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Occasionally data does not fit a hyperbolic curve very well.
Two other simple fitting functions are

| |
(34) |

| (35) |

Equation (34) has an extra adjustable parameter
of no simple interpretation other than the beginning of a power series in *x*^{2}.
I prefer Equation (35) where the extra adjustable parameter
is a time shift *t*_{0} which has a simple interpretation,
namely, a time shift
such as would result from a near-surface low velocity layer.
In other words, a datum correction.
1

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Stanford Exploration Project

12/26/2000