Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!nrl-cmf!cmcl2!beta!a!jlg
From: jlg@a.UUCP (Jim Giles)
Newsgroups: comp.lang.fortran
Subject: Fortran 8x features, generalized precision
Message-ID: <507@a.UUCP>
Date: 4 Mar 88 23:34:45 GMT
Organization: Los Alamos Natl Lab, Los Alamos, N.M.
Lines: 25
Keywords: Fortran, standard review


> The criterion for Fortran 8x features (in my opinion) should be to
> certify existing practice or to extend the language in a significant
> way.  I will use this criterion throughout this discussion.

Generalized precision is not a feature that should be included in Fortran.
No Fortran compiler I'm aware of uses this feature in any form, so the
'existing practice' test fails.

Generalized precision does not add any new functionality either.  Most
implementations will continue to support only SINGLE and DOUBLE precision
and will map the generalized precision variables to one or the other.
This is true because most hardware will continue to possess only one
or two precisions, and implementors will not wish to build more than
one extended format in software.  The use of generalized precision will only
lead to confusion among unsophisticated users as to the inconsistent
behaviour of their codes (with respect to speed) when they port between
machines.

The new intrinsic procedures for getting environmental information about
the arithmetic should be left in the new standard.  This is really an
example of certifying existing practice, since I've never seen a Fortran
support library without some 'machine epsilon' type calls available.

J. Giles
Los Alamos