On 18 June 2014 16:49, David Roe <roed.m...@gmail.com> wrote: > We are using flint: > > if mpz_fits_slong_p(n.value): > .... > n_factor(&f, mpz_get_ui(n.value), proof) > > where n_factor is defined in sage.libs.flint.ulong_extras.
Thanks, David -- this explains what is happening (remember that I got this value of n from the flint-dev bug report). I'll ask on flint-dev whether there is an easy patch. Sage seems to be using flint-2.4.3 at the moment. John > > David > > > On Wed, Jun 18, 2014 at 4:28 AM, John Cremona <john.crem...@gmail.com> > wrote: >> >> I noticed an announcement on the flint-dev list which led me to try >> this, and indeed we have the bug: >> >> sage: n=2007193456621 >> sage: n.is_prime() >> False >> sage: n.factor() # !!!!!!!!!! >> 2007193456621 >> sage: pari(n).factor() >> [1001797, 1; 2003593, 1] >> sage: n == 1001797 * 2003593 >> True >> >> See flint-dev for more details, but this seems serious enough to >> report here too. I do not understand why Sage fails to factor n since >> the documentation says that pari is the default, and pari can factor >> this n (as above), however: >> >> sage: n.factor(algorithm='pari') >> 2007193456621 >> >> but >> >> sage: from sage.rings.factorint import factor_using_pari >> sage: factor_using_pari(n) >> [(1001797, 1), (2003593, 1)] >> >> so something is going wrong before pari is getting called, perhaps a >> primality test? >> >> John >> >> -- >> You received this message because you are subscribed to the Google Groups >> "sage-devel" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to sage-devel+unsubscr...@googlegroups.com. >> To post to this group, send email to sage-devel@googlegroups.com. >> Visit this group at http://groups.google.com/group/sage-devel. >> For more options, visit https://groups.google.com/d/optout. > > > -- > You received this message because you are subscribed to the Google Groups > "sage-devel" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sage-devel+unsubscr...@googlegroups.com. > To post to this group, send email to sage-devel@googlegroups.com. > Visit this group at http://groups.google.com/group/sage-devel. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
