SMOOTHINT2 --- SMOOTH non-uniformly sampled INTerfaces, via the damped
  		least-squares technique					

  smoothint2 <input ninf= >output [optional parameters]		

 Required Parameters:							
 <input                 file containing original interfaces		
 >output                file containing smoothed interfaces	 	

 Optional Parameters:							
 ninf=5                number of interfaces  				
 r=100			smoothing parameter 				
 npmax=101		maximum number of points in interfaces		

 Notes:								
 The input file is an ASCII file. Each interface is represented by pairs
 (non-uniform sampling) of x and z values, with one pair of values on	
 each line, separated by spaces or tabs. Each interface is separated with
 an entry with a large negative z value for example: 1.0     -9999.	
 There is no entry for the surface. The surface is assumed to be flat  
 with z=0.								
 This is similar to a CSHOT model file without a surface entry and	
 without comments.							

 The smoothing method is analogous to a moving window averaging process
 (but not the same) with the parameter "r" being analogous to the "width
 of the window. Thus, the size of "r" must be chosen to by compatible
 with the scale (wavelengths) of the variations of the interfaces in the
 model being smoothed.							

 Example using the test data set generated by unif2: 			
 unif2 tfile=tfilename							
 Compare the unsmoothed interface model:				
 unif2 < tfilename method=interpolation_method |			
	 			psimage n1=100 n2=100 d1=10 d2=10 | ...	
 To the smoothed interface model:					
 smoothint2 r=100 < tfilename | unif2 method=interpolation_method |	", 
	psimage n1=100 n2=100 d1=10 d2=10 | ...				



 Credits:
  CWP: Zhenyue Liu, Jan 1994
 Reference:
    Liu, Zhenyue, 1994, Velocity smoothing: theory and implementation, 
    Project Review, 1994, Consortium Project on Seismic Inverse Methods
    for Complex Stuctures (in review)