Re: Factoring small numbers

[Charles Greathouse <charles.greathouse@case.edu>]

(10:46) gp >default(factor_add_primes,0)
(13:51) gp >for(i=1,1000,factor(19180172397815991981))
time = 52,287 ms.

version() gives [2, 8, 0, 16370, "23a2ae3"]. Header is
          GP/PARI CALCULATOR Version 2.8.0 (development 16370-23a2ae3)
           i686 running mingw (ix86/GMP-5.1.3 kernel) 32-bit version
                compiled: Apr 14 2014, gcc version 4.8.2 (GCC)
                            threading engine: single
                 (readline v6.2 enabled, extended help enabled)

Computer is running Windows Vista on an i7. I can give comparative timings on Linux if desired.

Charles Greathouse
Analyst/Programmer
Case Western Reserve University

On Thu, May 8, 2014 at 4:18 PM, Bill Allombert <Bill.Allombert@math.u-bordeaux.fr> wrote:

On Thu, May 08, 2014 at 02:05:38PM -0400, Charles Greathouse wrote:
> Are you sure it's not storing found factors?
>
> removeprimes(setintersect(addprimes(), factor(19180172397815991981)[,1]~));
> default(factor_add_primes,0)
> for(i=1,1000,factor(19180172397815991981))
> ##
>
> I get 52 ms for the factorization, and I don't think my computer is 20
> times slower than yours. (2 or 3 times, maybe.)

Are you using Windows ? pthread ? 32-bit ?

Cheers,
Bill.