#12632: bug comparing trivial Dirichlet characters
------------------------------+---------------------------------------------
Reporter: bober | Owner: was
Type: defect | Status: positive_review
Priority: major | Milestone: sage-5.0
Component: number fields | Keywords:
Work_issues: | Upstream: N/A
Reviewer: Jonathan Bober | Author: David Loeffler
Merged: | Dependencies:
------------------------------+---------------------------------------------
Description changed by bober:
Old description:
> {{{
> sage: G1 = DirichletGroup(4)
> sage: G2 = DirichletGroup(1)
> sage: G2[0] == G1[0].primitive_character()
> [...]
> ZeroDivisionError: Inverse does not exist.
> }}}
>
> (The answer should be {{{True}}}.)
>
> What happens, I think, is that
> {{{G1[0].primitive_character().parent().base_ring()}}} is not the same as
> {{{G2.base_ring()}}} and something somewhere tries to do some coercion,
> and fails:
>
> {{{
> sage: G1[0].primitive_character().parent().base_ring()
> Cyclotomic Field of order 2 and degree 1
> sage: G2.base_ring()
> Cyclotomic Field of order 1 and degree 1
> }}}
New description:
{{{
sage: G1 = DirichletGroup(4)
sage: G2 = DirichletGroup(1)
sage: G2[0] == G1[0].primitive_character()
[...]
ZeroDivisionError: Inverse does not exist.
}}}
(The answer should be {{{True}}}.)
What happens, I think, is that
{{{G1[0].primitive_character().parent().base_ring()}}} is not the same as
{{{G2.base_ring()}}} and something somewhere tries to do some coercion,
and fails:
{{{
sage: G1[0].primitive_character().parent().base_ring()
Cyclotomic Field of order 2 and degree 1
sage: G2.base_ring()
Cyclotomic Field of order 1 and degree 1
}}}
Apply:
- attachment:trac_12632-cyclo_coerce_bug.patch
--
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12632#comment:4>
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