#12850: Fix coercions for CyclotomicField with different embeddings
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       Reporter:  stumpc5           |         Owner:  davidloeffler
           Type:  defect            |        Status:  new          
       Priority:  major             |     Milestone:  sage-5.0     
      Component:  number fields     |    Resolution:               
       Keywords:  cyclotomic field  |   Work issues:               
Report Upstream:  N/A               |     Reviewers:               
        Authors:                    |     Merged in:               
   Dependencies:                    |      Stopgaps:               
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Changes (by stumpc5):

 * cc: nthiery (added)


Old description:

> With the current coercion between cyclotomic fields, we get an non-
> commutative coercion diagram:
>
> {{{
> sage: CF1 = CyclotomicField(5)
> sage: CF2 = CyclotomicField(5,embedding = (4 * CLF.pi() * CLF.gen() /
> 5).exp())
> sage: CC(CF1.gen()-CF2.gen())
> 0
> sage: CC(CF1.gen()) - CC(CF2.gen())
> 1.11803398874989 + 0.363271264002680*I
> }}}

New description:

 With the current coercion between cyclotomic fields, we get an non-
 commutative coercion diagram:

 {{{
 sage: CF1 = CyclotomicField(5)
 sage: CF2 = CyclotomicField(5,embedding = (4 * CLF.pi() * CLF.gen() /
 5).exp())
 sage: CC(CF1.gen()-CF2.gen())
 0
 sage: CC(CF1.gen()) - CC(CF2.gen())
 1.11803398874989 + 0.363271264002680*I
 }}}

 TODO: When this is done, we have to fix the embedding of cyclotomic fields
 into the universal cyclotomic field.

--

-- 
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12850#comment:1>
Sage <http://www.sagemath.org>
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