Re: Plot3D: plot does not display when PlotPoints different from 25. Mathematica 5.2

*To*: mathgroup at smc.vnet.net*Subject*: [mg65772] Re: Plot3D: plot does not display when PlotPoints different from 25. Mathematica 5.2*From*: "Chris Chiasson" <chris.chiasson at gmail.com>*Date*: Mon, 17 Apr 2006 02:28:10 -0400 (EDT)*References*: <e1stnb$bk7$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Nasser Abbasi, I think it happens because the values of 1 will only be returned for independant variable values of y=0 or x=0. Plot3D does not take infinitecimal (sp?) steps, so it misses your lines. You are really trying to plot something that is almost infinitely small (look up the definition of Equal in mathematica - there is a bit of tolerance in there) and trying to see it in a plot of a surface that is very flat. Maybe you should just draw polygons for the boundary conditions? Your axes labels are probably in the wrong order. Show[Graphics3D/@{Block[{$DisplayFunction=Identity}, Plot3D[0,{x,-1,2},{y,-1,2},FaceGrids\[Rule]None, AxesLabel\[Rule]{"x","y","U(x,y)"}, PlotLabel\[Rule] "Boundary Conditions"]],{Polygon[{{0,-1,0},{0,2,3},{0,2,0}}], Polygon[{{-1,0,0},{-1,0,1},{2,0,1},{2,0,0}}]}}] Cheers,