SUSTATIC - Elevation static corrections, apply corrections from	
	      headers or from a source and receiver statics file	

     sustatic <stdin >stdout  [optional parameters]	 		

 Required parameters:							
	none								
 Optional Parameters:							
	v0=v1 or user-defined	or from header, weathering velocity	
	v1=user-defined		or from header, subweathering velocity	
	hdrs=0			=1 to read statics from headers		
 				=2 to read statics from files		
				=3 to read from output files of suresstat
	sign=1			=-1 to subtract statics from traces(up shift)
 Options when hdrs=2 and hdrs=3:					
	sou_file=		input file for source statics (ms) 	
	rec_file=		input file for receiver statics (ms) 	
	ns=240 			number of souces 			
	nr=335 			number of receivers 			
	no=96 			number of offsets			

 Notes:								
 For hdrs=1, statics calculation is not performed, statics correction  
 is applied to the data by reading statics (in ms) from the header.	

 For hdrs=0, field statics are calculated, and				
 	input field sut is assumed measured in ms.			
 	output field sstat = 10^scalel*(sdel - selev + sdepth)/swevel	
 	output field gstat = sstat - sut/1000.				
 	output field tstat = sstat + gstat + 10^scalel*(selev - gelev)/wevel

 For hdrs=2, statics are surface consistently obtained from the 	
 statics files. The geometry should be regular.			
 The source- and receiver-statics files should be unformated C binary 	
 floats and contain the statics (in ms) as a function of surface location.

 For hdrs=3, statics are read from the output files of suresstat, with 
 the same options as hdrs=2 (but use no=max traces per shot and assume 
 that ns=max shot number and nr=max receiver number).			
 For each shot number (trace header fldr) and each receiver number     
 (trace header tracf) the program will look up the appropriate static  
 correction.  The geometry need not be regular as each trace is treated
 independently.							


 Credits:
	CWP: Jamie Burns

	CWP: Modified by Mohammed Alfaraj, 11/10/1992, for reading
	     statics from headers and including sign (+-) option

      CWP: Modified by Timo Tjan, 29 June 1995, to include input of
           source and receiver statics from files. 

	modified by Thomas Pratt, USGS, Feb, 2000 to read statics from
 	     the output files of suresstat

 Trace header fields accessed:  ns, dt, delrt, gelev, selev,
	sdepth, gdel, sdel, swevel, sut, scalel, fldr, tracf
 Trace header fields modified:  sstat, gstat, tstat