Gravitational potential (color-filled contours) of a massive ball inside a spherical domain. The domain extends radially over r ∈ [1,32], the massive ball has a radius of 1 and is offset from the origin by a cartesian displacement . This slice intersects the origin and is normal to the vector (0,−1,1) so as to intersect the mass. The boundary values of the potential are evaluated using spherical harmonics of order up to L = 8. The white circles are centered on the mass and correspond to theoretical iso-potential contours. The white disk r < 1 at the center is excluded from the computational domain.