Program sfexpand | Expand 2D data  
[SYNOPSIS]
sfexpand > out.rsf < in.rsf left=0.5*nx right=0.5*nx top=0 bottom=0
[PARAMETERS]
int     | bottom | =0 |   | 	
int     | left | =0.5*nx |   | 	
int     | right | =0.5*nx |   | 	
int     | top | =0 |   | 	
[DIRECTORY]
user/fangg
