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Karim Belabas on Mon, 25 Dec 2023 20:53:34 +0100
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Re: Finding bitness of gp
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- To: Ilya Zakharevich <nospam-abuse@ilyaz.org>
- Subject: Re: Finding bitness of gp
- From: Karim Belabas <Karim.Belabas@math.u-bordeaux.fr>
- Date: Mon, 25 Dec 2023 20:53:29 +0100
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* Ilya Zakharevich [2023-12-25 17:04]:
> On Sun, Dec 24, 2023 at 10:28:03PM -0800, Ilya Zakharevich wrote:
> > On Tue, Dec 19, 2023 at 10:50:26AM +0100, Bill Allombert wrote:
> > > > Should not there be O(1) way to find the current localbitprecision()?
> >
> > > Yes, it is called getlocalbitprec().
> >
> > As you could see from this mail thread, this name is not discoverable.¹⁾
>
> Another missing (or not discoverable) piece of info: bitness of gp.
> It seems to be silly (and very slow with high \p) to do
>
> (08:01) gp > bitprecision(bitprecision(1.,1))
> %2142 = 64
It's documented in develop.tex that
sizebyte(0)==16
can (and, for now, should) be used to detect 64-bit arch. And
sizebyte(0)==8
for 32 bits.
Cheers,
K.B.
--
Pr. Karim Belabas, U. Bordeaux, Vice-président en charge du Numérique
Institut de Mathématiques de Bordeaux UMR 5251 - (+33) 05 40 00 29 77
http://www.math.u-bordeaux.fr/~kbelabas/