Re: Finding bitness of gp

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

* 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/