Re: keep flag=1 recursively in isprime

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

* Bill Allombert [2015-05-24 17:37]:
> On Tue, May 05, 2015 at 10:53:11PM +0200, Pascal Molin wrote:
> > isprime(p,1) calls Pocklington-Lehmer only at the first recursion level and
> > then
> > falls back to the check_prime rountine which may call APRCL.
> > 
> > Looking at the code I assume this is intentional but I find it misleading.
> > I would prefer if the flag were kept recursively, or suggest having a
> > stronger flag ensuring to use only the PL test -- in particular the
> > returned certificate would never contain '2'.
> 
> This is not really practical. However, what should be done is
> for check_prime to use the same criterion as BPSW_isprime_big,
> instead of simply (expi(p) <= 250), otherwise
> 
> *  2  if x is a large prime whose primality could only sensibly be
> proven  (given the algorithms implemented in PARI) using the APRCL
> test.
> 
> is a white lie.

Done in 'master' branch.

Cheers,

    K.B.

P.S. A combined N^2-1 test (N-1 & N+1) is still of interest... 
--
Karim Belabas, IMB (UMR 5251)  Tel: (+33) (0)5 40 00 26 17
Universite de Bordeaux         Fax: (+33) (0)5 40 00 69 50
351, cours de la Liberation    http://www.math.u-bordeaux.fr/~kbelabas/
F-33405 Talence (France)       http://pari.math.u-bordeaux.fr/  [PARI/GP]
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