Some new strategies for RCM ordering in solving electromagnetic scattering problems

We describe some ordering strategies for improving the incomplete Cholesky factorization used in the preconditioned conjugate gradient method applied to electromagnetic scattering problems. Some matrix ordering strategies, derived from the greedy partitioning algorithm for multilevel methods, are combined with RCM ordering. These ordering techniques are tested and compared with normal RCM ordering. Some tuning in selecting special nodes as first and last nodes in reverse Cuthill-McKee ordering is shown to apparently improve the quality of incomplete Cholesky factorization preconditioners.