#18365: Definition of LU descomposition of a matrix depends on the base ring
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Reporter: tmonteil | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.7
Component: linear algebra | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by tmonteil):
It is worth noticing that the source code for matrices over `RDF` calls
`scipy.linalg.lu` which returns a triple `(P,L,U)` such that `A=PLU` and
then transpose `P` with the documentation:
{{{
# Numpy has a different convention than we had with GSL
# So we invert (transpose) the P to match our prior behavior
# TODO: It's an awful waste to store a huge matrix for P, which
# is just a simple permutation, really.
}}}
So, i guess this extra transposition should be reverted, so that it
becomes consistent with both `scipy` and the implementation for exact
rings.
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Ticket URL: <http://trac.sagemath.org/ticket/18365#comment:1>
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