Program sfzero | Zero crossings with sub-pixel resolution. 
[SYNOPSIS]
sfzero < inp.rsf > out.rsf nzero=nzero.rsf nw=4 down=n
[PARAMETERS]
bool    | down | =n |  [y/n] | 	only zeros on the way down 
int     | nw | =4 |   | 	Interpolation accuracy 
file    | nzero | = |   | 	auxiliary output file name
[DIRECTORY]
user/fomels
