Ellipsoid fit

Fits an ellipsoid or other conic surface into a 3D set of points approximating such a surface, allows some constraints, like orientation constraint and equal radii constraint. E.g., you can use it to fit a rugby ball, or a sphere. 'help ellipsoid_fit' says it all. Returns both the algebraic description of the ellipsoid (the nine coefficients of the quadratic form) and the geometric description (center, radii, principal axes).