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 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.