Thank you for the inputs. I tried Barry' s suggestion to use SuperLU, but the solution does not converge and on doing -ksp_monitor -ksp_converged_reason. I get the following error:- 240 KSP Residual norm 1.722571678777e+07 Linear solve did not converge due to DIVERGED_DTOL iterations 240 For some reason it is diverging, although I am sure that for the given system a unique solution exists.
Thanks, Kaushik On Tue, Apr 11, 2017 at 1:04 AM, Xiaoye S. Li <[email protected]> wrote: > If you need to use SuperLU_DIST, the pivoting is done statically, using > maximum weighted matching, so the small diagonals are usually taken care as > well. It is not as good as partial pivoting, but works most of the time. > > Sherry > > On Mon, Apr 10, 2017 at 12:07 PM, Barry Smith <[email protected]> wrote: > >> >> I would suggest using ./configure --download-superlu and then when >> running the program -pc_type lu -pc_factor_mat_solver_package superlu >> >> Note that this is SuperLU, it is not SuperLU_DIST. Superlu uses >> partial pivoting for numerical stability so should be able to handle the >> small or zero diagonal entries. >> >> Barry >> >> > On Apr 10, 2017, at 1:17 PM, Kaushik Kulkarni <[email protected]> >> wrote: >> > >> > Hello, >> > I am trying to solve a 2500x2500 sparse matrix. To get an idea about >> the matrix structure I have added a file matrix.log which contains the >> output of MatView() and also the output of Matview_draw in the image file. >> > >> > From the matrix structure it can be seen that Jacobi iteration won't >> work and some of the diagonal entries being very low(of the order of 1E-16) >> LU factorization would also fail. >> > >> > Can someone please suggest what all could I try next, in order to make >> the solution converge? >> > >> > Thanks, >> > Kaushik >> > >> > -- >> > Kaushik Kulkarni >> > Fourth Year Undergraduate >> > Department of Mechanical Engineering >> > Indian Institute of Technology Bombay >> > Mumbai, India >> > https://kaushikcfd.github.io/About/ >> > +91-9967687150 >> > <matrix.log><matrix_pattern.png> >> >> > -- Kaushik Kulkarni Fourth Year Undergraduate Department of Mechanical Engineering Indian Institute of Technology Bombay Mumbai, India https://kaushikcfd.github.io/About/ +91-9967687150
