[pstricks] another confusion about \parametricplotThreeD

[Nitecki, Zbigniew H.]

I have a confusing situation:  the code below leads to the attached figure, which is OK except that the green curves
are supposed to be in the xz-plane (they have y=0) but instead they are in the yz-plane.  What can cause this anomaly?

BTW, can one use an algebraic notation option (instead of reverse Polish=postscript) in \parametricplotThreeD?

\begin{pspicture}(-3,-3.5)(3,3.5)
\newcommand{\Xellipse}[1]{
\pstThreeDEllipse[linecolor=blue]%
(#1,0,0)%
(0,36 #1 dup mul add sqrt 2 div,0)%
(0,0,36 #1 dup mul add sqrt 3 div )
}
\psset{unit=0.5}
\psset{Alpha=30}
\pstThreeDCoor%
[linecolor=black, xMin=-6, xMax=9,yMin=-0.9, yMax=8,zMin=-2.5, zMax=6]

\multido{\rx=-3+0.5}{11}{%
\Xellipse{\rx}%
}
\parametricplotThreeD[linecolor=red](-3,3){%
t
t dup t mul 36 add sqrt 2 div
0
}

\parametricplotThreeD[linecolor=red](-3,3){%
t
t dup t mul 36 add sqrt 2 div neg
0
}
\parametricplotThreeD[linecolor=green](-3,3){%
t
0
t dup t mul 36 add sqrt 3 div
}

\parametricplotThreeD[linecolor=green](-3,3){%
t
0
t dup t mul 36 add sqrt 3 div neg
}

\end{pspicture}

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