GdfidL: a finite difference program with reduced memory and CPU usage

Two new field solvers based on the FDTD algorithm are described. One solver computes resonant fields in loss-free structures, the other computes time dependent fields, scattering parameters and wake potentials in lossy or loss-free structures. The program uses linked lists instead of three dimensional arrays to model the computational volume. The main advantage of this approach is: Grid cells are only needed in regions, which are not filed with electric or magnetic conducting materials. This may result in an appreciable reduction of memory and CPU usage. The modeling via the linked lists is described in detail and some examples of calculated realistic geometries are given.