Threshold-based Incomplete LU Factorization Preconditioner for Adaptive Integral Method

In this paper, the threshold-based incomplete LU (ILUT) factorization preconditioner is implemented to improve the convergence of the restarted generalized minimum residual [GMRES(m)] solver based on the adaptive integral method (AIM). The ILUT factorization implemented herein uses a dual dropping strategy to construct a preconditioner from the near-field matrix in the AIM. Numerical results show that the application of ILUT preconditioner leads to significant decrease in the number of iterations for both electric filed integral equation (EFIE) and combined field integral equation (CFIE).