Ray tracing in an anisotropic absorbing medium

With the generalized group velocity v_g = Re (∂ω/∂k) for media with moderate absorption, derived in a previous paper, the Hamilton equations for group propagation in non-absorbing media are generalized to include moderate absorption. They contain directional derivatives not only in the direction of v but also in the direction of Im (∂ω/∂k). Two iterative computational methods are presented for ray tracing with the generalized Hamilton equations.