SMOOTH2 --- SMOOTH a uniformly sampled 2d array of data, within a user-
		defined window, via a damped least squares technique	

 smooth2 < stdin n1= n2= [optional parameters ] > stdout		

 Required Parameters:							
 n1=			number of samples in the 1st (fast) dimension	
 n2=			number of samples in the 2nd (slow) dimension	

 Optional Parameters:							
 r1=0			smoothing parameter in the 1 direction		
 r2=0			smoothing parameter in the 2 direction		
 win=0,n1,0,n2		array for window range				
 rw=0			smoothing parameter for window function		
 efile=                 =efilename if set write relative error(x1) to	
				efilename				

 Notes:								
 Larger r1 and r2 result in a smoother data. Recommended ranges of r1 	", 
 and r2 are from 1 to 20.						

 The file verror gives the relative error between the original velocity 
 and the smoothed one, as a function of depth. If the error is		
 between 0.01 and 0.1, the smoothing parameters are suitable. Otherwise,
 consider increasing or decreasing the smoothing parameter values.	

 Smoothing can be implemented in a selected window. The range of 1st   
 dimension for window is from win[0] to win[1]; the range of 2nd   	
 dimension is from win[2] to win[3]. 					

 Smoothing the window function (i.e. blurring the edges of the window)	
 may be done by setting a nonzero value for rw, otherwise the edges	
 of the window will be sharp.						



	Credits: 
		CWP: Zhen-yue Liu,
			adapted for par/main by John Stockwell 1 Oct 92
		Windowing feature added by Zliu on 16 Nov 1992