Fast algorithm for matrix-vector multiply of asymmetric multilevel block-Toeplitz matrices in 3-D scattering

A new O(N log N) FFT-based method to expedite matrix-Vector multiplies invo lving multilevel block-Toeplitz (MBT) matrices is presented. The method is also a minimal memory method with O(N) memory requirements because only non redundant entries of the MBT matrix are stored. The accuracy and convergenc e of the method are illustrated in the calculation of the scattered field a nd the effective permittivity of a sphere with size parameter ka up to 5 us ing a volume integral formulation akin to the discrete dipole approximation . (C) 2001 John Wiley & Sons, Inc.