#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 jason):
kcrisman: no bug on the intel site. We changed the zgesdd call to "A", so
we needed to print out the full matrix to see the last vector. I think
you just confirmed that the "problem" is in Lapack. Or rather, Lapack is
behaving exactly as the docs say, but the problem is that numpy is
assuming that the V matrix returned is a unitary matrix. It is if
rows>=cols, according to the docs, but if rows<cols, then the return V is
not stated to be a unitary matrix.
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11248#comment:27>
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