Reference documentation for deal.II version Git 4e68a80cad 20211022 15:50:12 0600

#include <deal.II/lac/trilinos_precondition.h>
Classes  
struct  AdditionalData 
Public Types  
using  size_type = ::types::global_dof_index 
Public Member Functions  
~PreconditionAMG () override  
void  initialize (const SparseMatrix &matrix, const AdditionalData &additional_data=AdditionalData()) 
void  initialize (const Epetra_RowMatrix &matrix, const AdditionalData &additional_data=AdditionalData()) 
void  initialize (const SparseMatrix &matrix, const Teuchos::ParameterList &ml_parameters) 
void  initialize (const Epetra_RowMatrix &matrix, const Teuchos::ParameterList &ml_parameters) 
template<typename number >  
void  initialize (const ::SparseMatrix< number > &deal_ii_sparse_matrix, const AdditionalData &additional_data=AdditionalData(), const double drop_tolerance=1e13, const ::SparsityPattern *use_this_sparsity=nullptr) 
void  reinit () 
void  clear () 
size_type  memory_consumption () const 
MPI_Comm  get_mpi_communicator () const 
void  transpose () 
virtual void  vmult (MPI::Vector &dst, const MPI::Vector &src) const 
virtual void  vmult (::Vector< double > &dst, const ::Vector< double > &src) const 
virtual void  vmult (::LinearAlgebra::distributed::Vector< double > &dst, const ::LinearAlgebra::distributed::Vector< double > &src) const 
virtual void  Tvmult (MPI::Vector &dst, const MPI::Vector &src) const 
virtual void  Tvmult (::Vector< double > &dst, const ::Vector< double > &src) const 
virtual void  Tvmult (::LinearAlgebra::distributed::Vector< double > &dst, const ::LinearAlgebra::distributed::Vector< double > &src) const 
template<class Archive >  
void  serialize (Archive &ar, const unsigned int version) 
Access to underlying Trilinos data  
Epetra_Operator &  trilinos_operator () const 
Partitioners  
IndexSet  locally_owned_domain_indices () const 
IndexSet  locally_owned_range_indices () const 
Subscriptor functionality  
Classes derived from Subscriptor provide a facility to subscribe to this object. This is mostly used by the SmartPointer class.  
void  subscribe (std::atomic< bool > *const validity, const std::string &identifier="") const 
void  unsubscribe (std::atomic< bool > *const validity, const std::string &identifier="") const 
unsigned int  n_subscriptions () const 
template<typename StreamType >  
void  list_subscribers (StreamType &stream) const 
void  list_subscribers () const 
Static Public Member Functions  
static ::ExceptionBase &  ExcNonMatchingMaps (std::string arg1) 
static ::ExceptionBase &  ExcInUse (int arg1, std::string arg2, std::string arg3) 
static ::ExceptionBase &  ExcNoSubscriber (std::string arg1, std::string arg2) 
Protected Attributes  
Teuchos::RCP< Epetra_Operator >  preconditioner 
Epetra_MpiComm  communicator 
std::shared_ptr< Epetra_Map >  vector_distributor 
Private Attributes  
std::shared_ptr< SparseMatrix >  trilinos_matrix 
This class implements an algebraic multigrid (AMG) preconditioner based on the Trilinos ML implementation, which is a blackbox preconditioner that works well for many PDEbased linear problems. What this class does is twofold. When the initialize() function is invoked, a ML preconditioner object is created based on the matrix that we want the preconditioner to be based on. A call of the respective vmult
function does call the respective operation in the Trilinos package, where it is called ApplyInverse
. Use of this class is explained in the step31 tutorial program.
Since the Trilinos objects we want to use are heavily dependent on Epetra objects, we recommend using this class in conjunction with Trilinos (Epetra) sparse matrices and vectors. There is support for use with matrices of the SparseMatrix class and corresponding vectors, too, but this requires generating a copy of the matrix, which is slower and takes (much) more memory. When doing such a copy operation, we can still profit from the fact that some of the entries in the preconditioner matrix are zero and hence can be neglected.
The implementation is able to distinguish between matrices from elliptic problems and convection dominated problems. We use the standard options provided by Trilinos ML for elliptic problems, except that we use a Chebyshev smoother instead of a symmetric GaussSeidel smoother. For most elliptic problems, Chebyshev provides a better damping of high frequencies (in the algebraic sense) than GaussSeidel (SSOR), and is faster (Chebyshev requires only some matrixvector products, whereas SSOR requires substitutions which are more expensive). Moreover, Chebyshev is perfectly parallel in the sense that it does not degenerate when used on many processors. SSOR, on the other hand, gets more Jacobilike on many processors.
For proper functionality of this class we recommend using Trilinos v9.0 and higher. Older versions may have problems with generating the coarse matrix structure when using matrices with many nonzero entries per row (i.e., matrices stemming from higher order finite element discretizations).
Definition at line 1336 of file trilinos_precondition.h.

