## [Vxl-users] some first results on Ax=b sparse system

 [Vxl-users] some first results on Ax=b sparse system From: - 2002-03-30 12:15:39 ```Hi, ... and the winner for now is: -> vnl_lsqr it solves my (non_only_diagonal, non_symmetric) test sparse system *incredibly* faster than vnl_svd with identical results, even for different tries with low zero_out_tol (whatever it is). matlab gets unacceptably slow above 5,000 x 5,000 - I dont have patience to wait, so no benchmark (ctrl^c) for matlab, vnl_lsqr solves it within a minute, but with the following remark: vnl_lsqr.cxx : The equations A*x = b are probably compatible. Norm(A*x - b) is as small as seems reasonable on this machine. which can be a key to very fast results (because my test system is too naive). This all was only *test* for not-comming-from-real-life Ax=b problem. I will be using it to solve real network problems within a few next weeks - I will let you know how results from lsqr, svd and matlab compare. thank you for all suggestions and help, Dominique ```

 [Vxl-users] some first results on Ax=b sparse system From: - 2002-03-30 12:15:39 ```Hi, ... and the winner for now is: -> vnl_lsqr it solves my (non_only_diagonal, non_symmetric) test sparse system *incredibly* faster than vnl_svd with identical results, even for different tries with low zero_out_tol (whatever it is). matlab gets unacceptably slow above 5,000 x 5,000 - I dont have patience to wait, so no benchmark (ctrl^c) for matlab, vnl_lsqr solves it within a minute, but with the following remark: vnl_lsqr.cxx : The equations A*x = b are probably compatible. Norm(A*x - b) is as small as seems reasonable on this machine. which can be a key to very fast results (because my test system is too naive). This all was only *test* for not-comming-from-real-life Ax=b problem. I will be using it to solve real network problems within a few next weeks - I will let you know how results from lsqr, svd and matlab compare. thank you for all suggestions and help, Dominique ```