LU factorization and solve of low rank electrically large MOM problems for monostatic scattering using the adaptive cross approximation for problem sizes to 1,025,101 unknowns on a PC workstation

When unknowns are grouped in local spatial regions, the resulting blocks of the system impedance matrix Z are of low numerical rank, a fact that has been reported and utilized by a number of investigators developing various approaches for "fast" MOM solutions such as FMM, AIM, pFFT, MLFMM, IES3. To date, these methods use iterative solvers to obtain the solution.