“…In more recent years, McWhirter and Pike 23 introduced a new approach, known as the analytic eigenfunction theory, which is based on the Mellin transform of the kernel function. This technique, which is particularly suited to problems in which the kernel is a relatively simple analytical function, was applied by Viera and Box 24 and by Bertero and co-workers 25,26 to the inversion of spectral extinction data in the anomalous diffraction approximation. Recently Box et al 27 applied the eigenfunction theory, using the exact Mie extinction kernel, and obtained satisfactory computer simulations, although with a tendency to overestimate the content in small particles.…”