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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: getting same output as gfortran, long_float
Date: Mon, 4 May 2015 09:21:31 +0200
Organization: cbb software GmbH
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Date: 2015-05-04T09:21:31+02:00
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On Sun, 3 May 2015 17:15:15 -0700 (PDT), robin.vowels@gmail.com wrote:

> On Friday, May 1, 2015 at 5:45:23 PM UTC+10, Dmitry A. Kazakov wrote:

>> Actually REAL*16 is exactly portable.
> 
> No it's not.
> Some compilers treat that is an error.

Portability applies to compilable programs only. You could not compile

   type X is mod 2**64;

either. That does not make it non-portable, IMO.

Portable means: The program exposes same [logically relevant] behavior on
all platforms [of interest].

A program that does not compile on a platform of interest is just an
illegal program. It is neither portable or non-portable. We don't know yet.

> That form is non-standard.

Maybe. Though "FORTRAN" and "standard" sound silly in the same context.

> SELECTED_REAL_KIND or a similar modern form is how
> precision may be specified in a portable manner.

Maybe, but not for the reason of being standard or compilable. The point
was about specifying precision [and accuracy] in the problem space terms
rather than in machine-specific ones.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de