\documentclass{article}
\usepackage{pstricks}
\pagestyle{empty}
\parindent=0pt
\begin{document}

\begin{center}
\begin{pspicture}(8,4)  \psgrid[subgriddiv=0]
  \psset{linewidth=2pt,showpoints=true}
  \pscurve[arrows=->,arrowscale=3,linecolor=red](0,0)(1,3)(2,1)(6,3)(2,3.5)(1,1)
  \pscurve*[linecolor=blue](5,0)(5,1)(6,0)(8,4)
  \pscurve[linecolor=red](5,0)(5,1)(6,0)(8,4)
\end{pspicture}
\end{center}

\end{document}
