A general-purpose Green's function-based interpolator

A useful approach to data interpolation is to determine the Green's function for the interpolation operator and construct the interpolation from the super-positioning of suitably scaled Green's functions located at the data constraints. Such Green's functions have been determined for Cartesian splines in 1-, 2-, and 3-D, including regularized splines and splines in tension. Furthermore, these techniques have also been extended to spherical surfaces. I present a new command-line tool, greenspline, which acts as a general-purpose interpolator for both Cartesian and spherical surface data. The program runs on all platforms and is compatible with the Generic Mapping Tools.