Synopsis
		sfspefcstep < inp.rsf > out.rsf infil=infil.rsf verb=n na= ngp=0 lambda1= lambda2=0.0f

Parameters
		string infil= initial filter (auxiliary input file name)   float lambda1= constant scale parameter in time axis   float lambda2=0.0f constant scale parameter in space axis   int na= filter size   int ngp=0 constant step   bool verb=n [y/n]