#12208: LU decomposition gives wrong results on cyclotomic matrices (MacOSX-
specific)
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Reporter: dimpase | Owner: jason, was
Type: defect | Status: needs_info
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 dimpase):
Replying to [comment:10 rbeezer]:
> Replying to [comment:9 dimpase]:
>
> Dima - excellent detective work. And excellent timing, I was just
sitting down to look at this again.
>
> > By the way, if I replace {{{max_entry = zero}}} on line 9334 with
{{{max_entry = zero.abs()}}} then the code works, as this does the right
type of coersion.
> >
> > Overall, this looks like a bug in number fields part of Sage one has
to dig up.
>
> I like the idea of applying {{{abs()}}} to the zero element to get the
types to line up. I will watch the sage-devel thread to see what
transpires, and then write a short patch, likely with your example from
above as a test.
>
Hi Rob,
if abs() is only used to select pivots, it should be perfectly all right
to do so.
This would be a 1-line patch then.
Dima
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12208#comment:11>
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