The number of filter coefficients also controls the computer time
required by these techniques. Since the applications being considered
here are post-stack and generally fast,
at least for two-dimensional cases,
the computer time required is generally insignificant.
It is interesting to note that while the effective
t-x prediction time-domain filter has more
coefficients than the individual filters used in f-x prediction,
because f-x prediction
produces a different filter for each frequency,
the total number of filter coefficients is much larger
than the number for t-x prediction.
Nevertheless, the computer time needed to apply these two processes
in the two-dimensional case
is comparable,
since each filter calculated by f-x prediction is smaller than the single
filter calculated by t-x prediction.
Since the time to calculate a filter is proportional to *n ^{3}*, where

11/16/1997