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From: bernhold@qtp.ufl.edu (David E. Bernholdt)
Newsgroups: comp.lang.fortran
Subject: Re: Array Notation
Message-ID: <1224@orange19.qtp.ufl.edu>
Date: 3 Jan 91 18:31:27 GMT
References: <1991Jan03.163532.22692@convex.com>
Reply-To: bernhold@qtp.ufl.edu (David E. Bernholdt)
Distribution: comp.lang.fortran
Organization: University of Florida Quantum Theory Project
Lines: 23

In article <1991Jan03.163532.22692@convex.com> psmith@convex.com (Presley Smith) writes:
>Array notation provides a simplified way to specify array operations
>in many cases, but may, in fact, decrease the performance of the program.
>[and gives a concrete example]

I know this has been discussed on this list before, and the point, as
I recall it, was that the F90 array syntax can require extra temporary
arrays and consequently extra operations to conform to the behavior
required by the standard. (Please correct me if that's wrong.)

Does the standard somehow mandate _different_ behavior for the same
loop written in DO vs array syntax?  Or is there some reason why 
the array syntax loop can't be transformed into a more efficient DO
loop structure automatically?

The end results are the same using either DO or array syntax,
right?  So if the array syntax is slower, it sounds to me like the
compiler (optimizer?) writers have a problem, not the language.
-- 
David Bernholdt			bernhold@qtp.ufl.edu
Quantum Theory Project		bernhold@ufpine.bitnet
University of Florida
Gainesville, FL  32611		904/392 6365