Directional Method to Compute Reduced Matrix System in MBF Solvers

Computation of reaction terms in macro basis function (MBF) solvers is computationally very expensive. A directional cross approximation technique is used in this paper to compute the reaction terms, which is a multilevel low-rank compression technique. The motivation to use a directional method is to keep the compression rank bounded irrespective of subdomain size, so as a fast algorithm can be ensured. Apart from the computational efficiency, a controlled and very good accuracy can be obtained with the directional method. The application focus of this work is large antenna arrays.