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Reference documentation for deal.II version 9.6.2
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#include <deal.II/lac/trilinos_precondition.h>
Public Member Functions | |
AdditionalData (const bool elliptic=true, const bool higher_order_elements=false, const unsigned int n_cycles=1, const bool w_cycle=false, const double aggregation_threshold=1e-4, const std::vector< std::vector< bool > > &constant_modes=std::vector< std::vector< bool > >(0), const unsigned int smoother_sweeps=2, const unsigned int smoother_overlap=0, const bool output_details=false, const char *smoother_type="Chebyshev", const char *coarse_type="Amesos-KLU") | |
void | set_parameters (Teuchos::ParameterList ¶meter_list, std::unique_ptr< Epetra_MultiVector > &distributed_constant_modes, const Epetra_RowMatrix &matrix) const |
void | set_parameters (Teuchos::ParameterList ¶meter_list, std::unique_ptr< Epetra_MultiVector > &distributed_constant_modes, const SparseMatrix &matrix) const |
void | set_operator_null_space (Teuchos::ParameterList ¶meter_list, std::unique_ptr< Epetra_MultiVector > &distributed_constant_modes, const Epetra_RowMatrix &matrix) const |
void | set_operator_null_space (Teuchos::ParameterList ¶meter_list, std::unique_ptr< Epetra_MultiVector > &distributed_constant_modes, const SparseMatrix &matrix) const |
Public Attributes | |
bool | elliptic |
bool | higher_order_elements |
unsigned int | n_cycles |
bool | w_cycle |
double | aggregation_threshold |
std::vector< std::vector< bool > > | constant_modes |
unsigned int | smoother_sweeps |
unsigned int | smoother_overlap |
bool | output_details |
const char * | smoother_type |
const char * | coarse_type |
A data structure that is used to control details of how the algebraic multigrid is set up. The flags detailed in here are then passed to the Trilinos ML implementation. A structure of the current type are passed to the constructor of PreconditionAMG.
Definition at line 1329 of file trilinos_precondition.h.
TrilinosWrappers::PreconditionAMG::AdditionalData::AdditionalData | ( | const bool | elliptic = true, |
const bool | higher_order_elements = false, | ||
const unsigned int | n_cycles = 1, | ||
const bool | w_cycle = false, | ||
const double | aggregation_threshold = 1e-4, | ||
const std::vector< std::vector< bool > > & | constant_modes = std::vector<std::vector<bool>>(0), | ||
const unsigned int | smoother_sweeps = 2, | ||
const unsigned int | smoother_overlap = 0, | ||
const bool | output_details = false, | ||
const char * | smoother_type = "Chebyshev", | ||
const char * | coarse_type = "Amesos-KLU" ) |
Constructor. By default, we pretend to work on elliptic problems with linear finite elements on a scalar equation.
Making use of the DoFTools::extract_constant_modes() function, the constant_modes
vector can be initialized for a given field in the following manner:
Definition at line 38 of file trilinos_precondition_ml.cc.
void TrilinosWrappers::PreconditionAMG::AdditionalData::set_parameters | ( | Teuchos::ParameterList & | parameter_list, |
std::unique_ptr< Epetra_MultiVector > & | distributed_constant_modes, | ||
const Epetra_RowMatrix & | matrix ) const |
Fill in a parameter_list
that can be used to initialize the AMG preconditioner.
The matrix
is used in conjunction with the constant_modes
to configure the null space settings for the preconditioner. The distributed_constant_modes
are initialized by this function, and must remain in scope until PreconditionAMG::initialize() has been called.
See the documentation for the Trilinos ML package for details on what options are available for modification.
Definition at line 66 of file trilinos_precondition_ml.cc.
void TrilinosWrappers::PreconditionAMG::AdditionalData::set_parameters | ( | Teuchos::ParameterList & | parameter_list, |
std::unique_ptr< Epetra_MultiVector > & | distributed_constant_modes, | ||
const SparseMatrix & | matrix ) const |
Fill in a parameter list that can be used to initialize the AMG preconditioner.
Definition at line 187 of file trilinos_precondition_ml.cc.
void TrilinosWrappers::PreconditionAMG::AdditionalData::set_operator_null_space | ( | Teuchos::ParameterList & | parameter_list, |
std::unique_ptr< Epetra_MultiVector > & | distributed_constant_modes, | ||
const Epetra_RowMatrix & | matrix ) const |
Configure the null space setting in the parameter_list
for the input matrix
based on the state of the constant_modes
variable.
