Public Member Functions | Public Attributes

PETScWrappers::PreconditionBoomerAMG::AdditionalData Struct Reference

List of all members.

Public Member Functions

 AdditionalData (const bool symmetric_operator=false, const double strong_threshold=0.25, const double max_row_sum=0.9, const unsigned int aggressive_coarsening_num_levels=0, const bool output_details=false)

Public Attributes

bool symmetric_operator
double strong_threshold
double max_row_sum
unsigned int aggressive_coarsening_num_levels
bool output_details

Detailed Description

Standardized data struct to pipe additional flags to the preconditioner.

Definition at line 729 of file petsc_precondition.h.


Constructor & Destructor Documentation

PETScWrappers::PreconditionBoomerAMG::AdditionalData::AdditionalData ( const bool  symmetric_operator = false,
const double  strong_threshold = 0.25,
const double  max_row_sum = 0.9,
const unsigned int  aggressive_coarsening_num_levels = 0,
const bool  output_details = false 
)

Constructor. Note that BoomerAMG offers a lot more options to set than what is exposed here.


Member Data Documentation

Set this flag to true if you have a symmetric system matrix and you want to use a solver which asumes a symmetric preconditioner like CG. The relaxation is done with SSOR/Jacobi when set to true and with SOR/Jacobi otherwise.

Definition at line 754 of file petsc_precondition.h.

Threshold of when nodes are considered strongly connected. See HYPRE_BoomerAMGSetStrongThreshold(). Recommended values are 0.25 for 2d and 0.5 for 3d problems, but it is problem dependent.

Definition at line 765 of file petsc_precondition.h.

If set to a value smaller than 1.0 then diagonally dominant parts of the matrix are treated as having no strongly connected nodes. If the row sum weighted by the diagonal entry is bigger than the given value, it is considered diagonally dominant. This feature is turned of by setting the value to 1.0. This is the default as some matrices can result in having only diagonally dominant entries and thus no multigrid levels are constructed. The default in BoomerAMG for this is 0.9. When you try this, check for a reasonable number of levels created.

Definition at line 788 of file petsc_precondition.h.

Number of levels of aggressive coarsening. Increasing this value reduces the construction time and memory requirements but may decrease effectiveness.

Definition at line 796 of file petsc_precondition.h.

Setting this flag to true produces debug output from HYPRE, when the preconditioner is constructed.

Definition at line 804 of file petsc_precondition.h.


The documentation for this struct was generated from the following file:
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deal.II documentation generated on Wed May 23 2012 12:04:19 by doxygen 1.7.3