Multilevel adaptive cross approximation (MLACA)

In recent years, several methods have been developed for accelerating the iterative solution of the electromagnetic integral equations discretized by Method of Moments (MoM). Most of them are based on the compressibility of parts of the MoM matrix when they correspond to the interaction between two distant boxes. Among them, a promising one is the Adaptive Cross Approximation (ACA) [1] which combined with a SVD recompression achieves very good results, especially for moderately large number of unknowns N. In this paper we propose a multilevel implementation of the ACA leading to a highly enhanced compression rate