SEGYWRITE - write an SEG-Y tape					

 segywrite <stdin tape=						

 Required parameters:							
	tape=		tape device to use (see sudoc segyread)		

 Optional parameter:							
	verbose=0	silent operation				
			=1 ; echo every 'vblock' traces			
	vblock=50	echo every 'vblock' traces under verbose option 
	buff=1		for buffered device (9-track reel tape drive)	
			=0 possibly useful for 8mm EXABYTE drive	
	conv=1		=0 don't convert to IBM format			
	hfile=header	ebcdic card image header file			
	bfile=binary	binary header file				
	trmin=1 first trace to write					
	trmax=INT_MAX  last trace to write			       
	endian=1	=0 for little-endian machines (PC's, DEC,etc...)
	errmax=0	allowable number of consecutive tape IO errors	
	format=		override value of format in binary header file	

 Note: The header files may be created with  'segyhdrs'.		


 Note: For buff=1 (default) tape is accessed with 'write', for buff=0	
	tape is accessed with fwrite. Try the default setting of buff=1 
	for all tape types.						
 Caveat: may be slow on an 8mm streaming (EXABYTE) tapedrive		
 Warning: segyread or segywrite to 8mm tape is fragile. Allow time	
	   between successive reads and writes.				
 Precaution: make sure tapedrive is set to read/write variable blocksize
	   tapefiles.							

 For more information, type:	sudoc <segywrite>			



 Warning: may return the error message "efclose: fclose failed"
	 intermittently when segyreading/segywriting to 8mm EXABYTE tape,
	 even if actual segyread/segywrite is successful. However, this
	 may indicate that your tape drive has been set to a fixed block
	 size. Tape drives should be set to variable block size before reading
	 or writing tapes in the SEG-Y format.

 Credits:
	SEP: Einar Kjartansson
	CWP: Jack, Brian, Chris
	   : John Stockwell (added EXABYTE functionality)
 Notes:
	Brian's subroutine, float_to_ibm, for converting IEEE floating
	point to IBM floating point is NOT portable and must be
	altered for non-IEEE machines.	See the subroutine notes below.

	On machines where shorts are not 2 bytes and/or ints are not 
	4 bytes, routines to convert SEGY 16 bit and 32 bit integers 
	will be required.

	The program, segyhdrs, can be used to make the ascii and binary
	files required by this code.