Fast generalized forward-backward method by using a spectral acceleration

The generalized forward backward (GFB) method is a generalisation of the previous forward-backward (FB) method to compute the electromagnetic scattering from targets on ocean-like rough surfaces. In this paper, the spectral acceleration algorithm introduced by Chou and Johnson for the FB method is adapted to the GFB. This reduces the computational cost of the GFB from O(N/sup 2/) to O(N) per iteration.