Definition at line 126 of file trilinos_precondition_ml.cc.
void TrilinosWrappers::PreconditionAMG::AdditionalData::set_operator_null_space | ( | Teuchos::ParameterList & | parameter_list, |
std::unique_ptr< Epetra_MultiVector > & | distributed_constant_modes, | ||
const SparseMatrix & | matrix ) const |
Configure the null space setting in the parameter_list
for the input matrix
based on the state of the constant_modes
variable.
Definition at line 200 of file trilinos_precondition_ml.cc.
bool TrilinosWrappers::PreconditionAMG::AdditionalData::elliptic |
Determines whether the AMG preconditioner should be optimized for elliptic problems (ML option smoothed aggregation SA, using a Chebyshev smoother) or for non-elliptic problems (ML option non-symmetric smoothed aggregation NSSA, smoother is SSOR with underrelaxation).
Definition at line 1445 of file trilinos_precondition.h.
bool TrilinosWrappers::PreconditionAMG::AdditionalData::higher_order_elements |
Determines whether the matrix that the preconditioner is built upon is generated from linear or higher-order elements.
Definition at line 1451 of file trilinos_precondition.h.
unsigned int TrilinosWrappers::PreconditionAMG::AdditionalData::n_cycles |
Defines how many multigrid cycles should be performed by the preconditioner.
Definition at line 1457 of file trilinos_precondition.h.
bool TrilinosWrappers::PreconditionAMG::AdditionalData::w_cycle |
Defines whether a w-cycle should be used instead of the standard setting of a v-cycle.
Definition at line 1463 of file trilinos_precondition.h.
double TrilinosWrappers::PreconditionAMG::AdditionalData::aggregation_threshold |
This threshold tells the AMG setup how the coarsening should be performed. In the AMG used by ML, all points that strongly couple with the tentative coarse-level point form one aggregate. The term strong coupling is controlled by the variable aggregation_threshold, meaning that all elements that are not smaller than aggregation_threshold times the diagonal element do couple strongly.
Definition at line 1474 of file trilinos_precondition.h.
std::vector<std::vector<bool> > TrilinosWrappers::PreconditionAMG::AdditionalData::constant_modes |
Specifies the constant modes (near null space) of the matrix. This parameter tells AMG whether we work on a scalar equation (where the near null space only consists of ones, and default value is OK) or on a vector-valued equation. For vector-valued problem with n_components components, the provided constant_modes
should fulfill the following requirements:
We obtain the constant_modes fulfilling the above requirements with the function DoFTools::extract_constant_modes.
Definition at line 1500 of file trilinos_precondition.h.
unsigned int TrilinosWrappers::PreconditionAMG::AdditionalData::smoother_sweeps |
Determines how many sweeps of the smoother should be performed. When the flag elliptic is set to true, i.e., for elliptic or almost elliptic problems, the polynomial degree of the Chebyshev smoother is set to smoother_sweeps. The term sweeps refers to the number of matrix-vector products performed in the Chebyshev case. In the non-elliptic case, smoother_sweeps sets the number of SSOR relaxation sweeps for post-smoothing to be performed.
Definition at line 1512 of file trilinos_precondition.h.
unsigned int TrilinosWrappers::PreconditionAMG::AdditionalData::smoother_overlap |
Determines the overlap in the SSOR/Chebyshev error smoother when run in parallel.
Definition at line 1518 of file trilinos_precondition.h.
bool TrilinosWrappers::PreconditionAMG::AdditionalData::output_details |
If this flag is set to true, then internal information from the ML preconditioner is printed to screen. This can be useful when debugging the preconditioner.
Definition at line 1525 of file trilinos_precondition.h.
const char* TrilinosWrappers::PreconditionAMG::AdditionalData::smoother_type |
Determines which smoother to use for the AMG cycle. Possibilities for smoother_type are the following:
Definition at line 1561 of file trilinos_precondition.h.
const char* TrilinosWrappers::PreconditionAMG::AdditionalData::coarse_type |
Determines which solver to use on the coarsest level. The same settings as for the smoother type are possible.
Definition at line 1567 of file trilinos_precondition.h.