SUINVXZCO - Seismic INVersion of Common Offset data for a smooth velocity function V(X,Z) plus a slowness perturbation vp(x,z) suinvvxzco outfile [optional parameters] Required Parameters: vfile file containing velocity array v[nx][nz] nx= number of x samples (2nd dimension) in velocity nz= number of z samples (1st dimension) in velocity nxm= number of midpoints of input traces Optional Parameters: dt= or from header (dt) time sampling interval of input data offs= or from header (offset) source-receiver offset dxm= or from header (d2) sampling interval of midpoints fxm=0 first midpoint in input trace nxd=5 skipped number of midpoints (see note) dx=50.0 x sampling interval of velocity fx=0.0 first x sample of velocity dz=50.0 z sampling interval of velocity nxb=nx/2 band centered at midpoints (see note) nxc=0 hozizontal range in which velocity is changed nzc=0 vertical range in which velocity is changed fxo=0.0 x-coordinate of first output trace dxo=15.0 horizontal spacing of output trace nxo=101 number of output traces ", fzo=0.0 z-coordinate of first point in output trace dzo=15.0 vertical spacing of output trace nzo=101 number of points in output trace ", fmax=0.25/dt Maximum frequency set for operator antialiasing ang=180 Maximum dip angle allowed in the image ls=0 =1 for line source; =0 for point source pert=0 =1 calculate time correction from v_p[nx][nz] vpfile file containing slowness perturbation array v_p[nx][nz] verbose=1 =1 to print some useful information Notes: Traveltime and amplitude are calculated by finite difference which is done only in one of every NXD midpoints; in the skipped midpoint, interpolation is used to calculate traveltime and amplitude. ", For each midpoint, traveltime and amplitude are calculated in the horizontal range of (xm-nxb*dx, xm+nxb*dx). Velocity is changed by constant extropolation in two upper trianglar corners whose width is nxc*dx and height is nzc*dz. Eikonal equation will fail to solve if there is a polar turned ray. In this case, the program shows the related geometric information. There are three ways to remove the turned ray: smoothing velocity, reducing nxb, and increaing nxc and nzc (if the turned ray occurs in the shallow areas). To prevent traveltime distortion from a over smoothed velocity, traveltime is corrected based on the slowness perturbation. Offsets are signed - may be positive or negative. Author: Zhenyue Liu, 08/28/93, Colorado School of Mines Reference: Bleistein, N., Cohen, J. K., and Hagin, F., 1987, Two-and-one-half dimensional Born inversion with an arbitrary reference Geophysics Vol. 52, no.1, 26-36.