[pstricks] Arrows on a parabola segment

[Herbert Voss]

Poul Riis schrieb:
> How can I make arrows on a parabola segment (with \parabola), similar to
> \ psline [ ArrowInside=->,ArrowInsidePos=20](0 ,0) (3 ,0)

\documentclass[10pt]{article}
\usepackage{pstricks}
\SpecialCoor
\begin{document}

\begin{pspicture}[showgrid=true](5,5)
\parabola[linewidth=1.5pt,linecolor=blue](4,4)(2,0)
\psset{linestyle=none}
\parabola[arrowscale=2,arrows=<->](3,1)(2,0)
\parabola[arrowscale=2,arrows=<->](!3.5 dup 2 sub dup mul)(2,0)
\end{pspicture}

\end{document}

Herbert