Accelerated flexible conjugate gradient method. More...

#include <dune/istl/solvers.hh>

Public Types
typedef X	domain_type
	Type of the domain of the operator to be inverted.

typedef X	range_type
	Type of the range of the operator to be inverted.

typedef X::field_type	field_type
	The field type of the operator.

typedef FieldTraits< field_type >::real_type	real_type
	The real type of the field type (is the same if using real numbers, but differs for std::complex)

typedef Simd::Scalar< real_type >	scalar_real_type
	scalar type underlying the field_type

Public Member Functions
	RestartedFCGSolver (const LinearOperator< X, X > &op, Preconditioner< X, X > &prec, scalar_real_type reduction, int maxit, int verbose, int mmax=10)
	Constructor to initialize a RestartedFCG solver. More...

	RestartedFCGSolver (const LinearOperator< X, X > &op, const ScalarProduct< X > &sp, Preconditioner< X, X > &prec, scalar_real_type reduction, int maxit, int verbose, int mmax=10)
	Constructor to initialize a RestartedFCG solver. More...

	RestartedFCGSolver (std::shared_ptr< const LinearOperator< X, X > > op, std::shared_ptr< const ScalarProduct< X > > sp, std::shared_ptr< Preconditioner< X, X > > prec, scalar_real_type reduction, int maxit, int verbose, int mmax=10)
	Constructor to initialize a RestartedFCG solver. More...

	RestartedFCGSolver (std::shared_ptr< const LinearOperator< X, X > > op, std::shared_ptr< Preconditioner< X, X > > prec, const ParameterTree &config)
	Constructor. More...

void	apply (X &x, X &b, InverseOperatorResult &res) override
	Apply inverse operator. More...

void	apply (X &x, X &b, double reduction, InverseOperatorResult &res) override
	Apply inverse operator with given reduction factor. More...

SolverCategory::Category	category () const override
	Category of the solver (see SolverCategory::Category)

Protected Member Functions
void	printHeader (std::ostream &s) const
	helper function for printing header of solver output

void	printOutput (std::ostream &s, const CountType &iter, const DataType &norm, const DataType &norm_old) const
	helper function for printing solver output

void	printOutput (std::ostream &s, const CountType &iter, const DataType &norm) const
	helper function for printing solver output

Detailed Description

template<class X>
class Dune::RestartedFCGSolver< X >

Accelerated flexible conjugate gradient method.

Flexible conjugate gradient method as in Y. Notay 'Flexible conjugate Gradients', SIAM J. Sci. Comput Vol. 22, No.4, pp. 1444-1460

This solver discard cyclic all old directions to speed up computing. In exact arithmetic it is exactly the same as the GeneralizedPCGSolver, but it is much faster, depending on the operator and dimension. On the other hand for large mmax it uses noticeably more memory.

Constructor & Destructor Documentation

◆ RestartedFCGSolver() [1/4]

template<class X >

Dune::RestartedFCGSolver< X >::RestartedFCGSolver	(	const LinearOperator< X, X > &	op,
		Preconditioner< X, X > &	prec,
		scalar_real_type	reduction,
		int	maxit,
		int	verbose,
		int	mmax = `10`
	)

inline

Constructor to initialize a RestartedFCG solver.

Parameters

mmax	is the maximal number of previous vectors which are orthogonalized against the new search direction.

◆ RestartedFCGSolver() [2/4]

template<class X >

Dune::RestartedFCGSolver< X >::RestartedFCGSolver	(	const LinearOperator< X, X > &	op,
		const ScalarProduct< X > &	sp,
		Preconditioner< X, X > &	prec,
		scalar_real_type	reduction,
		int	maxit,
		int	verbose,
		int	mmax = `10`
	)

inline

Constructor to initialize a RestartedFCG solver.

Parameters

mmax	is the maximal number of previous vectors which are orthogonalized against the new search direction.

◆ RestartedFCGSolver() [3/4]

template<class X >

Dune::RestartedFCGSolver< X >::RestartedFCGSolver	(	std::shared_ptr< const LinearOperator< X, X > >	op,
		std::shared_ptr< const ScalarProduct< X > >	sp,
		std::shared_ptr< Preconditioner< X, X > >	prec,
		scalar_real_type	reduction,
		int	maxit,
		int	verbose,
		int	mmax = `10`
	)

inline

Constructor to initialize a RestartedFCG solver.

Parameters

mmax	is the maximal number of previous vectors which are orthogonalized against the new search direction.

◆ RestartedFCGSolver() [4/4]

template<class X >

Dune::RestartedFCGSolver< X >::RestartedFCGSolver	(	std::shared_ptr< const LinearOperator< X, X > >	op,
		std::shared_ptr< Preconditioner< X, X > >	prec,
		const ParameterTree &	config
	)

inline

Constructor.

Additional parameter:

ParameterTree Key	Meaning
mmax	number of FCG cycles before restart. default=10

See ISTL_Factory for the ParameterTree layout and examples.

Member Function Documentation

◆ apply() [1/2]

void Dune::IterativeSolver< X, X >::apply	(	X &	x,
		X &	b,
		double	reduction,
		InverseOperatorResult &	res
	)

inlineoverridevirtualinherited

Apply inverse operator with given reduction factor.

apply inverse operator, with given convergence criteria.

Warning: Right hand side b may be overwritten!

Parameters

x	The left hand side to store the result in.
b	The right hand side
reduction	The minimum defect reduction to achieve.
res	Object to store the statistics about applying the operator.

Exceptions

SolverAbort When the solver detects a problem and cannot continue

Implements Dune::InverseOperator< X, X >.

Reimplemented in Dune::RestartedGMResSolver< X, X >.

◆ apply() [2/2]

template<class X >

void Dune::RestartedFCGSolver< X >::apply	(	X &	x,
		X &	b,
		InverseOperatorResult &	res
	)

inlineoverridevirtual

Apply inverse operator.

Apply inverse operator,.

Warning: Note: right hand side b may be overwritten!

Parameters

x	The left hand side to store the result in.
b	The right hand side
res	Object to store the statistics about applying the operator.

Exceptions

SolverAbort When the solver detects a problem and cannot continue

Note: Currently, the RestartedFCGSolver aborts when a NaN or infinite defect is detected. However, -ffinite-math-only (implied by -ffast-math) can inhibit a result from becoming NaN that really should be NaN. E.g. numeric_limits<double>::quiet_NaN()*0.0==0.0 with gcc-5.3 -ffast-math.

Implements Dune::InverseOperator< X, X >.

Reimplemented in Dune::CompleteFCGSolver< X >.

References Dune::InverseOperatorResult::clear(), and Dune::InverseOperatorResult::converged.

Referenced by Dune::CompleteFCGSolver< X >::apply().

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