A fast multipole accelerated block quasi minimum residual method for solving scattering from perfectly conducting bodies

A perfect electric conducting body illuminated by a time-harmonic incident field reacts according to the electric field integral equation (EFIE). In this paper, it has been shown that a block solver performs much better than a single right hand side solver, when one wants to solve for several different illuminating fields. This is independent of whether it is a direct or an iterative solver. A good preconditioner is necessary when solving iteratively. The block quasi minimum residual method (BQMR) and the modified sparse approximate inverse (SPAI) preconditioner together with the fast multipole method (FMM) are a good combination when solving this type of integral equation.