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eigenvectors cannot find eigenvales of simple matrix #3042

Open rtoy opened 3 months ago

rtoy commented 3 months ago

Imported from SourceForge on 2024-07-07 09:37:07 Created by senger123 on 2018-10-08 13:24:34 Original: https://sourceforge.net/p/maxima/bugs/3472

This seems to be a bug:

rtoy commented 3 months ago

Imported from SourceForge on 2024-07-07 09:37:08 Created by robert_dodier on 2020-07-29 22:06:33 Original: https://sourceforge.net/p/maxima/bugs/3472/#25d6

rtoy commented 3 months ago

Imported from SourceForge on 2024-07-07 09:37:12 Created by robert_dodier on 2020-07-29 22:06:34 Original: https://sourceforge.net/p/maxima/bugs/3472/#19c0

Hmm, I can't reproduce that behavior. I am working w/ Maxima 5.44.0 + SBCL 2.0.5 + MacOS. I get what look like plausible results.

(%i2) y5: matrix([0,0,1,0], [0,0,0,1],[1, 0,0,0],[0,1,0,0]);
                         [ 0  0  1  0 ]
                         [            ]
                         [ 0  0  0  1 ]
(%o2)                    [            ]
                         [ 1  0  0  0 ]
                         [            ]
                         [ 0  1  0  0 ]
(%i3) eigenvalues(y5);
(%o3)                  [[- 1, 1], [2, 2]]
(%i4) eigenvectors(y5);
(%o4) [[[- 1, 1], [2, 2]], [[[1, 0, - 1, 0], [0, 1, 0, - 1]], 
                                   [[1, 0, 1, 0], [0, 1, 0, 1]]]]
rtoy commented 3 months ago

Imported from SourceForge on 2024-07-07 09:37:15 Created by robert_dodier on 2020-07-31 15:35:37 Original: https://sourceforge.net/p/maxima/bugs/3472/#6f87

Hmm, I tried to reproduce this bug with Maxima 5.42.2 and 5.43.2 and I don't see it. It occurs to me that maybe it is possible that the program E4.mac contains something which is interfering with eigenvectors and/or solve. Matias, can you post the file E4.mac ? I will try it with that specific file.

rtoy commented 3 months ago

Imported from SourceForge on 2024-07-07 09:37:19 Created by robert_dodier on 2020-07-31 15:38:10 Original: https://sourceforge.net/p/maxima/bugs/3472/#c8fd

I'm marking this item as "pending" which means that it will be closed automatically in a couple of weeks. I don't doubt that it is a real problem and in the absence of further information, it can't be solved. But at any time, even when it's closed, if E4.mac can be attached, then I will look at it again.