# Working on eigs

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## Working on eigs

 Dear maintainers, I started to work on eigs. I closed bugs #39573 and #50546 (changesets already in stable). I have also a patch for #45153 and #47236 which you can find on my Bitbucket repository https://bitbucket.org/caliari/octave/(eigs bookmark). I introduced the [L,U,P,Q,R] = lu (A) factorization for the sparse case and [L,U,P] = lu(A) for the full case. I used this test clear all n = 50; A = toeplitz ((n + 1) ^ 2 * [2, -1, zeros(1, n - 2)]); %A = toeplitz (sparse ((n + 1) ^ 2 * [2, -1, zeros(1, n - 2)])); A = kron (A, eye (n)) + kron (eye (n), A); opts.v0 = (1:length (A))'; opts.disp = 2; tic eigs (A, 10, 'sm', opts) % new: 4.2 seconds % old: 6.4 seconds toc b = ones (length(A), 1); tic [L, U, P] = lu (A); toc tic U \ (L \ (P * b)); toc to show the effectiveness of [L,U,P] factorization. Matlab in this case is much faster, but I think it depends on the underlying optimized linear algebra (MKL), since the factorization itself and the solution of triangular systems is faster in Matlab. I was working on #49523 but do not know how to continue. Another thing surely missing is the 'single' version of eigs. I think the main problems are fixed now, but please review my patches and feel free to contact me for additional issues with eigs. Marco