FDTD in Gsvit tutorial

Here we give a brief introduction into main concepts of Finite Difference in Time Domain Method, serving as a reference for Gsvit documentation. For much more details we refere to specialised books on FDTD, namely Taflove and Hagness one, that was used, together with some other articles listed in this tutorial to code the Gsvit package.

Together with description of basic FDTD algorithms we briefly list here how these algorithms are implemented and called in Gsvit. However, for more details how to run particular problems in Gsvit see the documentation and examples.