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[Octave-bug-tracker] [bug #36104] determinant of a sparse zero matrix
From: |
Marco Caliari |
Subject: |
[Octave-bug-tracker] [bug #36104] determinant of a sparse zero matrix |
Date: |
Thu, 05 Apr 2012 19:39:43 +0000 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686; en-GB; rv:1.9.2.13) Gecko/20101203 Firefox/3.6.13 |
URL:
<http://savannah.gnu.org/bugs/?36104>
Summary: determinant of a sparse zero matrix
Project: GNU Octave
Submitted by: caliari
Submitted on: Thu 05 Apr 2012 19:39:42 GMT
Category: None
Severity: 3 - Normal
Priority: 5 - Normal
Item Group: Incorrect Result
Status: None
Assigned to: None
Originator Name:
Originator Email:
Open/Closed: Open
Discussion Lock: Any
Release: 3.6.0
Operating System: GNU/Linux
_______________________________________________________
Details:
Dear all,
I found the following:
A=sparse(0);
B=sparse(zeros(0,1),zeros(0,1),1,1,1);
A==B
ans = Compressed Column Sparse (rows = 1, cols = 1, nnz = 1 [100%])
(1, 1) -> 1
det(A)
ans = 0
det(B)
error: det: SparseMatrix::determinant symbolic factorization failed
So, A e B are equal, but it is not possible to compute the determinant of B.
The definition of B is weird, I know, but it is precisely what you get from
B = sprand(1,1,0);
This bug is present at least since 3.0.5. By the way, in Matlab A and B
coincides and have the same zero determinant.
Marco
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- [Octave-bug-tracker] [bug #36104] determinant of a sparse zero matrix,
Marco Caliari <=