Synopsis
		sfacurv < in.rsf > out.rsf rect1=1 rect2=1 rect3=1 order=2 nazmuth=10 interp=

Parameters
		string interp= interpolation method: maxflat lagrange bspline   int nazmuth=10 azimuth number   int order=2 approximating order of finite difference   int rect1=1 smoothness on 1st axis   int rect2=1 smoothness on 2nd axis   int rect3=1 smoothness on 3rd axis