Non-sequential Field Tracing
As one of the fundamental strategies in field tracing, an optical system is divided into regions which can be modeled with a specialized regional solver, and then the interconnection of all regions delivers the solution to the complete system. Following Neumann's series, it can be shown that a non-sequential interconnection of all regions leads to a rigorous iterative solution of the system, given that numerical convergence is reached.
M. Kuhn, F. Wyrowski, C. Hellmann, Non-sequential optical field tracing, T. Apel and O. Steinbach, editors, Advanced Finite Element Methods and Applications, volume 66 of Lecture Notes in Applied and Computational Mechanics, pages 257-273. Springer Berlin Heidelberg (2013).