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From: Brian Drummond <brian@shapes.demon.co.uk>
Newsgroups: comp.lang.ada
Subject: Re: REAL
Date: Wed, 14 Mar 2012 20:37:28 +0000 (UTC)
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Date: 2012-03-14T20:37:28+00:00
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On Wed, 14 Mar 2012 14:51:59 +0100, Dmitry A. Kazakov wrote:

> Interval arithmetic does not compute anything differently. It just keeps
> track of the error bounds.
> 
> The disadvantages comparing to normal arithmetic is 
(paraphrasing : a factor of two in hardware may not be very important, 
but...)
> Comparing to analytical methods of error estimation. Intervals give a
> pessimistic one. 

Indeed. As has been pointed out frequently on comp.arch by (I think) Nick 
Maclaren, any sufficiently complex calculation in interval arithmetic 
will return the interval (-inf, +inf).

> A manual analysis based on additional knowledge
> (especially if variables are dependant) may sufficiently improve the
> estimation. 

But surely the same analysis can be performed on float arithmetic - 
admittedly this time, to widen the estimated range.

- Brian