Usually geophysicists wish that there were no boundaries on the sides,
or that they were infinitely far away.
There are two kinds of side conditions to think about,
those in *x*, and those in *k*.

Often the side conditions on *x* are best approximated by
zero-slope side conditions.
It is possible to use more general side conditions because we
have previously learned to solve any tridiagonal system of equations.

The side conditions in *k*-space relate to the steepest dips.
A way to handle these dips
is to use to represent *k ^{2}*.
This introduces another adjustable parameter , which
must be kept less than 1/4.

10/31/1997