User mike - MathOverflow most recent 30 from http://mathoverflow.net 2013-06-20T04:40:58Z http://mathoverflow.net/feeds/user/22949 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/94198/sparsity-of-qr-decomposition sparsity of QR decomposition Mike 2012-04-16T10:40:40Z 2012-04-17T07:18:26Z <p>Hi, everyone!</p> <p>I have a sparse $n \times n$ matrix $A$ with $nnz(A)$ denoting the number of non-zero entries in $A$. Now I use QR factorization to decompose $A$ into an orthogonal matrix $Q$ and triangular matrix $R$. My problem is that : can we use some methods to control the sparsity of $Q$ satisfying $nnz(Q) \le nnz(A)$. </p> http://mathoverflow.net/questions/94198/sparsity-of-qr-decomposition Comment by Mike Mike 2012-04-17T11:26:54Z 2012-04-17T11:26:54Z What about the sparsity of $R$ wrt that of $A$ ?