#15027: Inconsistent primitive_root_of_unity for number fields
------------------------------+-------------------------------------
Reporter: cremona | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-5.12
Component: number fields | Keywords: number field unit
Merged in: | Authors:
Reviewers: | Report Upstream: N/A
Work issues: | Branch:
Dependencies: | Stopgaps:
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In 5.11.rc0:
{{{
sage: K = QuadraticField(-3)
sage: K.primitive_root_of_unity()
1/2*a + 1/2
sage: UK = K.unit_group()
sage: K.primitive_root_of_unity()
u
sage: K.primitive_root_of_unity().value()
-1/2*a + 1/2
}}}
In the first call since the unit group has not yet been computed and
cached, a fundamental torsion unit is computed idrectly (using pari). In
the second case it is obtained from the cached unit group, but should have
value() applied to convert from an abstract element of the unit group to
an actual number field element.
This can be fixed with a one-line edit to line 5526 of number_field.py.
--
Ticket URL: <http://trac.sagemath.org/ticket/15027>
Sage <http://www.sagemath.org>
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