Synopsis
		sfchain2dfft < src.rsf > wht.rsf target=tgt.rsf init_w=w0.rsf init_wf=wf0.rsf fweight=fwht.rsf match=mch.rsf niter=0 liter=50 rect1=1 rect2=1 frect1=1 frect2=1

Parameters
		int frect1=1 smoothing in frequency dim1   int frect2=1 smoothing in frequency dim2   file fweight= auxiliary output file name   file init_w= auxiliary input file name   file init_wf= auxiliary input file name   int liter=50 number of linear iterations   file match= auxiliary output file name   int niter=0 number of iterations   int rect1=1 smoothing in time dim1   int rect2=1 smoothing in time dim2   file target= auxiliary input file name