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

*To*: mathgroup at smc.vnet.net*Subject*: [mg65794] Re: Plot3D: plot does not display when PlotPoints different from 25. Mathematica 5.2*From*: Bill Rowe <readnewsciv at earthlink.net>*Date*: Mon, 17 Apr 2006 02:28:50 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

On 4/16/06 at 3:49 AM, nma at 12000.org wrote: >Remove["Global`*"] >u[x_, y_] := Module[{}, >If[x == 0, Return[1 + y]]; If[y == 0, Return[1]]; Return[0]; >] >Plot3D[u[x, y], {x, -1, 2}, {y, -1, 2}, >FaceGrids -> None, AxesLabel -> {"U(x,y)", "x", "y"}, PlotLabel -> >"Boundary conditions", PlotPoints -> 25] >works OK. But if you change 25 to say 26 in the last line above, the >plot does not show up any more ! >Can someone explain why this is? Your function is everywhere 0 except for points on either the x or y axis. So, unless Mathematica happens to sample at either the x or y axis, it sees the function as constant. Changing the plot points changes where Mathematica does an initial sample. And obviously when the setting PlotPoints->26, the initial sample doesn't include a point on either the x or y axis. -- To reply via email subtract one hundred and four