Hello! I am solving a coupled multiphysics problem which has several different units, which leads to a poorly conditioned jacobian. I am using the following ksp options:
-ksp_type preonly -pc_type lu -pc_factor_mat_solver_package umfpack The results I am getting are not right and I suspect that the conditioning of the jacobian may be playing a part in that. I would like to improve the conditioning by using -ksp_diagonal_scale, but adding it does not seem to help. The documentation for this option says 'this routine is only used if the matrix and preconditioner matrix are the same thing'. Does that mean the command can only be used with no preconditioner? http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/KSP/KSPSetDiagonalScale.html All the best, -- Colin McAuliffe PhD Candidate Columbia University Department of Civil Engineering and Engineering Mechanics
