Scattering by two and three spheres computed by the generalized multipole technique

An analytic solution to the problem of scattering by multiple spheres was given by J.H. Bruning and Y.T. Lo (ibid., vol.AP-19, p.378-90 and 391-8, May 1971). Results from this analytic solution are compared to results obtained using the generalized multipole technique (GMT), a numerical method that uses vector spherical harmonics as basis functions. The boundary conditions are imposed at a discrete set of points and the solution is obtained by numerically inverting a system of linear equations. The problem is particularly well suited to the GMT because the surfaces are very smooth