On Thu, Jan 28, 2021 at 8:33 AM Vincent Delecroix <20100.delecr...@gmail.com> wrote: > > I would say, better to avoid it. That is a personal comment. > > Vincent > > Le 27/01/2021 à 18:48, G. M.-S. a écrit : > > So if I understand you well, "x in P" should not be used for serious work? > > > > Guillermo > > > > On Wed, 27 Jan 2021 at 08:55, Vincent Delecroix <20100.delecr...@gmail.com> > > wrote: > > > >> Oups, I forgot to copy all the relevant input > >> > >> sage: a = 1.9999999999999999 > >> > >> Vincent > >> > >> Le 26/01/2021 à 19:38, G. M.-S. a écrit : > >>> Just out of curiosity: What is "a"? > >>> > >>> Guillermo > >>> > >>> On Tue, 26 Jan 2021 at 09:29, Vincent Delecroix < > >> 20100.delecr...@gmail.com> > >>> wrote: > >>>> > >>>> And what should be thought about "4.0 in ZZ" ? > >>>> > >>>> Even more fun > >>>> > >>>> sage: a in ZZ > >>>> False > >>>> sage: 4 / a in ZZ > >>>> False > >>>> sage: 4.0 / a in ZZ > >>>> True > >>>> > >>>> Does Sage even have any clear specification for "x in P"?
Certainly. This is just Python: https://docs.python.org/3/reference/expressions.html#membership-test-operations Specifically, you can explore how "in" is implemented for a concrete class P by instpecting P.__contains__?? E.g. to get an idea about puzzling behaviour of ZZ look at (very short) code in ZZ.__contains__?? I don't see why you should avoid it. (You can avoid Python/Sage completely, surely, but this is just Python code, there is no weird magic there) > >>>> > >>>> Concerning input that are of the wrong type, it is common > >>>> in Python (?) to just throw error > >>>> > >>>> >>> list(range(4)) > >>>> [0, 1, 2, 3] > >>>> >>> list(range(4.0)) > >>>> Traceback (most recent call last): > >>>> ... > >>>> TypeError: 'float' object cannot be interpreted as an integer > >>>> > >>>> Vincent > >> > > > > -- > You received this message because you are subscribed to the Google Groups > "sage-support" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sage-support+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sage-support/693740a1-0110-1c28-eeda-a3635b06e36c%40gmail.com. -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-support/CAAWYfq38EKcCzOgyKF8a1CcnfmNK_5BhbKi3MtPnRJmosrdE9g%40mail.gmail.com.
