Re: Question about interpolation and ListPlot3D

*To*: mathgroup at christensen.cybernetics.net*Subject*: [mg1493] Re: [mg1460] Question about interpolation and ListPlot3D*From*: twj (Tom Wickham-Jones)*Date*: Mon, 19 Jun 1995 01:26:10 -0400

Zvi Wiener writes > I have an array representing 3 dimensional points >in a form of their Eucledean coordinates: >arr = {{x1,y1,z1}, ... ,{xN,yN,zN}}; >(they were generated from a very smooth function). > >1. I wish to generate a 3D plot of this surface (approximately), >but format of ListPlot3D does not permit it, since my points >{xi, yi} do not form a regular grid. >How I can draw the surface? I have written a package SurfaceGraphics3D.m that will take data in the form {{x1,y1,z1}, ... ,{xN,yN,zN}} and plot a surface over it. >2. I would like to find value of this function at another point >{x, y}, the answer obviously depend on the way the function was >interpolated (extrapolated), but I am interested in any way, as >simple as possible. >How to extract the Interpolating Function's value at {x, y} ? I have a related package TriangularInterpolate.m that will do this. Both of these packages are based on some MathLink delaunay triangulation code. All the code is available in a set of packages I wrote called ExtendGraphics which is available from MathSource item number 0207-324. Tom Wickham-Jones WRI