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Re: dark halo around gaussian peak in Plot3D?

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  • Subject: [mg130104] Re: dark halo around gaussian peak in Plot3D?
  • From: "djmpark" <djmpark at comcast.net>
  • Date: Sat, 9 Mar 2013 05:27:44 -0500 (EST)
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Michael,

It looks to me like a numeric problem with very small numbers.  You can work
around it by clipping the function. Here I also scaled up the function by
100 just to get a convenient range.

Plot3D[100 Clip[
   PDF[BinormalDistribution[0], {x, y}], {10^-150, 20}], {x, -40, 
  40}, {y, -40, 40},
 PlotRange -> All,
 PlotPoints -> 30,
 Mesh -> None] 

If you decrease the lower Clip value by much you will get the "dark halo"
back. It seems to be associated with the front FaceForm losing its color.

Plot3D[100 Clip[
   PDF[BinormalDistribution[0], {x, y}], {10^-200, 20}], {x, -40, 
  40}, {y, -40, 40},
 PlotStyle -> Directive[FaceForm[Gray, Red]],
 PlotRange -> All,
 PlotPoints -> 30,
 Lighting -> "Neutral",
 Mesh -> None]


David Park
djmpark at comcast.net 
http://home.comcast.net/~djmpark/index.html 



From: Michael B. Heaney [mailto:mheaney at alum.mit.edu] 


Here is simple example that demonstrates the problem:

Plot3D[PDF[BinormalDistribution[0], {x, y}], {x, -40, 40}, {y, -40, 40},

 PlotRange -> All, PlotPoints -> 200]

Thanks,

Michael

On Thu, Mar 7, 2013 at 8:49 PM, Bob Hanlon <hanlonr357 at gmail.com> wrote:

> I don't see a "dark halo" with the following
>
> Plot3D[
>  PDF[BinormalDistribution[0], {x, y}],  {x, -3, 3}, {y, -3, 3}]
>
> Can you send a simple example that demonstrates the problem?
>
>
> Bob Hanlon
>
>
> On Thu, Mar 7, 2013 at 10:51 PM, Michael B. Heaney 
> <mheaney at alum.mit.edu>
> wrote:
> >
> > Hi,
> >
> > When I plot a gaussian peak in Plot3D, there is a dark halo around 
> > the peak. Why is this? How can I get rid of it?
> >
> > Thanks,
> >
> > Michael
> >
> > --
> > ----------------------------------------------------------
> > Michael B. Heaney
> > 3182 Stelling Drive
> > Palo Alto, CA 94303 USA
> > mheaney at alum.mit.edu
> > www.linkedin.com/in/michaelbheaney
> > ----------------------------------------------------------
> >
> >
>



--
----------------------------------------------------------
Michael B. Heaney
3182 Stelling Drive
Palo Alto, CA 94303 USA
mheaney at alum.mit.edu
www.linkedin.com/in/michaelbheaney
----------------------------------------------------------




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