Note that “-0” in the q is for the beginning of the rotation. This “0” can be replaced with any number. For example, for an X-prop waveguide, the beginning of rotation is Z-cut when “-0”, the beginning is Y-cut when “-90”.

Besides, if needed, the dimensions of devices are also defined here.

freq_t and omega_t are prepared for the Absorbing Boundary Conditions. freq_t is the estimated frequency and omega_t is used to change the frequency into angular velocity.