“…Specially, a 2D FMM implemented via pulse expansion functions and point matching that can handle arbitrary polarization of electric and magnetic fields/currents is proposed here, that can solve large scale GSTC/metasurface problems. While an accelerated IE solver has also been applied to large scale environments before in the literature using a volume integral equation method [36]- [38], the use of volume integral makes this method unable to incorporate GSTCs. Although, the FMM is commonly applied to two dimensional scattering problems [33], [35], much of what is reported in the literature is developed for either TM z or TE z polarization (in terms of EFIE, MFIE or CFIE integrals), which are not easily extendable to general metasurface boundaries where both the electric and magnetic fields are tightly coupled through the surface susceptibilities in the GSTCs.…”