#9760: Possible numerical noise doctest failure in sage/matrix/matrix2.pyx on t2
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Reporter: mpatel | Owner: drkirkby
Type: defect | Status: new
Priority: blocker | Milestone: sage-4.5.3
Component: solaris | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Comment(by mpatel):
For the example starting around line 6393 of `sage/matrix/matrix2.pyx`, I
get this on t2:
{{{
#!python
sage: set_random_seed(0)
sage: r = MatrixSpace(ComplexField(100), 6, 6).random_element()
sage: m = r * r.conjugate().transpose()
sage: m.change_ring(CDF);
sage: eigs = m.change_ring(CDF).eigenvalues()
sage: from sage.misc.citation import get_systems
sage: get_systems('eigs = m.change_ring(CDF).eigenvalues()')
['numpy', 'scipy']
sage: [imag(e) for e in eigs]
[-3.08834127609e-16, 1.137042931e-16, 1.50426489494e-16,
1.64867945474e-16, -4.61662881292e-16, 1.74964827139e-16]
sage: all(imag(e) < 1e-15 for e in eigs)
True
}}}
On sage.math, I get
{{{
#!python
[...]
sage: [imag(e) for e in eigs]
[-4.98835989975e-16, -5.05298436852e-16, 5.59670199836e-17,
4.34508443713e-17, -5.75358699674e-17, 5.1816322259e-16]
sage: sage: all(imag(e) < 1e-15 for e in eigs)
True
}}}
(The real parts of the eigenvalues agree.) I suppose that these are
double-precision computations and that we cannot take the returned
imaginary parts as other than "small"?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9760#comment:2>
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