#12514: default behavior of matrix([...]).eigenvectors_right() should be sane
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Reporter: ppurka | Owner: jason, was
Type: defect | Status: new
Priority: major | Milestone: sage-5.0
Component: linear algebra | Keywords: matrix eigenvectors
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Comment(by rbeezer):
Replying to [comment:2 ppurka]:
I'd prefer not to default to RDF, perhaps just because somebody enters a
decimal point.
I'm "simulating" that situation below. The output is vastly different
over RDF versus ZZ/QQ. I think it is important that a user understand the
difference, rather than being a victim of behind-the-scenes choices about
which base ring to use when.
{{{
sage: entries = [0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0,
1, 1, 1, 1, 1, 0]
sage: A = matrix(ZZ, 5, 5, entries)
sage: A.eigenvectors_right()
[(4, [
(1, 1, 1, 1, 1)
], 1), (-1, [
(1, 0, 0, 0, -1),
(0, 1, 0, 0, -1),
(0, 0, 1, 0, -1),
(0, 0, 0, 1, -1)
], 4)]
sage: entries[0]=0.0
sage: B = matrix(RDF, 5, 5, entries)
sage: B.eigenvectors_right()
[(-1.0, [(-0.894427191, 0.22360679775, 0.22360679775, 0.22360679775,
0.22360679775)], 1), (4.0, [(0.4472135955, 0.4472135955, 0.4472135955,
0.4472135955, 0.4472135955)], 1), (-1.0, [(-0.498272879122,
-0.290659179488, 0.816613885228, -0.013840913309, -0.013840913309)], 1),
(-1.0, [(-0.279399378114, 0.768348289812, 0.246802784, -0.36787584785,
-0.36787584785)], 1), (-1.0, [(-0.226762156554, -0.132277924656,
-0.0602899384488, -0.438226866039, 0.857556885698)], 1)]
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12514#comment:3>
Sage <http://www.sagemath.org>
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