On Sat, Mar 20, 2010 at 04:35:01PM +0100, Florent hivert wrote:
> Hi There,
>
> > In order to let Rob use IntegerModRing(n) as example of finite
> > additive group for his cool Cayley graph feature (#7555), I just wrote
> > a patch (#8562) letting IntegerModRing(n) use the category
> > framework. That was essentially a one liner, plus minor updates here
> > and there, and all test pass.
>
> [...]
>
>
> > The Mod call constructs IntegerModRing(2^9941) and the primality test
> > triggers a timeout or pari overflow.
> >
> > What strategy would you recommend?
> >
> > (1) We don't care about the usecase above (hmm)
> >
> > (2) IntegerModRing(n) is always in CommutativeRings()
> >
> > (3) Same thing, unless the user specifies the category:
> >
> > IntegerModRing(5, Fields())
>
> You probably mean
> IntegerModRing(5, category=Fields())
> which is consitent with was we do in sevaral other places.
Yes.
> > Although in that case, he might as well call GF(5).
> >
> > (4) IntegerModRing(n) always do a primality test, unless the user
> > specifies himself the category.
> >
> > (5) When n is not too big, IntegerModRing(n) checks the primality of
> > n, and sets the category accordingly. Otherwise it always uses
> > CommutativeRings().
> >
> > (6) When n is not too big, IntegerModRing(n) checks the primality of
> > n, and returns GF(n) or a plain IntegerModRing(n) accordingly.
>
> What about:
>
> (6') if the user specifies a category with
> IntegerModRing(5, category=Fields())
> then trust him and do no check otherwise (6). But maybe it is what you meant.
That would be a 5', but yes indeed.
Cheers,
Nicolas
--
Nicolas M. Thiéry "Isil" <nthi...@users.sf.net>
http://Nicolas.Thiery.name/
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