The MLI Package¶
MLI is an object-oriented module that implements the class of algebraic multigrid algorithms based on Vanek and Brezina’s smoothed aggregation method [VaMB1996], [VaBM2001]. There are two main algorithms in this module - the original smoothed aggregation algorithm and the modified version that uses the finite element substructure matrices to construct the prolongation operators. As such, the later algorithm can only be used in the finite element context via the finite element interface. In addition, the nodal coordinates obtained via the finite element interface can be used to construct a better prolongation operator than the pure translation modes.
Below is an example on how to set up MLI as a preconditioner for conjugate gradient.
HYPRE_LSI_MLICreate(MPI_COMM_WORLD, &pcg_precond); HYPRE_LSI_MLISetParams(pcg_precond, "MLI strengthThreshold 0.08"); ... HYPRE_PCGSetPrecond(pcg_solver, (HYPRE_PtrToSolverFcn) HYPRE_LSI_MLISolve, (HYPRE_PtrToSolverFcn) HYPRE_LSI_MLISetup, pcg_precond);
Note that parameters are set via
HYPRE_LSI_MLISetParams. A list of valid
parameters that can be set using this routine can be found in the FEI section of
the reference manual.