Thank you very much, it woks perfectly.
Samuele

2010/4/19 luisfe <[email protected]>:
>
>
> On 19 abr, 12:07, "samuele.anni" <[email protected]> wrote:
>> Hello,
>> I'm trying to implement an algorithm for complete my thesis work about
>> congruence between modular forms and Galois representation.
>> A step of the algorithm I am working on consists in replacing a
>> generator of the number field with a fixed value obtained, clearly the
>> command substitute cannot work because the elements of the matrix are
>> algebraic integers of the number field so nothing is seen as a
>> “variable”. The only thing that comes in my mind is to find a way to
>> convert my vector into a polynomial vector substituing to alpha a
>> variable x, but I cannot find a way to do this.
>>
>> >>sage: K.<alpha> = NumberField(x^4 - 30*x^2 - 40*x + 5);K
>>
>> Number Field in alpha with defining polynomial x^4 - 30*x^2 - 40*x + 5
>>
>> >>sage: A=[alpha - 1, 1/2*alpha^3 - 5/2*alpha^2 - 1/2*alpha + 17/2, -alpha^3 
>> >>+4*alpha^2 + alpha - 10, alpha^2 - 2*alpha - 3, 2*alpha^3 - 8*alpha^2 
>> >>-4*alpha + 22, -2*alpha^3 + 8*alpha^2 + 2*alpha - 18, -2*alpha^3 
>> >>+8*alpha^2 + 3*alpha - 21, 3/2*alpha^3 - 15/2*alpha^2 + 3/2*alpha + 
>> >>33/2,-3/2*alpha^3 + 11/2*alpha^2 + 7/2*alpha - 27/2, 2*alpha^3 - 7*alpha^2 
>> >>-4*alpha + 15, -1/2*alpha^3 + 1/2*alpha^2 + 5/2*alpha - 1/2, -alpha^3 
>> >>+6*alpha^2 - alpha - 16, -alpha^3 + 3*alpha^2 + 6*alpha - 12, 3/2*alpha^3- 
>> >>11/2*alpha^2 - 5/2*alpha + 21/2, -3*alpha^3 + 13*alpha^2 + 5*alpha -35];
>> >>sage: A1=[A[i].substitute(alpha=12) for i in range(0, len(A))];A1
>>
>> [alpha - 1, 1/2*alpha^3 - 5/2*alpha^2 - 1/2*alpha + 17/2, -alpha^3 +
>> 4*alpha^2 + alpha - 10, alpha^2 - 2*alpha - 3, 2*alpha^3 - 8*alpha^2 -
>> 4*alpha + 22, -2*alpha^3 + 8*alpha^2 + 2*alpha - 18, -2*alpha^3 +
>> 8*alpha^2 + 3*alpha - 21, 3/2*alpha^3 - 15/2*alpha^2 + 3/2*alpha +
>> 33/2, -3/2*alpha^3 + 11/2*alpha^2 + 7/2*alpha - 27/2, 2*alpha^3 -
>> 7*alpha^2 - 4*alpha + 15, -1/2*alpha^3 + 1/2*alpha^2 + 5/2*alpha -
>> 1/2, -alpha^3 + 6*alpha^2 - alpha - 16, -alpha^3 + 3*alpha^2 + 6*alpha
>> - 12, 3/2*alpha^3 - 11/2*alpha^2 - 5/2*alpha + 21/2, -3*alpha^3 +
>> 13*alpha^2 + 5*alpha - 35]
>>
>> Does anybody know a way to solve my problem?
>> Thanks for the help               Samuele
>
> If x is an element of K, x.polynomial() returns a representation of x
> as a polynomial (the representative of x of minimal degree thinking
> K=QQ[x]/f(x))
>
> So, you can do
>
> sage: A1=[x.polynomial()(12) for x in A];A1
> [11, 1013/2, -1150, 117, 2278, -2298, -2289, 3093/2, -3543/2, 2415,
> -1525/2, -892, -1236, 3561/2, -3287]
>
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