help with piecewise plane fitting

Hi, I used the SurfaceIntersection function developed by Jarek Tuszynski to generate the intersection between a surface and a cylinder: [intersect13, Surf13] = SurfaceIntersection(Surface1, Surface3); How can I perform piecewise plane fitting through the resulting intersection in order to compute the local variations of inclination and azimuth of each of these best fitting planes? Thanks and regards Marie