SMOOTH3D - 3D grid velocity SMOOTHing by the damped least squares smooth3d outfile [parameters] Required Parameters: n1= number of samples along 1st dimension n2= number of samples along 2nd dimension n3= number of samples along 3rd dimension Optional Parameters: Smoothing parameters (0 = no smoothing) r1=0.0 operator length in 1st dimension r2=0.0 operator length in 2nd dimension r3=0.0 operator length in 3rd dimension Sample intervals: d1=1.0 1st dimension d2=1.0 2nd dimension d3=1.0 3rd dimension iter=2 number of iteration used time=0 which dimension the time axis is (0 = no time axis) depth=1 which dimension the depth axis is (ignored when time>0) mu=1 the relative weight at maximum depth (or time) verbose=0 =1 for printing minimum wavelengths slowness=0 =1 smoothing on slowness; =0 smoothing on velocity vminc=0 velocity values below it are cliped before smoothing vmaxc=99999 velocity values above it are cliped before smoothing Notes: 1. The larger the smoothing parameters, the smoother the output velocity. These parameters are lengths of smoothing operators in each dimension. 2. iter controls the orders of derivatives to be smoothed in the output velocity. e.g., iter=2 means derivatives until 2nd order smoothed. 3. mu is the multipler of smoothing parameters at the bottom compared to those at the surface. 4. Minimum wavelengths of each dimension and the total may be printed for the resulting output velocity is. To compute these parameters for the input velocity, use r1=r2=r3=0. 5. Smoothing directly on slowness works better to preserve traveltime. So the program optionally converts the input velocity into slowness ", and smooths the slowness, then converts back into velocity. Author: CWP: Zhenyue Liu March 1995 Reference: Liu, Z., 1994,"A velocity smoothing technique based on damped least squares in Project Reveiew, May 10, 1994, Consortium Project on Seismic Inverse Methods for Complex Stuctures.