Wave-vector diagram for a 2D photonic crystal

Calculates and plots the photonic bands at constant frequency for a 2D photonic crystal.

This prog calculates and plots the wave-vector diagram (i.e. photonic bands at constant frequency) for a 2D photonic crystal consisting of cylinders with circular cross-section and
infinite height, arranged in a triangular lattice; oblique propagation is implicit, so the polarization states cannot be separated in E-pol and H-pol; 'omega'is taken as input;
Fourier coefficients for the expansion of dielectric constant are calculated analytically;
the materials considered here are dielectric and dispersionless, but dispersion can be added as a function e(omega)

The package contains the following programs:
pwem2Db.m - main program
epsgg.m - routine for calculating the matrix of Fourier coefficients of dielectric function
bz_irr2.m - routine for 2D discretization of irreducible Brillouin zone polygon;
kvect2.m - routine for calculating diagonal matrices with elements (kx+Gx) and (ky+Gy), where G=(Gx,Gy) is a reciprocal lattice vector
oblic_eigs.m - routine for solving the eigenvalue problem for
H-field