Program sffwigrad | 2D Gradient Calculation in Full Waveform Inversion 
[SYNOPSIS]
sffwigrad < in.rsf > out.rsf misfit=misfit.rsf source=source.rsf receiver=receiver.rsf record=record.rsf npml=20 omega= order=
[PARAMETERS]
file    | misfit | = |   | 	auxiliary output file name
int     | npml | =20 |   | 	
float   | omega | = |   | 	
string  | order | = |   | 	discretization scheme (default optimal 9-point) 
file    | receiver | = |   | 	auxiliary input file name
file    | record | = |   | 	auxiliary input file name
file    | source | = |   | 	auxiliary input file name
[DIRECTORY]
user/zhiguang
