> Thin plate splines are just a special case of Polyharmonic Splines. Would > there be interest of expanding this script into a package?
Yes please, that would be great to have! > > -Luke > > On Wednesday, May 13, 2015 at 12:26:12 AM UTC-7, Jan Kybic wrote: > I have a set of irregularly gridded data (x,y,z) and I am trying to create an > interpolating surface using Thin Plate Splines. I couldn't find any existing > Julia routines so I thought I'd just do it my self. Here is my > implementation. As you can see its wrong. I been staring at it for a while > now and I am beginning to think I must be hitting some sort of bug or quirk > of the language. It either that or I did something wrong. If I get this to > work I was thinking about incorporating it into one of the existing > interpolation packages. > > Can anyone figure out why this is not working? > > > Hello. I have never seen the formulas you are using to find 'a' and 'b' and > I do not have the time to check. Provided they are correct, I would suspect > numerical problems - it is often not a good idea to calculate a matrix > inverse explicitely and the TPS matrix is ill-conditioned for even a moderate > number of points. I am attaching my Matlab implementation - you see that I am > solving the linear system by SVD, which is more stable. It should be trivial > to translate to Julia. Hope this helps. > > Jan
