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From: btb@ncoast.UUCP
Newsgroups: comp.lang.misc
Subject: better ratfor ?
Message-ID: <1707@ncoast.UUCP>
Date: Tue, 18-Nov-86 13:48:46 EST
Article-I.D.: ncoast.1707
Posted: Tue Nov 18 13:48:46 1986
Date-Received: Wed, 19-Nov-86 09:05:35 EST
Reply-To: btb@ncoast.UUCP (Brad Banko)
Distribution: comp.org.decus
Organization: North Coast Public Access UN*X, Cleveland, OH
Lines: 39
Keywords: ratfor, fortran, optimize
Summary: ratfor preprocessor produces bad fortran code?

Hello,
	Does anybody know of a good ratfor preprocessor... one that doesn't
have some of the problems that our 3 have.... one that knows about f77?
	As an example, the ratfor for loop:

		for (i=1; i<=n; i = i + 1)

translates into the horrible:

		i = 1
		if (.not. (i .le. n)) goto (end of loop)
		...
		i = i + 1 (goto if)

rather than into the much more efficient:

		i = 1
		if (i .gt. n) goto (end of loop)
		...
		i = i + 1 (etc.)

this may not seem like much, but I have benchmarked the above optimization
change against the original code from a ratfor version of sieve, and it 
makes a factor of 2 difference... who knows how much more could be improved?
(Incidentally, the ratfor fortran sieve ran 5 times slower than either the
f77, or C sieve)
	We have a huge programming system all written in rat4... (Gipsy
image processing software), running on a lil' 11/750... 

	If you know of a "modern" rat4 we could get our hands on, I would
appreciate it...  I would also appreciate it if someone could tell me if
the above code is necessary in some way that I am not thinking of?

	Thanks,

-- 
			Brad Banko
			...!decvax!cwruecmp!ncoast!btb
			Cleveland, Ohio