inherited 
Declare the type for container size.
Definition at line 82 of file trilinos_precondition.h.

override 
Destructor.
Definition at line 213 of file trilinos_precondition_ml.cc.
void TrilinosWrappers::PreconditionAMG::initialize  (  const SparseMatrix &  matrix, 
const AdditionalData &  additional_data = AdditionalData() 

) 
Let Trilinos compute a multilevel hierarchy for the solution of a linear system with the given matrix. The function uses the matrix format specified in TrilinosWrappers::SparseMatrix.
Definition at line 222 of file trilinos_precondition_ml.cc.
void TrilinosWrappers::PreconditionAMG::initialize  (  const Epetra_RowMatrix &  matrix, 
const AdditionalData &  additional_data = AdditionalData() 

) 
Let Trilinos compute a multilevel hierarchy for the solution of a linear system with the given matrix. As opposed to the other initialize function above, this function uses an abstract interface to an object of type Epetra_RowMatrix which allows a user to pass quite general objects to the ML preconditioner.
This initialization routine is useful in cases where the operator to be preconditioned is not a TrilinosWrappers::SparseMatrix object but still allows getting a copy of the entries in each of the locally owned matrix rows (method ExtractMyRowCopy) and implements a matrixvector product (methods Multiply or Apply). An example are operators which provide faster matrixvector multiplications than possible with matrix entries (matrixfree methods). These implementations can be beneficially combined with Chebyshev smoothers that only perform matrixvector products. The interface class Epetra_RowMatrix is very flexible to enable this kind of implementation.
Definition at line 231 of file trilinos_precondition_ml.cc.
void TrilinosWrappers::PreconditionAMG::initialize  (  const SparseMatrix &  matrix, 
const Teuchos::ParameterList &  ml_parameters  
) 
Let Trilinos compute a multilevel hierarchy for the solution of a linear system with the given matrix. The function uses the matrix format specified in TrilinosWrappers::SparseMatrix.
This function is similar to the one above, but allows the user to set all the options of the Trilinos ML preconditioner. In order to find out about all the options for ML, we refer to the ML documentation page. In particular, users need to follow the ML instructions in case a vectorvalued problem ought to be solved.
Definition at line 257 of file trilinos_precondition_ml.cc.
void TrilinosWrappers::PreconditionAMG::initialize  (  const Epetra_RowMatrix &  matrix, 
const Teuchos::ParameterList &  ml_parameters  
) 
Let Trilinos compute a multilevel hierarchy for the solution of a linear system with the given matrix. As opposed to the other initialize function above, this function uses an abstract interface to an object of type Epetra_RowMatrix which allows a user to pass quite general objects to the ML preconditioner.
Definition at line 266 of file trilinos_precondition_ml.cc.
void TrilinosWrappers::PreconditionAMG::initialize  (  const ::SparseMatrix< number > &  deal_ii_sparse_matrix, 
const AdditionalData &  additional_data = AdditionalData() , 

