SUMIGSPLIT - Split-step depth migration for zero-offset data.

sumigsplit <infile >outfile vfile= [optional parameters]

Required Parameters:
nz= number of depth sapmles
dz= depth sampling interval
vfile= name of file containing velocities

Optional Parameters:
dt=from header(dt) or .004 time sampling interval
dx=from header(d2) or 1.0 midpoint sampling interval
ft=0.0 first time sample
fz= first depth sample

tmpdir= if non-empty, use the value as a directory path
prefix for storing temporary files; else if the
the CWP_TMPDIR environment variable is set use
its value for the path; else use tmpfile()



The vfile parameter must be specified, the velocity should be stored in
binary format in vfile, its structure should be vfile[iz][ix].



Credits: CWP Baoniu Han, July 21th, 1997

Reference:
Stoffa, P. L. and Fokkema, J. T. and Freire, R. M. and Kessinger, W. P.,
1990, Split-step Fourier migration, Geophysics, 55, 410-421.


Trace header fields accessed: ns, dt, delrt, d2
Trace header fields modified: ns, dt, delrt