Synopsis
		sfofpwd2 < in.rsf > of.rsf np=100 p0= dp=2*p0/(1.-np) nq=100 q0= dq=2*q0/(1.-nq) order=1 nj=1 drift=n

Parameters
		float dp=2*p0/(1.-np) first dip sampling   float dq=2*q0/(1.-nq) second dip sampling   bool drift=n [y/n] if shift filter   int nj=1 antialiasing   int np=100 number of dips   int nq=100 number of dips   int order=1 [1,2,3] accuracy order   float p0= first dip origin   float q0= second dip origin