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RE: [Caml-list] Efficient and canonical set representation?
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Date: 2003-11-10 (20:22)
From: Christophe Raffalli <christophe.raffalli@u...>
Subject: Re: [Caml-list] Rounding mode
Eric Dahlman wrote:
> Christophe Raffalli wrote:
>> I saw a previous discussion about rounding mode for OCaml (in 2000).
>> As anyone implemented the functions to change the rounding mode for 
>> floating point from OCaml (possibly as a patch to add primitives and 
>> save a C function call) ?
>> This is necessary to implement interval arithmetic ...
> Somewhat off topic but why is this necessary from a numerical math type 
> of perspective.  I am honestly curious as I don't see how this would 
> interact with the calculation in a meaningful way.
> -Eric

interval arithmetic proceeds by computing not one appriximation of a 
real number x but an interval containing x. To add two intervals, you 
need to add both ends ... but one end with near to plus infinity round 
and the other end with near to minus infinity (if you care about correct 
program :-).

Christophe Raffalli
Université de Savoie
Batiment Le Chablais, bureau 21
73376 Le Bourget-du-Lac Cedex

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