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From: "Grein, Christoph" <christoph.grein@eurocopter.com>
Newsgroups: comp.lang.ada
Subject: Re: Interval arithmetic in Ada?
Date: Mon, 22 Apr 2002 15:21:17 +0200 (MET DST)
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Date: 2002-04-22T15:21:17+02:00

> From: "Dmitry A.Kazakov" <mailbox@dmitry-kazakov.de>
>> On Mon, 22 Apr 2002 11:13:10 +0200 (MET DST), "Grein, Christoph"
> <christoph.grein@eurocopter.com> wrote:
> 
> >This was the Ada 83 floating point model.
> 
> Hmm. Interval arithmetic is defined on intervals of numbers as opposed
> to single numbers. It goes approximately like this:
> 
> [a,b] + [c,d] = [a+c, b+d]
> [a,b] * [c,d] = [min (ac, ad, bc, bd), max (ac, ad, bc, bd)]
> ...
> 
> Usually it is used for numeric computations with an automatic control
> over calculation errors. It is also tightly related with the
> possibility theory, fuzzy numbers etc. It is relatively
> straightforward, but firstly I do not want to reinvent wheel and
> secondly it requires precise control over rounding. I feel myself not
> very confident with Annexes A.5 and G.

Again, this _is_ the Ada 83 model with a and b the model numbers enclosing the 
actual value. See the Ada 83 RM.