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Re: About diagonal matrices
From: |
John W. Eaton |
Subject: |
Re: About diagonal matrices |
Date: |
Sat, 21 Feb 2009 16:41:03 -0500 |
On 20-Feb-2009, dbateman wrote:
| I consider that the fact speye(3)/0 returns a full matrix a bug unless the
| sparse_auto_mutate function is set. In fact this behavior is a hang over
| from when sparse_auto_mutate(1) was not only the default but only behavior
| and certain narrowing could be donee in the operators themselves rather than
| the narrowing function of the octave_value. I pushed a patch..
|
|
|
| octave:4> a = eye(3)/0
| a =
|
| Inf 0 0
| 0 Inf 0
| 0 0 Inf
|
| octave:5> a = speye(3)/0
| warning: division by zero
| a =
|
| Compressed Column Sparse (rows = 3, cols = 3, nnz = 3 [33%])
| )
|
| (1, 1) -> Inf
| (2, 2) -> Inf
| (3, 3) -> Inf
|
| octave:14> full(a)/0
| warning: division by zero
| ans =
|
| Inf NaN NaN
| NaN Inf NaN
| NaN NaN Inf
|
| and would expect the NaN fill in even for diagonal matrices as John
| suggested and so the NaN values. The current Octave behavior is
| mathematically wrong and saying thats the answer the user expected is no
| excuse. We should bring back the NaN fill-in.
With the current sources, which I think includes your patch, I now see
octave:2> speye (3)/0
warning: division by zero
ans =
Compressed Column Sparse (rows = 3, cols = 3, nnz = 3 [33%])
)
(1, 1) -> Inf
(2, 2) -> Inf
(3, 3) -> Inf
octave:3> speye (3)*Inf
ans =
Compressed Column Sparse (rows = 3, cols = 3, nnz = 3 [33%])
)
(1, 1) -> Inf
(2, 2) -> Inf
(3, 3) -> Inf
octave:4> speye (3)*NaN
ans =
Compressed Column Sparse (rows = 3, cols = 3, nnz = 3 [33%])
)
(1, 1) -> NaN
(2, 2) -> NaN
(3, 3) -> NaN
Is that the behavior you want?
jwe
- Re: About diagonal matrices, (continued)
- Re: About diagonal matrices, dbateman, 2009/02/24
- Re: About diagonal matrices, dbateman, 2009/02/24
- Re: About diagonal matrices, Jaroslav Hajek, 2009/02/24
- Re: About diagonal matrices, Jaroslav Hajek, 2009/02/24
- Re: About diagonal matrices, Jaroslav Hajek, 2009/02/21
- Re: About diagonal matrices, Søren Hauberg, 2009/02/21
- Re: About diagonal matrices, Jaroslav Hajek, 2009/02/21
- Re: About diagonal matrices, John W. Eaton, 2009/02/21
- Re: About diagonal matrices,
John W. Eaton <=
- Re: About diagonal matrices, Jaroslav Hajek, 2009/02/22
- Re: About diagonal matrices, dbateman, 2009/02/25
- Re: About diagonal matrices, Jaroslav Hajek, 2009/02/25
- Re: About diagonal matrices, dbateman, 2009/02/25
- Re: About diagonal matrices, Jaroslav Hajek, 2009/02/26
- Re: About diagonal matrices, John W. Eaton, 2009/02/26
- Re: About diagonal matrices, Jaroslav Hajek, 2009/02/26
Re: About diagonal matrices, Daniel J Sebald, 2009/02/20
Re: About diagonal matrices, Daniel J Sebald, 2009/02/20