gmp prime testing
06 Nov 2002 18:01:02 +0100
Torbjorn Granlund <firstname.lastname@example.org> writes:
> > > ul mpz_trial_div(mpz_srcptr N , ul start , ul stop)
> > Sounds fair to me, if Torbjorn likes it.
> Might make sense. What is it supposed to return?
> Any factor, or 1 (or 0?) if no factor is found.
If any reasonable implementation will compute a factor, I'd say return
that factor or 0 if none was found. I think the trivial factors, i.e.
1 and N, should never be returned.
If it's easy to make some additional guarantees (say, that if ul == 2,
then the returned factor will be a multiple of the smallest prime
factor) then that would be nice too, but I don't know if a
smallest-primefactor-of function is really useful.