[pstricks] unwanted framing line in plotImp

[Zbigniew Nitecki]

The code below
> \title{Brief Article}
> \author{The Author}
> 
> \begin{document}
> \maketitle
> %
> 	\begin{figure}[htbp]
> 	\begin{center}
> 			\begin{pspicture}(-0.5,-4.0)(4,2.0)
> 				\psline{<->}(0,0)(3.5,0)
> 				\psline{<->}(0,-4.0)(0,2.0)
> 				
> 				\psplotImp[algebraic](0,-8)(4,2){x^3+y^3+x*y-13}
> 				
> 				\rput(3,-2){$\bullet$}
> 				\uput[dr](3,-2){$(3,-2)$}
> 				\psline(2,-0.3)(4,-3.66)
> 				
> 			\end{pspicture}
> 	\caption{The Curve $x^{3}+y^{3}+xy=13$}
> 	\label{fig:impnew}
> 	\end{center}
> 	\end{figure}
> 		
> \end{document}

produces a picture with a framing line way below the figure:

There was a previous posting concerning a similar problem, but both Herbert's admonition to read the documentation,
and his example in the email, still leave me puzzled as to how to eliminate this line.

Zbigniew Nitecki
Department of Mathematics
Tufts University
Medford, MA 02155

telephones:
Office    (617)627-3843
Dept.    (617)627-3234
Dept. fax    (617)627-3966
http://www.tufts.edu/~znitecki/

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