I did it, but gmres with boomeramg diverges. The system has three unknowns per mesh node. Each block operator is either a Laplace or the mass matrix. So each block by-itself is solvable with amg. Thus it follows that the overall system is solvable? In my case the system is not symmetric and indefinite. The boundary conditions are Neuman everywhere, but the global matrix has an empty null space. As the local blocks (in the case of the discrete Laplace) have constant null space I set -pc_hypre_boomeramg_relax_type_coarse Jacobi for boomeramg not to make direct solves on coarse grid. Is there any theoretical reason that AMG cannot work in this case or is it a question of just the right settings for the solver?
Thomas Am 02.02.2012 14:43, schrieb Mark F. Adams: > Use MatSetBlockSize(mat,ndof); and that info will get passed down to HYPRE. > Mark > > On Feb 2, 2012, at 7:09 AM, Thomas Witkowski wrote: > >> The documentation of boomeramg mention that it's possible to solve also >> matrices arising from the discretization of system of PDEs. But there is no >> more information on it. What should I do to make use of it in PETSc? >> >> Thomas >>
