Program sferf | Bandpass filtering using erf function. 
[SYNOPSIS]
sferf < in.rsf > out.rsf flo=-1. fhi=-1. rect=1 spline=n der=n
[PARAMETERS]
bool    | der | =n |  [y/n] | 	compute derivative 
float   | fhi | =-1. |   | 	high frequency in band 
float   | flo | =-1. |   | 	low frequency in band 
float   | rect | =1 |   | 	filter sharpness 
bool    | spline | =n |  [y/n] | 	if use B-spline erf 
[DIRECTORY]
user/fomels
