Hello,

I am trying to get matrix groups for the universal cyclotomic field
(which I am currently implementing) working. I encountered two
problems in this context:

1. the method MatrixGroup_gap.list contains the lines

        a = F.prime_subfield().multiplicative_generator()
        b = F.multiplicative_generator()

which is not even defined for QQ, so I guess it would be better to
replace them by

        sage: a = F.prime_subfield()(1)
        sage: b = F(1)

2. the second problem is the line

        v = eval(s, {'a':a, 'b':b})

for the cyclotomic field, I get the following error:

        sage: F = CyclotomicField(4)
        sage: z = F.gen()
        sage: m = matrix(2,[z,0,0,1])
        sage: G = MatrixGroup([m])
        sage: G.list()
------------------------------------------------------------
   File "<string>", line 1
     [[[!-1,!0],[!0,!1]],[[-zeta4,!0],[!0,!1]],[[zeta4,!0],[!0,!1]],[[!
1,!0],[!0,!1]]]
        ^
SyntaxError: invalid syntax

and for the new universal cyclotomic field, elements are written as
E(n), see http://trac.sagemath.org/sage_trac/ticket/8327. Thus, to
solve the problem for the universal cyclotomic field, I would need to
add

        from
sage.rings.universal_cyclotomic_field.universal_cyclotomic_field
import E
        v = eval(s, {'a':a, 'b':b, 'E':E})

Would this be okay, or does that cause further trouble? I don't know
what the problem for the CF is...

Thanks for suggestions, Christian

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