Program sffd2d | 2-D Fourth-order Finite-difference wave extrapolation with ABC 
[SYNOPSIS]
sffd2d < Fw.rsf vel=Fv.rsf ref=Fr.rsf > Fo.rsf verb=0 nb=30 c=0.01
[PARAMETERS]
float   | c | =0.01 |   | 	decaying parameter 
int     | nb | =30 |   | 	boundary length 
file    | ref | = |   | 	auxiliary input file name
file    | vel | = |   | 	auxiliary input file name
bool    | verb | =0 |  [y/n] | 	setup I/O files 
[DIRECTORY]
user/jsun
