Synopsis
		sfpick < scn.rsf > pik.rsf vel0=o2 niter=100 an=1. gate=3 smooth=y norm=n back=n rect#=(1,1,...) rect1=1 rect2=1 ...

rectN defines the size of the smoothing stencil in N-th dimension.

Theory in Appendix B of:
S. Fomel, 2009,
Velocity analysis using AB semblance: Geophysical Prospecting, v. 57, 311-321.
Reproducible version in RSFSRC/book/tccs/avo
http://ahay.org/RSF/book/tccs/avo/paper_html/

August 2012 program of the month:
http://ahay.org/blog/2012/08/01/program-of-the-month-sfpick/

Parameters
		float an=1. axes anisotropy   bool back=n [y/n] if run backward   int gate=3 picking gate   int niter=100 number of iterations   bool norm=n [y/n] if apply normalization (0.~1.)   int rect#=(1,1,...) smoothing radius on #-th axis   bool smooth=y [y/n] if apply smoothing   float vel0=o2 surface velocity

Used In
		BEI          vela/vscan wvs/vscan   DATA          alaska/line31-81-m8r