On 2014-06-18, William Stein <wst...@gmail.com> wrote: > On Jun 18, 2014 2:22 AM, "Dima Pasechnik" <dimp...@gmail.com> wrote: >> >> On 2014-06-18, 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 >> >> before resorting to calling pari, some supposedly fast things >> are tried (just have a look at n.factor??) >> So one of these things fails. >> >> There are further annoyign things here: >> proof=None in the parameters while the docstring says that the >> default is proof=True >> > > Proof=none means "honor the global proof object settings", which defaults > to true.
It might be terribly confusing to uninitiated. For people exposed to complexity theory, "proof" sounds like computing a primality certificate (e.g. http://en.wikipedia.org/wiki/Primality_certificate#Pratt_certificates) for each prime involved, etc. One has to dig into the FLINT manual to see that proof=True ('proved' in docs of 'n_factor') just means that the primes in the output are prime from the point of view of FLINT's deterministic tests rather than probabilistic ones. > >> n.factor(proof=True) still returns >> 2007193456621 >> >> >> -- >> 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.
