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Belos::BlockGmresIter< ScalarType, MV, OP > Class Template Reference

This class implements the block GMRES iteration, where a block Krylov subspace is constructed. The QR decomposition of block, upper Hessenberg matrix is performed each iteration to update the least squares system and give the current linear system residuals. More...

#include <BelosBlockGmresIter.hpp>

Inheritance diagram for Belos::BlockGmresIter< ScalarType, MV, OP >:
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List of all members.

Public Types

typedef MultiVecTraits
< ScalarType, MV > 
MVT
typedef OperatorTraits
< ScalarType, MV, OP > 
OPT
typedef Teuchos::ScalarTraits
< ScalarType > 
SCT
typedef SCT::magnitudeType MagnitudeType

Public Member Functions

Constructors/Destructor
 BlockGmresIter (const Teuchos::RCP< LinearProblem< ScalarType, MV, OP > > &problem, const Teuchos::RCP< OutputManager< ScalarType > > &printer, const Teuchos::RCP< StatusTest< ScalarType, MV, OP > > &tester, const Teuchos::RCP< MatOrthoManager< ScalarType, MV, OP > > &ortho, Teuchos::ParameterList &params)
 BlockGmresIter constructor with linear problem, solver utilities, and parameter list of solver options.
virtual ~BlockGmresIter ()
 Destructor.
Solver methods
void iterate ()
 This method performs block Gmres iterations until the status test indicates the need to stop or an error occurs (in which case, an std::exception is thrown).
void initializeGmres (GmresIterationState< ScalarType, MV > newstate)
 Initialize the solver to an iterate, providing a complete state.
void initialize ()
 Initialize the solver with the initial vectors from the linear problem or random data.
GmresIterationState
< ScalarType, MV > 
getState () const
 Get the current state of the linear solver.
Status methods
int getNumIters () const
 Get the current iteration count.
void resetNumIters (int iter=0)
 Reset the iteration count.
Teuchos::RCP< const MV > getNativeResiduals (std::vector< MagnitudeType > *norms) const
 Get the norms of the residuals native to the solver.
Teuchos::RCP< MV > getCurrentUpdate () const
 Get the current update to the linear system.
void updateLSQR (int dim=-1)
 Method for updating QR factorization of upper Hessenberg matrix.
int getCurSubspaceDim () const
 Get the dimension of the search subspace used to generate the current solution to the linear problem.
int getMaxSubspaceDim () const
 Get the maximum dimension allocated for the search subspace.
Accessor methods
const LinearProblem
< ScalarType, MV, OP > & 
getProblem () const
 Get a constant reference to the linear problem.
int getBlockSize () const
 Get the blocksize to be used by the iterative solver in solving this linear problem.
void setBlockSize (int blockSize)
 Set the blocksize.
int getNumBlocks () const
 Get the maximum number of blocks used by the iterative solver in solving this linear problem.
void setNumBlocks (int numBlocks)
 Set the maximum number of blocks used by the iterative solver.
void setSize (int blockSize, int numBlocks)
 Set the blocksize and number of blocks to be used by the iterative solver in solving this linear problem.
bool isInitialized ()
 States whether the solver has been initialized or not.

Detailed Description

template<class ScalarType, class MV, class OP>
class Belos::BlockGmresIter< ScalarType, MV, OP >

This class implements the block GMRES iteration, where a block Krylov subspace is constructed. The QR decomposition of block, upper Hessenberg matrix is performed each iteration to update the least squares system and give the current linear system residuals.

Author:
Teri Barth and Heidi Thornquist

Definition at line 83 of file BelosBlockGmresIter.hpp.


Member Typedef Documentation

template<class ScalarType , class MV , class OP >
typedef MultiVecTraits<ScalarType,MV> Belos::BlockGmresIter< ScalarType, MV, OP >::MVT

Definition at line 90 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
typedef OperatorTraits<ScalarType,MV,OP> Belos::BlockGmresIter< ScalarType, MV, OP >::OPT

Definition at line 91 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
typedef Teuchos::ScalarTraits<ScalarType> Belos::BlockGmresIter< ScalarType, MV, OP >::SCT

Definition at line 92 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
typedef SCT::magnitudeType Belos::BlockGmresIter< ScalarType, MV, OP >::MagnitudeType

Definition at line 93 of file BelosBlockGmresIter.hpp.


