C                  INTERNATIONAL AVS CENTER
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C directory located at the International AVS Center ftp site and to include
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C that site.
C
C The International AVS Center, MCNC, the AVS Consortium and the individual
C submitting the module and files associated with said module provide absolutely
C NO WARRANTY OF ANY KIND with respect to this software.  The entire risk as to
C the quality and performance of this software is with the user.  IN NO EVENT
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C submitting the module and files associated with said module BE LIABLE TO
C ANYONE FOR ANY DAMAGES ARISING FROM THE USE OF THIS SOFTWARE, INCLUDING,
C WITHOUT LIMITATION, DAMAGES RESULTING FROM LOST DATA OR LOST PROFITS, OR ANY
C SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
C
C This AVS module and associated files are public domain software unless
C otherwise noted.  Permission is hereby granted to do whatever you like with
C it, subject to the conditions that may exist in copyrighted materials. Should
C you wish to make a contribution toward the improvement, modification, or
C general performance of this module, please send us your comments:  why you
C liked or disliked it, how you use it, and most important, how it helps your
C work. We will receive your comments at avs@ncsc.org.
C
C Please send AVS module bug reports to avs@ncsc.org.
C
C  NOTE:  THIS MODULE AND SOURCE CODE IS FOR USE 
C  WITH THE AVS SOFTWARE ENVIRONMENT ONLY 
	PROGRAM write_don4
C  Program to create the lat/long/time file required by read_segy
C  The lat/long/time file is used to bypass the trace header
C  information in the SEG "Y" file, which ought to contain this
C  data, and presumably do not.
C  Specification based simply on the use of the file within read_segy
C  as returned from AVS users.
C
C  author: john tee		date 11 October 1993

	integer time, ntraces
	real lat, long, latmin, latmax, longmin, longmax
	real latstep, longstep, timestep

C This ought to be the actual number of traces in the particular SEG "Y" file
	data ntraces / 4000 /
C Time appears not to be used in read_segy now - just set it as a counter
	data time / 1 /
C Lat/Long values are multiplied by 1.E06 and divided by .36E06 in read_segy (!)
	data latmin, longmin /0.0, 0.0 /
	data latmax, longmax /1.0, 1.0 /

	timestep = 1./float(ntraces)
	latstep = (latmax-latmin)/float(ntraces)
	longstep = (longmax-longmin)/float(ntraces)

	open(unit=10, file='./don4.flt', status='new', form = 'formatted')

	lat = latmin
	long = longmin
	do n=1, ntraces
	   write(10,1000) time, lat, long
	   time = n
	   lat  = lat+latstep
	   long = long+longstep
	enddo
1000	format(I8,2F12.8)

	close(10)

	stop
	end