Sparse approximate inverse preconditioner for multiscale dynamic electromagnetic problems

The inherent difficulties of traditional preconditioning techniques are revealed by numerically analyzing characteristics of method of moments systems with respect to multiscale dynamic electromagnetic applications. Techniques are developed to solve these difficulties for the traditional sparse approximate inverse preconditioner. The proposed techniques include a skeleton-based filtering strategy aiming to overcome the awkward filtering strategy extensively employed in traditional preconditioners and the strategy to recover the block structure of the inverse matrix. The proposed techniques are investigated by numerical experiments on complex targets.