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Plot3D question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg70622] Plot3D question
  • From: "dimitris" <dimmechan at yahoo.com>
  • Date: Sat, 21 Oct 2006 05:14:18 -0400 (EDT)

Hello again.

I would like to know why the Plot3D function does not complain about
the following command
(note there is a singularity at y=0)

Plot3D[Sin[x]/y, {x, -10, 10}, {y, -10, 10}]

whereas it does complain (a lot!) about the following

Plot3D[Sin[x]/y, {x, -10, 10}, {y, -10, 10}]

I believe it has to do with the non-adaptive algorithm used by Plot3D,
but even the command

Plot3D[Sin[x]/y, {x, -10, 10}, {y, -10, 10},PlotPoints->100]

does not change the behavior.

Note that I don't have any problem why the Plot function does not
complain about the
following command

Plot[Sin[x]/x, {x, 0, 10}];

since I understand that the adaptive algorithm actually does not sample
points at x=0

Short[Cases[%, {x_?NumberQ, y_?NumberQ} /; x = 0 && y > 0.9, 8], 2]

I really appreciate any comments/guidance/insight.

Thanks
Dimitris


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