#11608: RDF/CDF eigenvalues: symmetric matrices, multiplicities
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Reporter: rbeezer | Owner: jason, was
Type: enhancement | Status: needs_work
Priority: minor | Milestone: sage-5.0
Component: linear algebra | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers: Volker Braun
Authors: Rob Beezer | Merged in:
Dependencies: | Stopgaps:
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Changes (by vbraun):
* status: needs_review => needs_work
* reviewer: => Volker Braun
Comment:
On Fedora 16 x86_64, I get
{{{
sage -t devel/sage-main/sage/matrix/matrix_double_dense.pyx
**********************************************************************
File "/home/vbraun/opt/sage-5.0.rc0/devel/sage-
main/sage/matrix/matrix_double_dense.pyx", line 1570:
sage: A.eigenvalues(algorithm='symmetric', tol=1.0e-20)
Expected:
[(-2.0, 1), (-2.0, 2), (-2.0, 1), (1.0, 1), (1.0, 1), (1.0, 1), (1.0,
1), (1.0, 1), (3.0, 1)]
Got:
[(-2.0, 1), (-2.0, 2), (-2.0, 1), (1.0, 1), (1.0, 1), (1.0, 2), (1.0,
1), (3.0, 1)]
}}}
ATLAS is from Fedora, CPU is a Sandy-Bridge i7 quad-core.
Minor nitpicks while we are at it:
* Can you return a tuple (=immutable) instead of a list?
* the symmetric docstring, how about: "converts `self` to a real matrix
and applies the algorithm for Hermitian matrices". Note: technically you
convert (explicit), not coerce (implicit).
* in the hermitian docstring, how about: "uses the
:meth:`~scipy.linalg.eigh` method from !SciPy, which applies only to real
symmetric or complex Hermitian matrices. Since...". This would make it
clear that the `syevr` implementation is used if possible.
* the ".. warning::" block is not indented, so it is not typeset
correctly.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11608#comment:8>
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