Synopsis
		sfTesteb < Fv.rsf > Fw1.rsf back=Fw2.rsf nb=20 nt= dt= fm=20.0 ft=0 jt=1 ns=1 ng=nx

The sponge absorbing boundary condition is applied for simplicity!
2N-order FD: effective boundary needs N points on each side!
Note: In this demo, 2N=4 (N=2).

Parameters
		file back= auxiliary output file name   float dt= time sampling interval   float fm=20.0 dominant freq of Ricker wavelet   int ft=0 first recorded time   int jt=1 time interval   int nb=20 thickness of sponge ABC   int ng=nx number of receivers   int ns=1 number of shots   int nt= number of time steps

Used In
		XJTU          primer/testeb