Hello, there is a FAQ and a Stackoverflow article about getting the condition number of a petsc matrix:
http://www.mcs.anl.gov/petsc/documentation/faq.html#conditionnumber http://scicomp.stackexchange.com/questions/34/how-can-i-estimate-the-condition-number-of-a-large-sparse-matrix-using-petsc Both tell me to add: -pc_type none -ksp_type gmres -ksp_monitor_singular_value -ksp_gmres_restart 1000 to my options. I add the line to .petscrc but nothing happens, no additional output at all. I added -ksp_view, so my .petscrc looks like that: -ksp_view -pc_type none -ksp_type gmres -ksp_monitor_singular_value -ksp_gmres_restart 1000 The complete output is below, but something I wonder about: GMRES: restart=30, shouldn't that be 1000 And where can I read out the condition number approximation? Thanks, Florian KSP Object: 1 MPI processes type: gmres GMRES: restart=30, using Classical (unmodified) Gram-Schmidt Orthogonalization with no iterative refinement GMRES: happy breakdown tolerance 1e-30 maximum iterations=10000 tolerances: relative=1e-09, absolute=1e-50, divergence=10000. left preconditioning using nonzero initial guess using PRECONDITIONED norm type for convergence test PC Object: 1 MPI processes type: none linear system matrix = precond matrix: Mat Object: C 1 MPI processes type: seqsbaij rows=14403, cols=14403 total: nonzeros=1044787, allocated nonzeros=1123449 total number of mallocs used during MatSetValues calls =72016 block size is 1 (0) 13:58:35 [precice::impl::SolverInterfaceImpl]:395 in initialize: it 1 of 1 | dt# 1 | t 0 of 1 | dt 1 | max dt 1 | ongoing yes | dt complete no | (0) 13:58:35 [precice::impl::SolverInterfaceImpl]:446 in advance: Iteration #1 KSP Object: 1 MPI processes type: gmres GMRES: restart=30, using Classical (unmodified) Gram-Schmidt Orthogonalization with no iterative refinement GMRES: happy breakdown tolerance 1e-30 maximum iterations=10000 tolerances: relative=1e-09, absolute=1e-50, divergence=10000. left preconditioning using nonzero initial guess using PRECONDITIONED norm type for convergence test PC Object: 1 MPI processes type: none linear system matrix = precond matrix: Mat Object: C 1 MPI processes type: seqsbaij rows=14403, cols=14403 total: nonzeros=1044787, allocated nonzeros=1123449 total number of mallocs used during MatSetValues calls =72016 block size is 1
