Ok... not exactly what I said but even simpler. This is #17099 which needs review.
Vincent 2014-10-04 20:31 UTC+02:00, Vincent Delecroix <[email protected]>: > Ok. The bug is in the canonicalize function of QuaternionAlgebra... > the function does not care about 0. This is "very optimized" and "very > wrong" ;-) > > I will provide a ticket in a minute. > > Vincent > > 2014-10-04 20:01 UTC+02:00, Vincent Delecroix <[email protected]>: >> And more precisely a lack of simplification at some point >> >> sage: w[0].denominator() >> 2 >> sage: z[0].denominator() >> 4 >> >> 2014-10-04 19:57 UTC+02:00, Vincent Delecroix >> <[email protected]>: >>> Hello Nathann, >>> >>> Seems to be the comparison in the number field... >>> >>> sage: z[0] >>> -1/2 >>> sage: w[0] >>> -1/2 >>> sage: z[0] == w[0] >>> False >>> sage: z[0].parent() >>> Number Field in a with defining polynomial x^3 + x - 1 >>> sage: w[0].parent() >>> Number Field in a with defining polynomial x^3 + x - 1 >>> >>> Vincent >>> >>> 2014-10-04 19:44 UTC+02:00, Nathan Dunfield <[email protected]>: >>>> There's something wrong with comparison operators for elements of >>>> QuaternionAlgebras defined over a number field. Here's a simple >>>> example, >>>> where first it gives the wrong answer and then, after doing some >>>> arithmetic >>>> >>>> with the elements, a mix of right and wrong answers: >>>> >>>> sage: K = NumberField(x**3 + x - 1, 'a') >>>> sage: D.<i,j,k> = QuaternionAlgebra(K, -1, -3) >>>> sage: x = (i + j)/K(2) >>>> sage: z = (-1 + (i + j) + k)/K(2) - x >>>> sage: w = i * x >>>> sage: w, z >>>> (-1/2 + 1/2*k, -1/2 + 1/2*k) >>>> sage: w == z >>>> False >>>> sage: z == w >>>> False >>>> sage: z - w >>>> 0 >>>> sage: z == w, w == w, z-w == 0 >>>> (True, True, False) >>>> >>>> I looked in trac, but I didn't see this. Is this issue already known, >>>> and, >>>> >>>> if so, is there a simple work-around? >>>> >>>> Thanks, >>>> >>>> Nathan >>>> >>>> -- >>>> 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 [email protected]. >>>> To post to this group, send email to [email protected]. >>>> 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 [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
