Date: Mar 9, 2013 5:26 AM
Author: David Park
Subject: Re: dark halo around gaussian peak in Plot3D?
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@comcast.net

http://home.comcast.net/~djmpark/index.html

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

> > www.linkedin.com/in/michaelbheaney

> > ----------------------------------------------------------

> >

> >

>

--

----------------------------------------------------------

Michael B. Heaney

3182 Stelling Drive

Palo Alto, CA 94303 USA

mheaney@alum.mit.edu

www.linkedin.com/in/michaelbheaney

----------------------------------------------------------