonstopmode
\usepackage {graphics,pspicture}
\pagestyle{empty}
\setlength\textwidth{207.0pt}
\begin{document}
\ResetPreambleCommands
\ReadyForTheFray
\usepackage {graphics,pspicture}
\setlength{\unitlength}{1mm}
\begin{picture}(50,40)
\put(15,20){\circle{20}}
\put(40,20){%
 \scalebox{1}[2]{\circle{20}}}
\put(40,20){%
 \scalebox{1}[.5]{\circle*{20}}}
\end{picture}\qquad
\end{document}