ahmilb@houu64$sufrac

SUFRAC -- take general (fractional) time derivative or integral of

data, plus a phase shift. Input is TIME DOMAIN data.

sufrac power= [optional parameters] <indata >outdata

Optional parameters:

power=0 exponent of (-i*omega)

=0 ==> phase shift only

>0 ==> differentiation

<0 ==> integration

sign=-1 sign in front of i * omega

dt=(from header) time sample interval (in seconds)

phasefac=0 phase shift by phase=phasefac*PI

Examples:

preprocess to correct 3D data for 2.5D migration

sufrac < sudata power=.5 sign=1 | ...

preprocess to correct susynlv, susynvxz, etc. (2D data) for 2D migration

sufrac < sudata phasefac=.25 | ...

The filter is applied in frequency domain.

if dt is not set in header, then dt is mandatory

Algorithm:

g(t) = Re[INVFTT{ ( (sign) iw)^power FFT(f)}]

Caveat:

Large amplitude errors will result if the data set has too few points.