SUPEF - Wiener predictive error filtering				

 supef <stdin >stdout  [optional parameters]				

 Required parameters:							
 	dt is mandatory if not set in header		 		

 Optional parameters:							
	minlag=dt		first lag of prediction filter (sec)	
	maxlag=last		lag default is (tmax-tmin)/20		
	pnoise=0.001		relative additive noise level		
	mincorr=tmin		start of autocorrelation window (sec)	
	maxcorr=tmax		end of autocorrelation window (sec)	
	showwiener=0		=1 to show Wiener filter on each trace	
	mix=1,...	 	array of weights (floats) for moving	
				average of the autocorrelations		

 Trace header fields accessed: ns, dt					
 Trace header fields modified: none					

 	To get the Wiener filters into an ascii file:			
 	... | supef ... showwiener=1 2>file | ...   (sh or ksh)		
 	(... | supef ... showwiener=1 | ...) >&file  (csh)		


 Credits:
	CWP: Shuki Ronen, Jack K. Cohen, Ken Larner
      CWP: John Stockwell, added mixing feature (April 1998)

	A. Ziolkowski, "Deconvolution", for value of maxlag default:
		page 91: imaxlag < nt/10.  I took nt/20.

 Notes:
	The prediction error filter is 1,0,0...,0,-wiener[0], ...,
	so no point in explicitly forming it.

	If imaxlag < 2*iminlag - 1, then we don't need to compute the
	autocorrelation for lags:
		imaxlag-iminlag+1, ..., iminlag-1
	It doesn't seem worth the duplicated code to implement this.

 Trace header fields accessed: ns