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
