#18836: Make refine_embedding into a method of number fields instead of
stand-alone
-------------------------------------+-------------------------------------
Reporter: cremona | Owner:
Type: enhancement | Status: needs_work
Priority: minor | Milestone: sage-6.8
Component: number fields | Resolution:
Keywords: | Merged in:
Authors: John Cremona | Reviewers: Vincent Delecroix
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/cremona/18836-refine_embedding | 87e8c14747eb0f5bf9b877b971b2ab2d5edbbffd
Dependencies: | Stopgaps:
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Comment (by cremona):
I did what was asked for (almost) and rebased onto 6.8.beta7. There does
not seem to be a way to ask for one root in a field close to a given
approximation, so it still finds all roots in the higher precision field
-- but only the roots, it does not contruct all teh associated embeddings,
just the closest one. I think the code is less obfuscated now too.
There is still a problem,though: in testing I get two errors (from
essentially the same test) in sage/schemes/elliptic_curves/ell_point.py
and period_lattice.py. These occur when a complex embedding has been
refined to infinite precision (i.e. to an embedding into QQbar), but an
error is caused when an element of QQbar has its square root taken: its
_value is an element of sage.rings.real_mpfi.RealIntervalFieldElement
which is surely wrong -- it should be the corresponding complex type --
and does not like its argument being asked for.
I have not been able to track this down, so I have not set the ticket to
"needs review" as I know that these tests fail, but I am guessing that I
have somehow stumbled across a bug which has nothing to do with this
ticket. Help appreciated!
--
Ticket URL: <http://trac.sagemath.org/ticket/18836#comment:5>
Sage <http://www.sagemath.org>
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