Re: QX_caract

[Karim BELABAS <Karim.Belabas@math.u-psud.fr>]

On Wed, 5 Mar 2003, Bill Allombert wrote:
> Why not use the modular algorithm of ZX_caract directly in QX_caract
> instead of removing the content and calling ZX_caract ?
[...]
> Of course I have not addressed how to implement this, in particular
> how to know we have a sufficiently large modulus.

For this to work, the result needs to be in Z[X], wich is not the current
specification of QX_caract.

Hum. Well, there's no documented specification, and the current behaviour is
already incoherent (one argument is assumed to be integral). So I might as
well assume the result is integral, since it's the only situation
which is of interest here.

...

OK, this is implemented in CVS. The modulus bound is rigorous (~ Hadamard
bound + floating point computation if bound is huge).

I have removed QX_caract: simply some of the ZX_* functions tolerate a
non-integral argument _provided_ the result is integral. As they already did
in fact [ replacing the QX_caract call by ZX_caract would have worked ! ]

I know, all of this needs to be documented ...

Cheers,

    Karim.
-- 
Karim Belabas                     Tel: (+33) (0)1 69 15 57 48
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