A modified spectral shift preconditiner for electromagnetic scattering of complex objects

In order to efficiently solve large dense complex linear systems arising from electric field integral equations (EFIE) formulation of electromagnetic scattering problems, the multilevel fast multipole algorithm (MLFMA) is used to accelerate the matrix-vector product operations. This paper presents a modified spectral shift preconditioner, which is combined with other preconditioner can greatly improve the convergence of restart GMRES iterative method for large dense complex linear systems. Numerical experiments demonstrate that the modified spectral shift preconditioner combined with other preconditioner is very effective and can reduce the iteration number and the computational time significantly.