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Polynomial ring with complex elements.

asked 3 years ago

kev gravatar image

updated 3 years ago

I am trying to define the polynomial ring Z[j] where j is a primitive 3rd root of unity, i.e. j=e23πiC.

I tried this:

P.<x> = PolynomialRing(QQ)
j = exp((2/3)*pi*i)
P[j]

But I get the error:

NotImplementedError: ring extension with prescribed embedding is not implemented
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answered 3 years ago

slelievre gravatar image

The ring you need is the ring of Eisenstein integers.

It is implemented in Sage as EisensteinIntegers().

Try this:

sage: P.<j> = EisensteinIntegers()

sage: P
Eisenstein Integers in Number Field in j with defining polynomial x^2 + x + 1 with j = -0.50000000000000000? + 0.866025403784439?*I

sage: j
j
sage: j^2
-j - 1
sage: j^3
1
sage: 1 + j + j^2
0
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Comments

Thanks! Is it possible to express Z[j](25j) as well? I tried P.quotient((2-5*j)), but I am getting IndexError: the number of names must equal the number of generators.

kev gravatar imagekev ( 3 years ago )

What is Z[j]25j ?

Max Alekseyev gravatar imageMax Alekseyev ( 3 years ago )

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Asked: 3 years ago

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Last updated: Dec 06 '21