Python implementation of IDL's polywarp
Given lists xi, yi, xo, yo, determine kx and ky such that
xi[k] = sum over i and j from 0 to degree of: kx[i,j] * xo[k]^i * yo[k]^j
yi[k] = sum over i and j from 0 to degree of: ky[i,j] * xo[k]^i * yo[k]^j
usage:
import Polywarp
kx,ky = Polywarp.polywarp(xi,yi,xo,yo,degree=1)