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MathGroup Archive 2006

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Re: Plot3D question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg70645] Re: Plot3D question
  • From: "dimitris" <dimmechan at yahoo.com>
  • Date: Sun, 22 Oct 2006 01:19:17 -0400 (EDT)
  • References: <ehcq6t$e$1@smc.vnet.net>

I think this post is a little cursed!
It can't be appeared correctly!
I will try another attempt!
---------------------------------------------------

I would like to apologise for the mistakes which obviously contained my
previous post.
Here comes the correct one:
---------------------------------------------------------------

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, 0, 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

Cases[%, {(x_)?NumberQ, (y_)?NumberQ} /;
   x >= 0 && y > 0.9, Infinity]

I really appreciate any comments/guidance/insight.

Thanks
Dimitris


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