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Re: [Pkgoctavedevel] Bug#394982: octave2.9: Crashes on "x(:,
From: 
John W. Eaton 
Subject: 
Re: [Pkgoctavedevel] Bug#394982: octave2.9: Crashes on "x(:, 
Date: 
Wed, 25 Oct 2006 19:31:38 0400 
On 26Oct2006, David Bateman wrote:
 Ok then use the attached patch in addition to the previous patch... It
 essentially removes the previous patch and does it differently.

 Note that this is still a very bad idea as it reallocates the memory to
 the sparse matrix and every assignment, even if you size the initial
 matrix correctly. This is due to the fact that only enough space for the
 nonzeros is ever created... I'd therefore highly recommended forming
 vectors of row, col and value and use the sparse function instead. This
 is discussed in the sparse section of the manual....
I applied the patch and now I see
octave:5> x = sparse (2,0)
x = Compressed Column Sparse (rows = 2, cols = 0, nnz = 0)
octave:6> x(:,1:2) = speye (2)
x =
1 0
0 1
octave:7> x(:,3:4) = speye (2)
x =
1 0 1 0
0 1 0 1
so it seems OK, but what is happening here:
octave:1> x = sparse (2,0)
x = Compressed Column Sparse (rows = 2, cols = 0, nnz = 0)
octave:2> x(:,2,3) = speye (2)
error: A(I, J) = X: can only have 1 or 2 indexes for sparse matrices
error: assignment failed, or no method for `sparse matrix = sparse matrix'
error: evaluating assignment expression near line 2, column 10
octave:2> x
x = Compressed Column Sparse (rows = 2, cols = 0, nnz = 0)
octave:3> x(:,1:2) = speye (2)
error: A(I, J) = X: can only have 1 or 2 indexes for sparse matrices
error: assignment failed, or no method for `sparse matrix = sparse matrix'
error: evaluating assignment expression near line 3, column 10
The command on line 2 was a mistake, but it seems to have a persistent
effect. Even though x still seems to be a 2x0 sparse matrix,
subsequent assignments fail after the first failure. Clearing x
allows it to work again, but how is it that the error is causing the
later failures?
jwe
 Re: [Pkgoctavedevel] Bug#394982: octave2.9: Crashes on "x(:, :)=speye(1)", (continued)
 Re: [Pkgoctavedevel] Bug#394982: octave2.9: Crashes on "x(:, :)=speye(1)", Rafael Laboissiere, 2006/10/24
 Re: [Pkgoctavedevel] Bug#394982: octave2.9: Crashes on "x(:, :)=speye(1)", Quentin Spencer, 2006/10/24
 Re: [Pkgoctavedevel] Bug#394982: octave2.9: Crashes on "x(:, :)=speye(1)", John W. Eaton, 2006/10/24
 Re: [Pkgoctavedevel] Bug#394982: octave2.9: Crashes on "x(:, :)=speye(1)", David Bateman, 2006/10/24
 Re: [Pkgoctavedevel] Bug#394982: octave2.9: Crashes on "x(:,, David Bateman, 2006/10/24
 Re: [Pkgoctavedevel] Bug#394982: octave2.9: Crashes on "x(:,, Rafael Laboissiere, 2006/10/24
 Re: [Pkgoctavedevel] Bug#394982: octave2.9: Crashes on "x(:,, John W. Eaton, 2006/10/24
 Re: [Pkgoctavedevel] Bug#394982: octave2.9: Crashes on "x(:,, Kim Hansen, 2006/10/25
 Re: [Pkgoctavedevel] Bug#394982: octave2.9: Crashes on "x(:,, Rafael Laboissiere, 2006/10/25
 Re: [Pkgoctavedevel] Bug#394982: octave2.9: Crashes on "x(:,, David Bateman, 2006/10/25
 Re: [Pkgoctavedevel] Bug#394982: octave2.9: Crashes on "x(:,,
John W. Eaton <=
 Re: [Pkgoctavedevel] Bug#394982: octave2.9: Crashes on "x(:,, John W. Eaton, 2006/10/25
 Re: [Pkgoctavedevel] Bug#394982: octave2.9: Crashes on "x(:,, Kim Hansen, 2006/10/26
 Re: [Pkgoctavedevel] Bug#394982: octave2.9: Crashes on "x(:,, David Bateman, 2006/10/26
 Re: [Pkgoctavedevel] Bug#394982: octave2.9: Crashes on "x(:,, Kim Hansen, 2006/10/26