[std-interval] nth_root_rel

George Corliss George.Corliss at marquette.edu
Fri Sep 15 07:08:54 PDT 2006


Friends,

I have no first-hand experience to confirm Frédéric Goualard's assertion
about nth_root_rel, but his argument makes sense to me, and I can certainly
underline the importance of providing good support for constraint
propagation.  Constraint propagation is a MAJOR opportunity for reducing
over-estimation we have not yet fully exploited.

On his recommendation, I'd like to see nth_root_rel included.

Dr. George Corliss
Electrical and Computer Engineering
Marquette University
P.O. Box 1881
1515 W. Wisconsin Ave.
Milwaukee, WI 53201-1881
George.Corliss at Marquette.edu
414-288-6599 (office); 288-4400 (GasDay);
    288-6280 (Dept.); 288-5579 (fax)
Office: Haggerty Engineering 296
Www.eng.mu.edu/corlissg


 <Frederic.Goualard at univ-nantes.fr> wrote:

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> Dear Sylvain,
> 
> Sylvain Pion wrote:
>> Guillaume Melquiond wrote:
>>> Le jeudi 14 septembre 2006 à 10:21 +0200, Frédéric Goualard a écrit :
>>> 
>>>> The nth_root_rel() operator does not appear in the standard. Is this
>>>> omission on purpose? If indeed it is, why is it so?
>>> 
>>> The nth_root_rel is purposely out of the proposal because nth_root is
>>> out too :-). I don't think the omission is on purpose though. If people
>>> feel it is useful, it can be added.
>> 
>> Let's be careful with the list of functions, especially those hard
>> to implement.  Having too many may trigger resistance from the C++
>> committee.  I already fear that the changes done in the revision
>> won't be appreciated a lot on that aspect...  But we'll see.
> 
> I agree with you on that. My point is that if nth_root_rel() is not in
> the standard, all relational operators should be discarded as well. As
> far as I understand it, they are mainly of use to interval constraint
> programming, and it makes no sense to be able to handle trigonometric
> constraints while not being able to handle polynomial ones,
> application-wise.
> 
> F.
> - --
> Frédéric Goualard                                 LINA - FRE CNRS 2729
>                            Univ. of Nantes - Ecole des Mines de Nantes
> Tel.: +33 2 51 12 58 38            2, rue de la Houssinière - BP 92208
> Fax.: +33 2 51 12 58 12                         F-44322 NANTES CEDEX 3
> http://goualard.free.fr/
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