For the constant-coefficient, lossless and source-free case (i.e.,
), the numerical dispersion relation, in terms of the frequency and wavenumber magnitude
** will be, from (3.10),
**

which has roots

Discounting the stationary mode with , the phase and group velocities are then, from (3.12),

and if and are functions of and , the maximal group velocity will be

where . This bound is the same as for the (1+1)D transmission line equations.