#11248: SVD matrix decomposition may return a non-invertible "unitary" matrix
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Reporter: rbeezer | Owner: jason, was
Type: defect | Status: new
Priority: major | Milestone: sage-4.7
Component: linear algebra | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Comment(by slabbe):
> If you want to try the Sage (long) one-line command above and see how
prevalent this is, that would also be very helpful.
I just ran the one-liner thousands of time and always get True:
{{{
sage: for _ in range(1000):
A = (random_matrix(ZZ, 4, 8) + I*random_matrix(ZZ, 4, 8)); B =
A.change_ring(CDF); U,S,V = B.SVD();
if not (U.is_unitary() and V.is_unitary()):
print A
....:
sage:
}}}
I also tried dimensions 8 by 16. Do you want me to test something else?
Sébastien
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11248#comment:6>
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