Talk:LU decomposition: Difference between revisions
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[http://www.wolframalpha.com/input/?i=lu+decomposition+{{1%2C+1%2C+1%2C+1}%2C+{1%2C+1%2C+-1%2C+-1}%2C+{1%2C+-1%2C+0%2C+0}%2C+{0%2C+0%2C+1%2C+-1}}] |
[http://www.wolframalpha.com/input/?i=lu+decomposition+{{1%2C+1%2C+1%2C+1}%2C+{1%2C+1%2C+-1%2C+-1}%2C+{1%2C+-1%2C+0%2C+0}%2C+{0%2C+0%2C+1%2C+-1}}] |
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The permutation matrix has to be updated at each step, but that will make the code a lot more complicated. |
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I guess the pivotization is at fault. |
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Revision as of 16:33, 18 November 2014
The Python example has a divide by zero error for the matrix
b = [[1, 1, 1, 1], [1, 1, -1, -1], [1, -1, 0, 0], [0, 0, 1, -1]]
although a LUP decomposition exists: [1]
The permutation matrix has to be updated at each step, but that will make the code a lot more complicated.