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Subsection 9.2.4: CG Up Section 9.2: Configuring Linear Solvers Subsection 9.2.6: Schur

### 9.2.5 BoomerAMG

This solver, from the HYPRE library, is an adaptive multigrid solver. It often works better as a preconditioner to an iterative solver than as a stand-alone solver.
 parameter description default max_iter The maximum number of iterations 20 tol relative residual tolerance 1e-7 print_level The amount of information printed (0,1, or 2) 0 max_levels The max number of multigrid levels 25 coarsen_type Method of grid coarsening (library default) use_num_funcs Use dimensionality of solution variable in coarsening 0 (false) relax_type relaxation type 3 interp_type interpolation type 6 strong_threshold strong threshold 0.5 p_max_elmts P max elements 4 num_sweeps Number of sweeps 1 agg_num_levels Aggressive number of levels 0 nodal Nodal option 0 (false) do_jacobi Do jacobi preconditioning 0 (false) fail_max_iters Fail on max iterations (1) 1 (true)