Re: [sage-devel] bug in trivial case of number field isomorphism due to wrong pari/sage conversion
On Thu, 13 Dec 2018 at 17:22, John Cremona wrote: > > > On Thu, 13 Dec 2018 at 16:42, Vincent Delecroix <20100.delecr...@gmail.com> > wrote: > >> Le 13/12/2018 à 17:17, Jeroen Demeyer a écrit : >> > On 2018-12-13 13:11, John Cremona wrote: >> >> The problem is that t is a pari gen and Sage tries too hard to compare >> >> that with python 0. >> > >> > This has nothing to do with Sage or Python, the "problem" is that PARI >> > considers [0] and 0 equal. >> >> Which make sense if you think of [0] as a polynomial of degree 0, and >> more generally as the zero vector. Sage does the same to some extent >> >> sage: 0 == vector([0]) >> True >> sage: 0 == QQ['x'].zero() >> True >> >> > Personally, I think that Sage (really the package cypari2 which >> > implements the PARI <-> Python interface) should follow the PARI >> > semantics, even if they are dubious. >> >> +1 >> > > Well that makes fixing this easier since all we need to do is change one > line in the is_isomorphic() method. I assume that you agree that there is > a top-level bug at least! > Some apologies seem to be required since I found the same bug 3 months ago and made a ticket https://trac.sagemath.org/ticket/26239 with exactly the same diagnosis. I had forgotten. Well, at least I don't have to make a new ticket, just fix it. > > 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 https://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 https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
Re: [sage-devel] bug in trivial case of number field isomorphism due to wrong pari/sage conversion
On Thu, 13 Dec 2018 at 16:42, Vincent Delecroix <20100.delecr...@gmail.com> wrote: > Le 13/12/2018 à 17:17, Jeroen Demeyer a écrit : > > On 2018-12-13 13:11, John Cremona wrote: > >> The problem is that t is a pari gen and Sage tries too hard to compare > >> that with python 0. > > > > This has nothing to do with Sage or Python, the "problem" is that PARI > > considers [0] and 0 equal. > > Which make sense if you think of [0] as a polynomial of degree 0, and > more generally as the zero vector. Sage does the same to some extent > > sage: 0 == vector([0]) > True > sage: 0 == QQ['x'].zero() > True > > > Personally, I think that Sage (really the package cypari2 which > > implements the PARI <-> Python interface) should follow the PARI > > semantics, even if they are dubious. > > +1 > Well that makes fixing this easier since all we need to do is change one line in the is_isomorphic() method. I assume that you agree that there is a top-level bug at least! 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 https://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 https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
Re: [sage-devel] bug in trivial case of number field isomorphism due to wrong pari/sage conversion
Le 13/12/2018 à 17:17, Jeroen Demeyer a écrit : On 2018-12-13 13:11, John Cremona wrote: The problem is that t is a pari gen and Sage tries too hard to compare that with python 0. This has nothing to do with Sage or Python, the "problem" is that PARI considers [0] and 0 equal. Which make sense if you think of [0] as a polynomial of degree 0, and more generally as the zero vector. Sage does the same to some extent sage: 0 == vector([0]) True sage: 0 == QQ['x'].zero() True Personally, I think that Sage (really the package cypari2 which implements the PARI <-> Python interface) should follow the PARI semantics, even if they are dubious. +1 -- 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 https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
Re: [sage-devel] bug in trivial case of number field isomorphism due to wrong pari/sage conversion
On 2018-12-13 13:11, John Cremona wrote: The problem is that t is a pari gen and Sage tries too hard to compare that with python 0. This has nothing to do with Sage or Python, the "problem" is that PARI considers [0] and 0 equal. Personally, I think that Sage (really the package cypari2 which implements the PARI <-> Python interface) should follow the PARI semantics, even if they are dubious. -- 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 https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
