Nested BiCGStab to solve complex linear systems arising from discretization of EFIE

Although in the last years the BiCGStab has been employed with success to handle large linear systems arising from the RWG MoM discretization of electromagnetic scattering problems formulated by EFIE, its nested version, the N-BiCGstab, has received little attention. In this work, an analysis of its performances is presented. It demonstrates that N-BiCGStab is, at least in the examined cases, faster and more robust than the standard BiCGStab coupled with diagonal or ILU preconditioning.