Path: utzoo!dptcdc!jarvis.csri.toronto.edu!mailrus!purdue!haven!adm!cmcl2!lanl!jlg
From: jlg@lanl.gov (Jim Giles)
Newsgroups: comp.lang.fortran
Subject: Re: yes vs. no on f8x
Message-ID: <12170@lanl.gov>
Date: 17 Apr 89 17:49:13 GMT
References: <590@loligo.cc.fsu.edu>
Organization: Los Alamos National Laboratory
Lines: 21

From article <590@loligo.cc.fsu.edu>, by mccalpin@loligo.cc.fsu.edu (John McCalpin):
> This seems to me to be a substantive issue.  I happen to work in
> vector-supercomputer-land, where efficiency is not a problem.  My codes
> will simply change from several thousands of lines of sequential DO loops
> to a few thousand lines of array notation.

I happen to work in vector-supercomputer-land - and efficiency is _the_
major problem.  This seems to represent the difference between university
computer attitudes and those of the "real world".

> [...]
> heard it rumoured that DEC opposes the array notation because the need
> to pass an array descriptor (rather than just a pointer to the start of
> the array) forces one more level of indirection in array references,
> [...]

Pass the whole descriptor by value.  The level of indirection remains
the same.  This can be done because the rank (number of dimensions)
of the array is known at compile time.  Therefore the size of the
descriptor is also known at compile time, and the correct code can
be generated for the call.