On Saturday, April 24, 2021 at 1:33:36 AM UTC+2 slelievre wrote: > Could this have to do with one of the following existing tickets? > > - Sage Trac ticket 22008 > complex_embedding on relative number fields is inconsistent with the base field > https://trac.sagemath.org/ticket/22008
This is indeed related: it also involves Sage mistaking the extension [L:K] for the extension [L:QQ]. But it does not seem to be the exact same problem: I am not sure that fixing ticket 17524 would automatically fix the problem I am describing here. Well, it *might*; but the only way to be sure is to actually pinpoint the problem - and this would involve a complex hunt through a lot of different code files that I (being a total newbie to Sage development) do not feel like doing right now. > - Sage Trac ticket 17524 > polynomial for relative number field elements > https://trac.sagemath.org/ticket/17524 This one, OTOH, seems a bit different: in this one, there is no confusion between [L:K] and [L:QQ], but simply a problem of consistency between the chosen embedding of K when taken by itself and the chosen embedding of K when seen as a subfield of L. On Saturday, April 24, 2021 at 9:51:27 PM UTC+2 vdelecroix wrote: > At least on 9.3.rc4 it is fixed by using instead > > sage: K.<sqrt2> = QuadraticField(2, embedding=AA(2).sqrt()) > sage: L.<s> = K.extension(x^3 + (sqrt2/2 + 1/3)*x^2 + (2*sqrt2/5+3/7)*x - > 1) > sage: phi0 = hom(L, QQbar, roots[0]) > sage: phi1 = hom(L, QQbar, roots[1]) > sage: phi2 = hom(L, QQbar, roots[2]) > sage: phi0(sqrt2) > 1.414213562373095? > sage: phi1(sqrt2) > 1.414213562373095? + 0.?e-17*I > sage: phi2(sqrt2) > 1.414213562373095? + 0.?e-17*I > For what it is worth, in my config (version 9.1), this gives a "ValueError: relations do not all (canonically) map to 0 under map determined by images of generators". So, OK, presumably this has been fixed in the meanwhile. But anyway, where can I find documentation for the "hom" method? Assuming it works, OK, thank you, it is a good workaround. Still, in the meanwhile, I think that something needs to be done about NumberFieldEmbedding: it should either be fixed, be deprecated, or at least the documentation should be updated to signal that it does not work in relative fields. So I guess I will now try to open a ticket. -- 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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-support/867cb177-9e58-4332-88be-b5cd0c9cf5cfn%40googlegroups.com.
