#12208: LU decomposition gives wrong results on cyclotomic matrices (MacOSX-
specific)
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Reporter: dimpase | Owner: jason, was
Type: defect | Status: new
Priority: major | Milestone: sage-4.8
Component: linear algebra | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Comment(by rbeezer):
Replying to [comment:6 rbeezer]:
> Or maybe there is a better function to be using for the "magnitude" of
an element of an arbitrary ring/field? Maybe a question for sage-devel -
I can't think of the answer.
Answering my own question. Maybe the {{{norm()}}} function (or method) is
a better choice. For a negative rational, it returns the negative value,
which I find odd (but maybe appropriate?).
With test patch, I only get one doctest failure (a permutation matrix
changes) and the original example still gives the same {{{U}}} matrix.
Dima - would you like to try out the test patch (built on 4.8.alpha3)?
I'm not sure yet it is the best solution, but it could be.
Rob
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12208#comment:7>
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