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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: Fri, 1 May 2015 09:45:13 +0200
Organization: cbb software GmbH
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Date: 2015-05-01T09:45:13+02:00
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On Fri, 01 May 2015 02:32:27 -0500, Nasser M. Abbasi wrote:

> Actually, it is much more complicated. The way I wrote it
> above is not the optimal way. One is supposed to call
> SELECTED_REAL_KIND(n,e) requesting n significant digits
> and e number of digits in the exponent (e is optional).

Huh, they finally learned something after half of a century! (:-))

> i.e. one is supposed to write
> 
> SELECTED_REAL_KIND(8,3)  specifies real type of
> (+-) 0.xxxxxxxx * 10 ^(+-)xxx
> 
> If the compiler does not support this, then the compile
> will fail. This is in a way similar to Ada's
> 
>     type my_type is digits n;

Yes, though Ada also mandates that for the precision specified, the
implementation must guarantee certain accuracy of operations. Maybe in the
following 50 years FORTRAN will get that idea as well.

> And it is supposed to be portable way of doing things, vs.
> using Real*16.

Actually REAL*16 is exactly portable. The problem addressed is not
portability, it is rather design being driven by requirements from the
problem space rather than from implementation specific aspects.

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