Application of Interpolative Decomposition to FE-BI-MLFMA for Fast Computation of Monostatic Scattering from 3-D Complex Composite Objects

Interpolative decomposition (ID) algorithm is applied to the hybrid finite element-boundary integral-multilevel fast multipole algorithm (FE-BI-MLFMA) for fast computation of monostatic scattering from 3-D complex composite objects in this letter. The sparse skeleton directions are first selected from dense incident directions by employing ID. Then, the scattering fields from these skeleton directions are computed by FE-BI-MLFMA. Finally, scattering fields from any other interested directions can be constructed by the scattering fields from the skeleton directions. The numerical performance of ID for FE-BI-MLFMA has been investigated in detail through computing monostatic scattering by typical complex composite objects. It is observed that the skeleton directions by using ID are nonuniform and far less than directions uniformly selected. Furthermore, the result of skeleton directions by using ID is very robust and almost independent of procedures of using ID. Based on it, a two-level approach of using ID is first presented to reduce memory requirement in using ID in this letter.