       Re: Interpolation over an irregular surface

• To: mathgroup at smc.vnet.net
• Subject: [mg39247] Re: Interpolation over an irregular surface
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Thu, 6 Feb 2003 03:06:51 -0500 (EST)
• Organization: Universitaet Leipzig
• References: <b1q6o9\$347\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Hi,

the easy way would be to edit the delaunay.tm file
and return the adjacence information (as written

If you don't like this you can make a loop over all
triangles, and append the point list in the triangle
to the adjacence list of every vertex in the triangle,
finaly build the Union[] of the adjacence list for every
vertex and remove the index k of the adjacence list for
vertex k.

Regards
Jens

Jacob Rome wrote:
>
> I'm trying to map (interpolate) temperatures from one 2D set of points
> to another for a finite element application.  The initial set of
> points is {x1,y1,t1} and the second set is {X1,Y1,T1}, and I know all
> the values except for T1. I have connectivity data for the new mesh
> {X1,Y1}, but not for the original mesh (x1,y1).
>
> I have downloaded the ExtendGraphics package, and it has a functions
> (TriangularInterpolate) which should do exactly what I need. No error
> is given when I initially use it
> (interpFunc=TriangularInterpolate[nodeTemp], where nodeTemp is a
> 3-column matrix). However, when I invoke it again (interpFunc[x1,y1]),
> I get a series of errors, primarily about reaching the recursion or
> iteration limits. Could this have to do with the size of the initial
> matrix (~15,000 sets of data), or is there a different problem? It
> only seems to work correctly when the point is outside of the initial
> region, or if all the nearest nodes have the same temperature.
>
> After this setback, I planned to use the Delaunay function in the same
> package to help write my own interpolation routine. Using this
> function should return three sets of data: the Convex Hull, Adjacency
> Matrix and the Triangles. However, it appears that only the Convex
> Hull and the Triangles are returned; to effectively write an
> interpolation routine, the Adjacency Matrix is crucial. How can I get
> this data from the Delaunay function?
>
> Any advice on solving this problem is greatly appreciated, whether you
> can suggest an alternative approach or provide a means to use these
> functions more effectively. Thank you.

```

• Prev by Date: Re: Formatted output
• Next by Date: RE: Simple Problem ??
• Previous by thread: Interpolation over an irregular surface
• Next by thread: On-line linear programming application