SMatrAn is a numerical simulator for scattering matrix (S-matrix, S-parameters) derived from wave equation. The S matrix contains all the amplitude and phase information of reflected and transmitted waves from complex scatterers for incident waves. See "Wave scattering in frequency domain" to understand formulation of SMatrAn.
SMatrAnEM is developed for optics or microwave engineering. The source files of SMatrAnEM have been released under AGPLv3. They may be also made available under other licenses.
Currently, SMatrAnEM is tested to be confirmed, and the results will be updated. Please let me know if you have any questions and comments.