On Tue, Jan 27, 2009 at 1:51 PM, Robert Bradshaw <rober...@math.washington.edu> wrote: > > > On Jan 27, 2009, at 12:54 AM, William Stein wrote: > >> >> On Tue, Jan 27, 2009 at 12:45 AM, alia hamieh >> <aliasham...@gmail.com> wrote: >>> I'm trying to deal with following problem: >>> >>> G=DirichletGroup(75) >>> chi = list(G)[8] >>> I need to compute with expressions such as: chi(2)*sqrt(11) >>> the problem is that we cannot do this multiplication because we have >>> "incompatible" operands, the first belongs to the cyclotomic field >>> of order >>> 20 and the other one belongs to a symbolic ring. >>> Is there a way to fix this problem? >>> >>> alia >> >> You can do the following. It's awkward but it works: >> >> sage: G = DirichletGroup(75) >> sage: chi = list(G)[8] >> sage: K = G.base_ring() >> sage: R.<x> = PolynomialRing(K) >> sage: L.<alpha> = K.extension(x^2 - 11) >> sage: chi(2) * alpha >> zeta20^4*alpha >> >> Here alpha = sqrt(11). >> >> Someday Robert Bradshaw is likely to make your original >> chi(2)*sqrt(11) work. We'll see. > > This would require sqrt(11) to be a number field element rather than > a symbolic expression. For many things I think that would be a good > idea, but it has some drawbacks, like when trying to compute sum(sqrt > (p) for p in primes(1000))
But couldn't doing chi(2) * sqrt(11) coerce chi(2) to the symbolic ring and give the answer there? I think that should make sense, because cyclotomic fields are now equipped with a fixed embedding into C. William --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
