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Re: A bug in ListPlot3D ?

• To: mathgroup at smc.vnet.net
• Subject: [mg65920] Re: [mg65906] A bug in ListPlot3D ?
• From: "David Park" <djmp at earthlink.net>
• Date: Sun, 23 Apr 2006 06:17:34 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

The plot looks all right to me.

It is easy to misinterpret what ListPlot3D does. You have a 3 x 4 matrix of
numbers. EACH and EVERY element in the array represents a z value. So the z
range goes from -3 to 60. The x and y ranges go from 1 to the number of
elements in each level of the array. That is, x goes from 1 to 3 and y goes
from 1 to 4.

Note that the three numbers you have in each list DO NOT represent the
coordinates of a point.

The data sample as you presented it does not contain any information as to
what the x and y domains are. If you wanted to specify what they were you
could use the MeshRange option in the plot.

You may need to fit a surface to your data. We would have to know more about
the nature of your actual data. You may have to use DeLaunayTriangulation.

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/

From: Hui Fang [mailto:fangh73 at xmu.edu.cn]
To: mathgroup at smc.vnet.net


I'm trying to use ListPlot3D to show a interesting surface. However, the
result is very confusing. Since my data is rather long, I'll just use 4
points to explain what happened.



ListPlot3D[{{3,55,-3},{3,60,-3},{4,55,-2},{4,60,-2.5}}]



The range of x and y axes are between {1,3} and {1,4} respectively, but the
y axes is supposed to be about 60! The worse thing is the z axis has a range
from 1 to 60, not showing anything NEGATIVE!



Anybody has any idea what's going on? I am using Mathematica 4.1. Thanks a
lot!



Dr. H. Fang

Department of Physics

Xiamen Univeristy

Xiamen, Fujian 361005