const double  drop_tolerance = 1e13 , 

const ::SparsityPattern *  use_this_sparsity = nullptr 

) 
Let Trilinos compute a multilevel hierarchy for the solution of a linear system with the given matrix. This function takes a deal.II matrix and copies the content into a Trilinos matrix, so the function can be considered rather inefficient.
Definition at line 277 of file trilinos_precondition_ml.cc.
void TrilinosWrappers::PreconditionAMG::reinit  (  ) 
This function can be used for a faster recalculation of the preconditioner construction when the matrix entries underlying the preconditioner have changed, but the matrix sparsity pattern has remained the same. What this function does is taking the already generated coarsening structure, computing the AMG prolongation and restriction according to a smoothed aggregation strategy and then building the whole multilevel hierarchy. This function can be considerably faster than the initialize function, since the coarsening pattern is usually the most difficult thing to do when setting up the AMG ML preconditioner.
Definition at line 311 of file trilinos_precondition_ml.cc.
void TrilinosWrappers::PreconditionAMG::clear  (  ) 
Destroys the preconditioner, leaving an object like just after having called the constructor.
Definition at line 321 of file trilinos_precondition_ml.cc.
PreconditionAMG::size_type TrilinosWrappers::PreconditionAMG::memory_consumption  (  )  const 
Prints an estimate of the memory consumption of this class.
Definition at line 330 of file trilinos_precondition_ml.cc.

inherited 
Return the MPI communicator object in use with this matrix.
Definition at line 59 of file trilinos_precondition.cc.

inherited 
Sets an internal flag so that all operations performed by the matrix, i.e., multiplications, are done in transposed order. However, this does not reshape the matrix to transposed form directly, so care should be taken when using this flag.

virtualinherited 
Apply the preconditioner.
Reimplemented in TrilinosWrappers::PreconditionIdentity.

virtualinherited 
Apply the preconditioner on deal.II data structures instead of the ones provided in the Trilinos wrapper class.
Reimplemented in TrilinosWrappers::PreconditionIdentity.

virtualinherited 
Apply the preconditioner on deal.II parallel data structures instead of the ones provided in the Trilinos wrapper class.

virtualinherited 
Apply the transpose preconditioner.
Reimplemented in TrilinosWrappers::PreconditionIdentity.

virtualinherited 
Apply the transpose preconditioner on deal.II data structures instead of the ones provided in the Trilinos wrapper class.
Reimplemented in TrilinosWrappers::PreconditionIdentity.

virtualinherited 
Apply the transpose preconditioner on deal.II parallel data structures instead of the ones provided in the Trilinos wrapper class.

inherited 
Calling this function from an uninitialized object will cause an exception.
Definition at line 66 of file trilinos_precondition.cc.

inherited 
Return the partitioning of the domain space of this matrix, i.e., the partitioning of the vectors this matrix has to be multiplied with.
Definition at line 75 of file trilinos_precondition.cc.

inherited 
Return the partitioning of the range space of this matrix, i.e., the partitioning of the vectors that are result from matrixvector products.
Definition at line 82 of file trilinos_precondition.cc.

inherited 
Subscribes a user of the object by storing the pointer validity
. The subscriber may be identified by text supplied as identifier
.
Definition at line 136 of file subscriptor.cc.

inherited 
Unsubscribes a user from the object.
identifier
and the validity
pointer must be the same as the one supplied to subscribe(). Definition at line 156 of file subscriptor.cc.

inlineinherited 
Return the present number of subscriptions to this object. This allows to use this class for reference counted lifetime determination where the last one to unsubscribe also deletes the object.
Definition at line 301 of file subscriptor.h.

inlineinherited 
List the subscribers to the input stream
.
Definition at line 318 of file subscriptor.h.

inherited 
List the subscribers to deallog
.
Definition at line 204 of file subscriptor.cc.

inlineinherited 
Read or write the data of this object to or from a stream for the purpose of serialization using the BOOST serialization library.
This function does not actually serialize any of the member variables of this class. The reason is that what this class stores is only who subscribes to this object, but who does so at the time of storing the contents of this object does not necessarily have anything to do with who subscribes to the object when it is restored. Consequently, we do not want to overwrite the subscribers at the time of restoring, and then there is no reason to write the subscribers out in the first place.
Definition at line 310 of file subscriptor.h.

private 
A copy of the deal.II matrix into Trilinos format.
Definition at line 1689 of file trilinos_precondition.h.

protectedinherited 
This is a pointer to the preconditioner object that is used when applying the preconditioner.
Definition at line 232 of file trilinos_precondition.h.

protectedinherited 
Internal communication pattern in case the matrix needs to be copied from deal.II format.
Definition at line 238 of file trilinos_precondition.h.

protectedinherited 
Internal Trilinos map in case the matrix needs to be copied from deal.II format.
Definition at line 244 of file trilinos_precondition.h.