I'm trying to port `interpolation.affine_transform`  to
another langage and I have a question about your algorithm. I
successfully ported order 1 (linear) interpolation from another
lib, but I failed on order 3 (cubic).
I tried reading the interpolation code (zoom shift)  but it's
no simple task. So, I took vtk implementation  and ported it,
but I can't get your results. I was surprised because it's a
mathematical formula, it should give the same result wathever the
So, my question is: is there something special with SciPy's
cubic interpolation? I don't get the feeling that the code
fits the description in wikipedia . Also, I saw the
`spline_filter` function, I ported it and but I still can't get
the same results, disabled or not.