ALPS: An adaptive Lanczos—Padé spectral solution of mixed-potential integral equation Original Research Article

This paper presents the ALPS algorithm, a fast frequency sweep for solving Mixed-Potential Integral Equation (MPIE). By assuming a constant frequency parameter for the Greenʹs functions. ALPS employs Lanczos—Padé approximation with selective orthogonalization (MPVL) to obtain an approximate spectra solution. Repeating MPVL at another frequency gives a second spectra solution. ALPS determines at what frequency the difference between two spectral solutions is greatest and iteratively improves the spectral solution.