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From: loki@physics.mcgill.ca (Loki Jorgenson Rm421)
Newsgroups: comp.sys.sgi
Subject: IRIXv3.3.1 FORTRAN I/O BUG
Message-ID: <9012030315.AA02428@frodo.Physics.McGill.CA>
Date: 3 Dec 90 03:15:29 GMT
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	This is being submitted on behalf of another IRIS user in our local
group who does not monitor info-iris (at least not until recently).  Please
let me know if this bug has already mentioned.
                             __          __
Loki Jorgenson	            / /          \ \  node:  loki@physics.mcgill.ca
Grad, Systems Manager      / //////  \\\\\\ \ BITNET: PY29@MCGILLA
Physics, McGill University \ \\\\\\  ////// / fax:   (514) 398-3733
Montreal Quebec CANADA	    \_\          /_/  phone: (514) 398-6531

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I believe I've discovered an Iris Fortran i/o bug.  It only occurs when 
printing out numbers smaller than E-100, so it only happens with double 
precision (real*8).  If the number is smaller than 1.E-100 the I/O routine 
'forgets' to print the letter E.  Consider output from the following trivial 
program:
	program		writetest
	integer         i, j
	real*8		tmp, temp
	tmp =  100.d0
	temp = 1.e-86
	do 100 i=1, 140
	     temp = temp / tmp
	     write(6,*) temp
100	continue
	stop
	end

The output is:
   1.0000000000000004E-88
   1.0000000000000004E-90
   1.0000000000000006E-92
   1.0000000000000004E-94
   1.0000000000000008E-96
   1.0000000000000008E-98
   1.0000000000000008-100      <--- note the E is missing !!!!
   1.0000000000000008-102
   1.0000000000000008-104
            .
            .
	and so on.....    

Thus any program reading this output gets gibberish.  Output also fails 
if you use an exponential format (eg g14.7) for output.  

** HOWEVER. **  
     1)  You can succesfully do i/o from unformatted files.
     2)  This problem does NOT occur in C.

So, how about it?  Anyone else notice this little gem?  How about you people
at SGI?  We are running 3.3.1, by the way, so I don't know if this was a 
bug in 3.2.1.  

		Ian.

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Ian Graham                   ------------     node:  igraham@physics.mcgill.ca
Physics, McGill University | * * *  * * * |   fax:   (514) 398-3733
Montreal Quebec CANADA	     ------------     phone: (514) 398-6526