[pstricks] Avoid lines in psplotImp

[Herbert Voss]

Martin Chicoine wrote:
> Is there a way to avoid the superfluous lines in this example?
>   
as shown in the docs ...

\documentclass[11pt]{article}

\usepackage{pst-func,pstricks-add}
\psset{algebraic}
\begin{document}

\begin{psgraph*}(0,0)(-6,-6)(8,6){8cm}{!}
  \psplotImp[linecolor=red](-7,-7)(0,0){x^3*y^2-3*x^2*y^3-(16)}
  \psplotImp[linecolor=violet](0,-7)(8,0){x^3*y^2-3*x^2*y^3-(16)}
\end{psgraph*}

\end{document}

Herbert