On Jan 27, 2009, at 12:54 AM, William Stein wrote:
> > On Tue, Jan 27, 2009 at 12:45 AM, alia hamieh > <[email protected]> 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)) - Robert --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
