
From:  David Bateman 
Subject:  Re: indexed assignment for sparse matrices in ov2.9.4 
Date:  Thu, 19 Jan 2006 17:29:00 +0100 
Useragent:  Mozilla Thunderbird 1.0.2 (Windows/20050317) 
Thomas Kasper a écrit :
Firstly, you should use speye(n) rather than sparse(eye(n)) as the full nbyn matrix is created and then destroyed with the second form and this poses memory issues with large sparse matrices..Hi, I have a problem with indexed assignment for sparse matrices in octave2.9.4. See below for an example: octave:1> version ans = 2.9.4 octave:2> a = sparse(eye(3)) a = Compressed Column Sparse (rows = 3, cols = 3, nnz = 3) (1, 1) > 1 (2, 2) > 1 (3, 3) > 1 octave:3> a(:,[3,2,1]) = a a = Compressed Column Sparse (rows = 3, cols = 3, nnz = 3) (1, 1) > 1 (2, 2) > 1 (3, 3) > 1
Yes this is a bug, and it has already been fixed in the CVS. With the current CVS I get
octave:4> a = speye(3) a = Compressed Column Sparse (rows = 3, cols = 3, nnz = 3) (1, 1) > 1 (2, 2) > 1 (3, 3) > 1 octave:5> a(:,[3,2,1]) ans = Compressed Column Sparse (rows = 3, cols = 3, nnz = 3) (3, 1) > 1 (2, 2) > 1 (1, 3) > 1 Cheers David  Octave is freely available under the terms of the GNU GPL. Octave's home on the web: http://www.octave.org How to fund new projects: http://www.octave.org/funding.html Subscription information: http://www.octave.org/archive.html 
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