Constructor & Destructor Documentation

template<class ScalarType , class MV , class OP >
Belos::BlockGmresIter< ScalarType, MV, OP >::BlockGmresIter ( const Teuchos::RCP< LinearProblem< ScalarType, MV, OP > > &  problem,
const Teuchos::RCP< OutputManager< ScalarType > > &  printer,
const Teuchos::RCP< StatusTest< ScalarType, MV, OP > > &  tester,
const Teuchos::RCP< MatOrthoManager< ScalarType, MV, OP > > &  ortho,
Teuchos::ParameterList params 
)

BlockGmresIter constructor with linear problem, solver utilities, and parameter list of solver options.

This constructor takes pointers required by the linear solver, in addition to a parameter list of options for the linear solver. These options include the following:

  • "Block Size" - an int specifying the block size used by the algorithm. This can also be specified using the setBlockSize() method. Default: 1
  • "Num Blocks" - an int specifying the maximum number of blocks allocated for the solver basis. Default: 25
  • "Restart Timers" = a bool specifying whether the timers should be restarted each time iterate() is called. Default: false
  • "Keep Hessenberg" = a bool specifying whether the upper Hessenberg should be stored separately from the least squares system. Default: false

Definition at line 340 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
virtual Belos::BlockGmresIter< ScalarType, MV, OP >::~BlockGmresIter ( ) [inline, virtual]

Destructor.

Definition at line 114 of file BelosBlockGmresIter.hpp.


Member Function Documentation

template<class ScalarType , class MV , class OP >
void Belos::BlockGmresIter< ScalarType, MV, OP >::iterate ( ) [virtual]

This method performs block Gmres iterations until the status test indicates the need to stop or an error occurs (in which case, an std::exception is thrown).

iterate() will first determine whether the solver is inintialized; if not, it will call initialize() using default arguments. After initialization, the solver performs block Gmres iterations until the status test evaluates as Passed, at which point the method returns to the caller.

The block Gmres iteration proceeds as follows:

  1. The operator problem->applyOp() is applied to the newest blockSize vectors in the Krylov basis.
  2. The resulting vectors are orthogonalized against the previous basis vectors, and made orthonormal.
  3. The Hessenberg matrix is updated.
  4. The least squares system is updated.

The status test is queried at the beginning of the iteration.

Possible exceptions thrown include the GmresIterationOrthoFailure.

Implements Belos::Iteration< ScalarType, MV, OP >.

Definition at line 657 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
void Belos::BlockGmresIter< ScalarType, MV, OP >::initializeGmres ( GmresIterationState< ScalarType, MV >  newstate) [virtual]

Initialize the solver to an iterate, providing a complete state.

The BlockGmresIter contains a certain amount of state, consisting of the current Krylov basis and the associated Hessenberg matrix.

initialize() gives the user the opportunity to manually set these, although this must be done with caution, abiding by the rules given below. All notions of orthogonality and orthonormality are derived from the inner product specified by the orthogonalization manager.

Postcondition:
isInitialized() == true (see post-conditions of isInitialize())

The user has the option of specifying any component of the state using initialize(). However, these arguments are assumed to match the post-conditions specified under isInitialized(). Any necessary component of the state not given to initialize() will be generated.

Note:
For any pointer in newstate which directly points to the multivectors in the solver, the data is not copied.

Implements Belos::GmresIteration< ScalarType, MV, OP >.

Definition at line 564 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
void Belos::BlockGmresIter< ScalarType, MV, OP >::initialize ( ) [inline, virtual]

Initialize the solver with the initial vectors from the linear problem or random data.

Implements Belos::Iteration< ScalarType, MV, OP >.

Definition at line 170 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
GmresIterationState<ScalarType,MV> Belos::BlockGmresIter< ScalarType, MV, OP >::getState ( ) const [inline, virtual]

Get the current state of the linear solver.

The data is only valid if isInitialized() == true.

Returns:
A GmresIterationState object containing const pointers to the current solver state.

Implements Belos::GmresIteration< ScalarType, MV, OP >.

Definition at line 183 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
int Belos::BlockGmresIter< ScalarType, MV, OP >::getNumIters ( ) const [inline, virtual]

Get the current iteration count.

