Convergence investigations of branch cut integrals occuring in a modified TSMFM fast integral equation solver

This contribution deals with some investigations about the convergence behavior of the group interaction integrals within a so-called Thin stratified medium fast multipole approach. Although first formulations of this type of fast integral equation solver were presented more than 10 years ago [2], no detailed convergence considerations of the pertinent group interaction integrals on the vertical branch cut have been published so far. With the known convergence properties, subsequently a robust and optimized solution behavior of the overall solver framework can be achieved using e.g. special quadrature techniques.