#15245: Pfaffian of a skew-symmetric matrix
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Reporter: darij | Owner:
Type: enhancement | Status:
Priority: major | needs_review
Component: combinatorics | Milestone: sage-5.13
Keywords: matrix, sage-combinat, | Resolution:
pfaffian | Merged in:
Authors: Darij Grinberg | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: #14117 | Stopgaps:
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Comment (by darij):
Hi Travis,
thanks once again for the reviews! I fixed all of your issues apart from
not using {{{is_skew_symmetric()}}} because that method doesn't check
diagonal entries to be 0 (it only checks them to satisfy x = -x, which is
not the same in characteristic 2):
{{{
sage: M = Matrix(Zmod(2), [[0,1],[1,1]])
sage: M.is_skew_symmetric()
True
}}}
If you ask me, this is a bug, but I don't want to grasp into yet another
hornet's nest. But thanks for having me look at my check code again; it
contained an ugly indentation error...
I was pretty sure that matrix algorithms are the least busy part of the
code, given how long #14117 took to be reviewed. In hindsight I shouldn't
have done unrelated docstring fixes, but the rook stuff was just pretty
close and caught my eyes.
Best regards,\\
Darij
--
Ticket URL: <http://trac.sagemath.org/ticket/15245#comment:4>
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