DZDV - determine depth derivative with respect to the velocity

parameter, dz/dv, by ratios of migrated data with the primary
amplitude and those with the extra amplitude

dzdv <infile afile=afile dfile=dfile>outfile [parameters]

Required Parameters:
infile= input of common image gathers with primary amplitude
afile= input of common image gathers with extra amplitude
dfile= output of imaged depths in common image gathers
outfile= output of dz/dv at the imaged points
nx= number of migrated traces
nz= number of points in migrated traces
dx= horizontal spacing of migrated trace
dz= vertical spacing of output trace
fx= x-coordinate of first migrated trace
fz= z-coordinate of first point in migrated trace
off0= first offset in common image gathers
noff= number of offsets in common image gathers
doff= offset increment in common image gathers
cip=x1,z1,r1,..., cip=xn,zn,rn description of input CIGS
x x-value of a common image point
z z-value of a common image point at zero offset
r r-parameter in a common image gather

Optional Parameters:
nxw, nzw=0 window widths along x- and z-directions in
which points are contributed in solving dz/dv.


Notes:
This program is used as part of the velocity analysis technique developed
by Zhenyue Liu, CWP:1995.

Author: CWP: Zhenyue Liu, 1995

Reference:
Liu, Z. 1995, "Migration Velocity Analysis", Ph.D. Thesis, Colorado
School of Mines, CWP report #168.