Re: Aw: Re: ispseudoprime speed-up

[Charles Greathouse <crgreathouse@gmail.com>]

Surely this should be a flag to ispseudoprime, not another function?

On Tue, Oct 27, 2026 at 10:55 AM Bill Allombert <Bill.Allombert@math.u-bordeaux.fr> wrote:

On Tue, Oct 27, 2026 at 02:23:42PM +0000, Paul Underwood wrote:
> <html><body><div style="font-family: 'verdana'; font-size: 12px; color: #000;"><span style="background-color: #ffffff;">Yes I forgot to <span style="background-color: #ffffff;">test for</span> even numbers.</span></div>

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ispseudoprime is garanteed up to 2^64
(https://www.cecm.sfu.ca/Pseudoprimes/index-2-to-64.html)
This is a very useful property.

Is your test proven up to sme bound ?

But fundamentally we need two functions
ispseudoprime(p) when we expect p to be prime
isnotpseudoprime(n) when we expect n to be composite.

For example

? n=2^12800+7;
? ispseudoprime(n)
%12 = 0
  ***   last result: cpu time 310 ms, real time 310 ms.
? tstwbar2(n)
%13 = 0
  ***   last result: cpu time 703 ms, real time 705 ms.

Cheers,
Bill.