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From: woods@hao.UUCP (Greg Woods)
Newsgroups: net.lang.f77
Subject: Re: 4.2 f77 compiler comments
Message-ID: <990@hao.UUCP>
Date: Tue, 29-May-84 15:42:56 EDT
Article-I.D.: hao.990
Posted: Tue May 29 15:42:56 1984
Date-Received: Sat, 2-Jun-84 09:23:19 EDT
References: <4214@ukc.UUCP>
Organization: High Altitude Obs./NCAR, Boulder CO
Lines: 27


  I implemented the EISPACK eigenvalue package under 4.2 here, and there are
definitely bugs in the optimizer, and we too have installed all of Don
Seely's bug fixes. When the optimized code *does* run properly, we have 
observed some of our programs running twice as fast when using the optimized
EISPACK. If we could only find *all* the bugs in the optimizer, we would
have a *real* FORTRAN for UNIX! :-) BTW, as far as I can tell, without the
optimizer our compiler is almost fully reliable, now that we fixed a bug that 
kept integer exponentiation from working. One remaining problem is in
equivalences, which I have mentioned before. If you have a non-normalized 
floating point number on the right-hand side of an assignment, occasionally 
the result will be a zero word even though the RHS was non-zero. Example:

       equivalence(f,i),(g,j)
       i=100
       g=f
       write(6,*) j

will print 0. On the other hand, if you change "100" to "200", then it will
print "200" as you would expect. The cutoff point is 128.

	   Greg "FORTRAN hacker" Woods
-- 
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