Program sfpwd | 3-D plane wave destruction. 
[SYNOPSIS]
sfpwd < in.rsf dip=dip.rsf > out.rsf both=n n4=2 order=1 nj1=1 nj2=1 drift=n
[COMMENTS]

February 2013 program of the month:
http://ahay.org/blog/2013/02/09/program-of-the-month-sfpwd/

[PARAMETERS]
bool    | both | =n |  [y/n] | 	if y, compute both left and right predictions 
file    | dip | = |   | 	auxiliary input file name
bool    | drift | =n |  [y/n] | 	if shift filter 
int     | n4 | =2 |   | 	what to compute in 3-D. 0: in-line, 1: cross-line, 2: both 
int     | nj1 | =1 |   | 	in-line aliasing 
int     | nj2 | =1 |   | 	cross-line aliasing 
int     | order | =1 |   | 	accuracy 
[DIRECTORY]
user/pwd
