On Thu, 13 Sep 2018 at 13:42, Erik Bray <erik.m.b...@gmail.com> wrote:
> Hi all, > > This class has a doctest that is failing on Python 3, and it's not > clear to me whether the bug is really in the code, or the test itself. > > The test that's failing is: > > sage: R.<x> = QQ[] > sage: V = span(R,[[x,1+x],[x^2,2+x]]) > sage: W = RR^2 > I expect that is a typo for W=R^2. Otherwise, as you say, it is a nonsensical comparison. > sage: from sage.modules.free_module import EchelonMatrixKey > sage: V = EchelonMatrixKey(V) > sage: W = EchelonMatrixKey(W) > sage: V < W > True > It certainly should not return True here: as it is a nonsensical comparison some kind of ValueError seems better than False though. > > It doesn't really make a lot of sense, because this ends up calling > FreeModule_ambient._echelon_matrix_richcmp(V, W). The two arguments > happen to have the same rank, but different base rings neither of > which are subrings of each other (specifically, fraction field of > polynomials over QQ, and Real Field with 53 bits precision). > > The code ends up just comparing the base fields with <, which on > Python 2 "works" because it falls back on nonsensical defaults, but on > Python 3 this (expectedly) crashes with a TypeError. > > However, reading the documentation for EchelonMatrixKey and > echelon_matrix_richcmp gives me the impression that this nonsensical > comparison isn't really the right behavior in the first place, but I'm > not sure. Any experts on this code want to weight in? > > -- > 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.
