Program sffftwave1 | 1-D FFT wave extrapolation 
[SYNOPSIS]
sffftwave1 < inp.rsf > out.rsf prop=prop.rsf right=right.rsf nt= dt= sub=y step=y nsps=n
[PARAMETERS]
float   | dt | = |   | 	
bool    | nsps | =n |  [y/n] | 	if using NSPS 
int     | nt | = |   | 	
file    | prop | = |   | 	auxiliary input file name
string  | right | = |   | 	auxiliary input file name
bool    | step | =y |  [y/n] | 	if two-step propagation 
bool    | sub | =y |  [y/n] | 	if -1 is included in the matrix 
[DIRECTORY]
user/fomels
