Re: [sage-support] construction of a number field -- via QQbar?

2015-11-10 Thread Pierre
Oh yes, refreshing the page in my browser revealed that the computation was in fact over. I don't get the same minimal polynomial: Number Field in a with defining polynomial y^64 - 16*y^63 + 120*y^62 - 552*y^61 + 1060*y^60 + 9192*y^59 - 109548*y^58 + 594136*y^57 - 1818336*y^56 + 1418016*y^55 +

Re: [sage-support] construction of a number field -- via QQbar?

2015-11-10 Thread Pierre
Thank Vincent ! I've tried to do it your way, but it is still computing after more than an hour (unless my SageMathCloud page needs refreshing, I'm always confused about that...) How long did it take for you? (you've erased the output of the %time command, i think) On Tuesday, November 10, 201

Re: [sage-support] construction of a number field -- via QQbar?

2015-11-10 Thread Vincent Delecroix
On 10/11/15 10:45, John Cremona wrote: Two ideas: (1) As in your first construction but replace each field constructed after the forst with the corresponding absolute field. (2) Let a = sqrt(2)+sqrt(3)+... as a real number and use LLL to find its mimimum polynomial. (2) is easily done in Sage

Re: [sage-support] construction of a number field -- via QQbar?

2015-11-10 Thread Vincent Delecroix
Hi, This computation takes long time but Sage is able to do it. Doing it step by step, you can observe the relation between the degree of the field and the time needed to generate it. sage: a=2 sage: b=-1 sage: c=5 sage: ra = QQbar(a).sqrt(); ra.exactify() sage: rb = QQbar(b).sqrt(); rb.exact

Re: [sage-support] construction of a number field -- via QQbar?

2015-11-10 Thread Pierre
> > > (1) As in your first construction but replace each field constructed > after the forst with the corresponding absolute field. > > I have tried this but got something like: F0.= NumberField(x^2 - 2) F1.= F0.extension( polygen(F0)^2 - 5 ) L= F1.absolute_field("bar") L(foo0) ... TypeError:

Re: [sage-support] construction of a number field -- via QQbar?

2015-11-10 Thread John Cremona
Two ideas: (1) As in your first construction but replace each field constructed after the forst with the corresponding absolute field. (2) Let a = sqrt(2)+sqrt(3)+... as a real number and use LLL to find its mimimum polynomial. John Cremona On 10 November 2015 at 06:35, Pierre wrote: > Hi, > >

[sage-support] construction of a number field -- via QQbar?

2015-11-10 Thread Pierre
Hi, I'm trying to construct a certain number field, of degree 64 over QQ (well, I'd like to check that using Sage !). It is constructed by adding a certain number of square roots. I have first tried F0= QQ F1.= F0.extension( polygen(F0)^2 - 2) ## adding sqrt(2) F2.= F1.extension( polygen(F1)^2