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Talk:LU decomposition: Difference between revisions
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I did not change the article because it seemed very strange that I would be the first to see this and I therefore wonder if I'm not wrong.
== Re: Example 2 pivot matrix seems to be wrong ==
I noticed this too. In the implementations it appears that the max pivot values are taken from the original A matrix without swapping. When the max pivot is being found for row 3 of A the choices presented are row 3 [3, 7, 18, 1] and row 4 [2, 5, 7, 1], since row 3 contains the largest pivot value the third row of the current permutation matrix is swapped with itself, which contains [0, 1, 0, 0] from the initial swap with row 2. It's strange, but a lot of the algorithm implementations seem to follow that trend and multiplying by the permutation matrix instead of swapping inline with the permutation matrix.
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