Talk:LU decomposition: Difference between revisions

There are other problems: the Fortran code did the permutation in a blatantly inefficient way (permute all the lower rows at each step), and the author didn't notice that if you permute the whole rows, you don't have to permute anything afterwards to get the L and U components in A: they are just the lower and upper part of A. It's a matrix trick that's easy to prove.