Program sfsglfd2_tfd | 2-D 4th-order Staggered Grid Finite-difference wave extrapolation 
[SYNOPSIS]
sfsglfd2_tfd < fsource.rsf vel=fvel.rsf den=fden.rsf > fwf.rsf verb=n oo=4 spx= spz=
[PARAMETERS]
file    | den | = |   | 	auxiliary input file name
int     | oo | =4 |   | 	
int     | spx | = |   | 	source point in x 
int     | spz | = |   | 	source point in z 
file    | vel | = |   | 	auxiliary input file name
bool    | verb | =n |  [y/n] | 	verbosity
[DIRECTORY]
user/fangg
