Try adding -pc_factor_shift_type nonzero > On Mar 31, 2016, at 8:43 PM, Harriet Li <kame...@gmail.com> wrote: > > Hello, > > I'm trying to solve the KKT system for an inverse problem with > convection-diffusion physics. Using the input > > -ksp_monitor_singular_value -ksp_gmres_modifiedgramschmidt > -ksp_gmres_restart 500 -pc_type ilu -pc_factor_levels > > I get > > Solving time step 0, time = 0 > Assembling the System > Nonlinear Residual: 0.485446 > Linear solve starting, tolerance 0.000485446 > 0 KSP Residual norm -nan % max 1.000000000000e+00 min > 1.000000000000e+00 max/min 1.000000000000e+00 > Linear solve finished, step 0, residual -nan > Trying full Newton step > Current Residual: 0.485446 > Shrinking Newton step to 0.618034 > Current Residual: 0.485446 > ... > > However, if I use superlu, > > -ksp_type preonly -pc_type lu -pc_factor_mat_solver_package superlu > > then the system is solved without problems (end residual of O(e-17)). If I > print out the Jacobian and check it in Matlab, I see that it has full rank > and condition number of O(e3). > > Any thoughts on what's going on? I have libmesh 0.9.5 and petsc 1.3.6.1 > > Thanks, > Harriet > ------------------------------------------------------------------------------ > Transform Data into Opportunity. > Accelerate data analysis in your applications with > Intel Data Analytics Acceleration Library. > Click to learn more. > http://pubads.g.doubleclick.net/gampad/clk?id=278785471&iu=/4140 > _______________________________________________ > Libmesh-users mailing list > Libmesh-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/libmesh-users
------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785471&iu=/4140 _______________________________________________ Libmesh-users mailing list Libmesh-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-users
