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Special Linear Group

asked 2016-05-21 17:44:14 -0600

Ricardo gravatar image

Hello! I am having some trouble getting the list of matrices of the group SL of order 2. When I do these calculations: G=SL(2,GF(3)) print(list(G)) I get the list of elements of the special linear group or order 2 over the finite field of size 3. However, when I try G=SL(2,GF(4)) print(list(G)) the matrices appear with "z2" in them. I have noticed that this happens when the size of the field is not prime, but I don't know how to get past it.

Thank you in advance.

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answered 2016-05-22 03:27:33 -0600

tmonteil gravatar image

In a finite field with prime cardinality, every element can be expressed (by sum or products) by using only 1, the unit of the field. In a finite field with non-prime cardinality, it is not possible anymore since 1 will only generate the smaller subfield of prime cardinality. So, you need another element (called a "generator" of the field) to generate the whole field. This is the z2 you got:

sage: F = GF(4)
sage: F.gen()

If you want to use z2 in your computations, you should attribute it the Python name z2:

sage: z2
NameError: name 'z2' is not defined
sage: F.inject_variables()
Defining z2
sage: z2
sage: z2^2
z2 + 1
sage: z2^3
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Asked: 2016-05-21 17:44:14 -0600

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Last updated: May 22 '16