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Newsgroups: comp.lang.ada
Date: Wed, 2 Mar 2016 06:11:19 -0800 (PST)
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Subject: Re: Everything You Know Is Wrong
From: vincent.diemunsch@gmail.com
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Xref: news.eternal-september.org comp.lang.ada:29644
Date: 2016-03-02T06:11:19-08:00
List-Id: <comp.lang.ada>

Le lundi 29 f=E9vrier 2016 13:14:09 UTC+1, Jacob Sparre Andersen a =E9crit =
:

> Some of the rules which (apparently) aren't wrong yet:
>=20
>    http://www.cse.msu.edu/~cse320/Documents/FloatingPoint.pdf
>=20
> Greetings,
>=20
> Jacob

Very interesting !=20
Here is the point about Ada :=20

Remarkably enough, some languages don't clearly specify that if x is a
floating-point variable (with say a value of 3.0/10.0), then every occurren=
ce
of (say) 10.0*x must have the same value. For example Ada, which is based
on Brown's model, seems to imply that floating-point arithmetic only has to
satisfy Brown's axioms, and thus expressions can have one of many possible
values. Thinking about floating-point in this fuzzy way stands in sharp
contrast to the IEEE model, where the result of each floating-point operati=
on is
precisely defined. In the IEEE model, we can prove that (3.0/10.0)*10.0
evaluates to 3 (Theorem 7). In Brown's model, we cannot.

Maybe this could be a topic for a new revision of Ada ?

Kind regards,

Vincent