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From: ravi@earth.ce.nwu.edu (Ravi Sinha)
Newsgroups: comp.lang.fortran
Subject: Re: Fortran 90 status
Message-ID: <1991May16.195328.727@casbah.acns.nwu.edu>
Date: 16 May 91 19:53:28 GMT
References: <CDHWILLI.91May13233601@exua.exua.exeter.ac.uk> <13372@exodus.Eng.Sun.COM> <23881@lanl.gov>
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In article <23881@lanl.gov> jlg@cochiti.lanl.gov (Jim Giles) writes:
>2) Real and Double precision DO control variables.
>
>   Agreed.  There must have been a strong lobby from some vendor to get
>   these into the standard to begin with.

Since I don't know much about how do loops are optimized, maybe someone
can cast some light on this.

Real DO control variables allow you to have loops like:
	DO r = 1,100000,0.1
	...
	ENDDO

The replacement with integer DO control variable would be:
	rbegin = 1
	rint = 0.1
	DO i=1,1000000
	r = rbegin + (i-1)*rint
	...
	ENDDO

Maybe someone can tell me why the second form is better from an
optimization point of view, and why the first form should be disallowed.

Ravi Sinha			|  <standard disclaimers here>
Northwestern University		|  <cute quote here>
ravi@earth.ce.nwu.edu		|  <cute quote continued here>