I wrote:
> If the medium is not linear in this respect, we get a phenomena known as
> "dispersion," which in most materials results in the group velocity
> being lower than the phase velocity by a few percent, and sometimes a
> phenomena known as "anomalous dispersion" in which the phase velocity
> exceeds the group velocity.
Of course this last phrase should have read - "...in which the group
velocity exceeds the phase velocity."
It's too early in the morning to do physics. :)
--
Eric Michael Cordian 0+
O:.T:.O:. Mathematical Munitions Division
"Do What Thou Wilt Shall Be The Whole Of The Law"