“…Some methods for implementing these simplifications and calculation of the tensors are presented in [48]. Although, to our best knowledge, there is no commercial electromagnetic software on the market using GSTCs [50], [51], different numerical methods have employed GSTCs for electromagnetic simulation of metasurfaces, e.g., the discontinuous Galerkin time-domain (DGTD) in [50], [51], the finite difference time-domain (FDTD) in [12], [52], the finite-element method (FEM) in [53], the finite difference frequency-domain (FDFD) in [54], the spectral-domain integral equations (SD-IEs) in [55], the multifilament current (MFC) in [56], the IE-based method of moments (IE-MoM) in [57]. In [50], for example, they introduced the "virtual edges" after and before the metasurface to incorporate the DGTD method on GSTCs (see Fig.…”