Implements Belos::Iteration< ScalarType, MV, OP >.

Definition at line 200 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
void Belos::BlockGmresIter< ScalarType, MV, OP >::resetNumIters ( int  iter = 0) [inline, virtual]

Reset the iteration count.

Implements Belos::Iteration< ScalarType, MV, OP >.

Definition at line 203 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
Teuchos::RCP< const MV > Belos::BlockGmresIter< ScalarType, MV, OP >::getNativeResiduals ( std::vector< MagnitudeType > *  norms) const

Get the norms of the residuals native to the solver.

Returns:
A std::vector of length blockSize containing the native residuals.

Definition at line 542 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
Teuchos::RCP< MV > Belos::BlockGmresIter< ScalarType, MV, OP >::getCurrentUpdate ( ) const [virtual]

Get the current update to the linear system.

Note:
Some solvers, like GMRES, do not compute updates to the solution every iteration. This method forces its computation. Other solvers, like CG, update the solution each iteration, so this method will return a zero std::vector indicating that the linear problem contains the current solution.

Implements Belos::Iteration< ScalarType, MV, OP >.

Definition at line 500 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
void Belos::BlockGmresIter< ScalarType, MV, OP >::updateLSQR ( int  dim = -1) [virtual]

Method for updating QR factorization of upper Hessenberg matrix.

Note:
If dim >= getCurSubspaceDim() and dim < getMaxSubspaceDim(), then the dim-th equations of the least squares problem will be updated.

Implements Belos::GmresIteration< ScalarType, MV, OP >.

Definition at line 768 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
int Belos::BlockGmresIter< ScalarType, MV, OP >::getCurSubspaceDim ( ) const [inline, virtual]

Get the dimension of the search subspace used to generate the current solution to the linear problem.

Implements Belos::GmresIteration< ScalarType, MV, OP >.

Definition at line 224 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
int Belos::BlockGmresIter< ScalarType, MV, OP >::getMaxSubspaceDim ( ) const [inline, virtual]

Get the maximum dimension allocated for the search subspace.

Implements Belos::GmresIteration< ScalarType, MV, OP >.

Definition at line 230 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
const LinearProblem<ScalarType,MV,OP>& Belos::BlockGmresIter< ScalarType, MV, OP >::getProblem ( ) const [inline, virtual]

Get a constant reference to the linear problem.

Implements Belos::Iteration< ScalarType, MV, OP >.

Definition at line 239 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
int Belos::BlockGmresIter< ScalarType, MV, OP >::getBlockSize ( ) const [inline, virtual]

Get the blocksize to be used by the iterative solver in solving this linear problem.

Implements Belos::Iteration< ScalarType, MV, OP >.

Definition at line 242 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
void Belos::BlockGmresIter< ScalarType, MV, OP >::setBlockSize ( int  blockSize) [inline, virtual]

Set the blocksize.

Implements Belos::Iteration< ScalarType, MV, OP >.

Definition at line 245 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
int Belos::BlockGmresIter< ScalarType, MV, OP >::getNumBlocks ( ) const [inline]

Get the maximum number of blocks used by the iterative solver in solving this linear problem.

Definition at line 248 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
void Belos::BlockGmresIter< ScalarType, MV, OP >::setNumBlocks ( int  numBlocks) [inline]

Set the maximum number of blocks used by the iterative solver.

Definition at line 251 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
void Belos::BlockGmresIter< ScalarType, MV, OP >::setSize ( int  blockSize,
int  numBlocks 
) [virtual]

Set the blocksize and number of blocks to be used by the iterative solver in solving this linear problem.

Changing either the block size or the number of blocks will reset the solver to an uninitialized state.

Implements Belos::GmresIteration< ScalarType, MV, OP >.

Definition at line 377 of file BelosBlockGmresIter.hpp.

template<class ScalarType , class MV , class OP >
bool Belos::BlockGmresIter< ScalarType, MV, OP >::isInitialized ( ) [inline, virtual]

States whether the solver has been initialized or not.

Implements Belos::Iteration< ScalarType, MV, OP >.

Definition at line 262 of file BelosBlockGmresIter.hpp.


The documentation for this class was generated from the following file:
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