# [pstricks] Slicing a surface plot

David Tarazona daleotar at gmail.com
Sat Jul 9 01:18:34 CEST 2011

Hi and thank you Herbert for your awesome and continuous support...

I want to graph the function f(x,y) = x^4 + y^4 - 4xy + 1

So, above you'll find the code I'm using to plot the surface:

\documentclass{article}
\begin{document}
\psset{unit=1}
\psset{viewpoint=150 500 375,Decran=600}
\psset{lightsrc=viewpoint}
\begin{pspicture}(-4,-2)(4,5)
\psSolid[object=grille,base=-3 3 0 3,linecolor=gray,ngrid=6
6,RotX=-90](0,-3,3)
\psSolid[object=grille,base=-3 3 -3 3,linecolor=gray,ngrid=6 6](0,0,0)
\psSolid[object=grille,base=0 3 -3 3,linecolor=gray,ngrid=6
6,RotY=90](-3,0,3)
\psSurface[tablez=0.8 0.01 4 {} for,  zcolor=.666 0,ngrid=72
72,linewidth=0.01pt,algebraic,hue=0.5
1,Zmin=0,Zmax=3](-3,-3)(3,3){(x^4)+(y^4)-(4*x*y)+1}
\psPoint(3.5,-3.5,3){a} \uput{2pt}[l](a){$\scriptstyle f\left(x,y\right)$}
\psPoint(0,3,0){a} \uput{15pt}[dr](a){$\scriptstyle x_1$}
\psPoint(3,0,0){a} \uput{15pt}[dl](a){$\scriptstyle x_2$}
\end{pspicture}
\end{document}

I'm doing it right, however if you check the function at x=3, y=3 (which is
in the limits) f(3,3) = 127...

I want to graph just z values just between 0 and 3 like I'm trying to do
with Zmin=0,Zmax=3... however I think those Zmin, Zmax are used along with
axesboxed... So, I want to "slice" the graph so the values are between the
planes z=0 and z=3... Then, my question is:

How can I slice a plot surface?... or
How can I define an interval for z axis of the plot surface as well as X and
Y intervals?

Also thanks Herbert. Bye!

--
Att,

David Tarazona
Desarrollos Inteligentes - Mechcorp Ltda.
Tel: (57)(1) 700-6364
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