  Here, we report a numerical implementation of the nonlocal homogenization
approach recently proposed in [M. Silveirinha, Phys. Rev. B 75, 115104 (2007)],
using the finite difference frequency-domain method to discretize the
Maxwell-Equations. We apply the developed formalism to characterize the
nonlocal dielectric function of several structured materials formed by
dielectric and metallic particles, and in particular, we extract the local
permittivity, permeability and magnetoelectric coupling parameters when these
are meaningful. It is shown that the finite differences frequency domain
implementation of the homogenization method is stable and robust, yielding very
accurate results.
