Convert locations on the surface of a sphere in cartesian (X, Y, Z) coordinates to spherical (phi, lambda) coordinates.
sphere.cart.to.sphere.spherical(P, R = 1)
locations of points on sphere as N-by-3 matrix with labelled columns "X", "Y" and "Z"
radius of sphere
N-by-2 Matrix with columns ("phi" and "lambda") of locations of points in spherical coordinates
It is assumed that all points are lying on the surface of a sphere of radius R.