Re: Why does factorint() take 128ms for 1853 decimal digit prime, while isprime() takes 16:45min/2min cpu/real time?

[hermann@stamm-wilbrandt.de]

On 2026-02-24 00:24, Aurel Page wrote:
> Dear Hermann,
>
> That is because by default, factor does not prove that the factors are
> prime. They are only guaranteed to be pseudoprimes.
> ...
> You can use default(factor_proven, 1) to change this behaviour.
>
> Best,
> Aurel
Thanks Aurel,

while my previous questions were OK, my last question was not.

default(factor_proven, 1) is discussed in 3.8.1 of doc:
https://pari.math.u-bordeaux.fr/pub/pari/manuals/2.17.2/users.pdf#page=177

But I should have learned about it myself easily with "??factorint".

Regards,

Hermann.