The conjugate gradient method. More...

#include <iterative_linear_solver.h>

Inheritance diagram for oomph::CG< MATRIX >:

Public Member Functions
	CG ()
	Constructor.

virtual	~CG ()
	Destructor (cleanup storage)

	CG (const CG &)=delete
	Broken copy constructor.

void	operator= (const CG &)=delete
	Broken assignment operator.

void	disable_resolve ()
	Overload disable resolve so that it cleans up memory too.

void	solve (Problem *const &problem_pt, DoubleVector &result)
	Solver: Takes pointer to problem and returns the results vector which contains the solution of the linear system defined by the problem's fully assembled Jacobian and residual vector.

void	solve (DoubleMatrixBase *const &matrix_pt, const DoubleVector &rhs, DoubleVector &solution)
	Linear-algebra-type solver: Takes pointer to a matrix and rhs vector and returns the solution of the linear system.

void	resolve (const DoubleVector &rhs, DoubleVector &result)
	Re-solve the system defined by the last assembled Jacobian and the rhs vector specified here. Solution is returned in the vector result.

unsigned	iterations () const
	Number of iterations taken.

Public Member Functions inherited from oomph::IterativeLinearSolver
	IterativeLinearSolver ()
	Constructor: Set (default) trivial preconditioner and set defaults for tolerance and max. number of iterations.

	IterativeLinearSolver (const IterativeLinearSolver &)=delete
	Broken copy constructor.

void	operator= (const IterativeLinearSolver &)=delete
	Broken assignment operator.

virtual	~IterativeLinearSolver ()
	Destructor (empty)

Preconditioner *&	preconditioner_pt ()
	Access function to preconditioner.

Preconditioner *const &	preconditioner_pt () const
	Access function to preconditioner (const version)

double &	tolerance ()
	Access to convergence tolerance.

unsigned &	max_iter ()
	Access to max. number of iterations.

void	enable_doc_convergence_history ()
	Enable documentation of the convergence history.

void	disable_doc_convergence_history ()
	Disable documentation of the convergence history.

void	open_convergence_history_file_stream (const std::string &file_name, const std::string &zone_title="")
	Write convergence history into file with specified filename (automatically switches on doc). Optional second argument is a string that can be used (as a zone title) to identify what case we're running (e.g. what combination of linear solver and preconditioner or parameter values are used).

void	close_convergence_history_file_stream ()
	Close convergence history output stream.

double	jacobian_setup_time () const
	returns the time taken to assemble the jacobian matrix and residual vector

double	linear_solver_solution_time () const
	return the time taken to solve the linear system

virtual double	preconditioner_setup_time () const
	returns the the time taken to setup the preconditioner

void	enable_setup_preconditioner_before_solve ()
	Setup the preconditioner before the solve.

void	disable_setup_preconditioner_before_solve ()
	Don't set up the preconditioner before the solve.

void	enable_error_after_max_iter ()
	Throw an error if we don't converge within max_iter.

void	disable_error_after_max_iter ()
	Don't throw an error if we don't converge within max_iter (default).

void	enable_iterative_solver_as_preconditioner ()
	Enables the iterative solver be used as preconditioner (when calling the solve method it bypass the setup solver method – currently only used by Trilinos solver —)

void	disable_iterative_solver_as_preconditioner ()
	Disables the iterative solver be used as preconditioner (when calling the solve method it bypass the setup solver method – currently only used by Trilinos solver —)

Public Member Functions inherited from oomph::LinearSolver
	LinearSolver ()
	Empty constructor, initialise the member data.

	LinearSolver (const LinearSolver &dummy)=delete
	Broken copy constructor.

void	operator= (const LinearSolver &)=delete
	Broken assignment operator.

virtual	~LinearSolver ()
	Empty virtual destructor.

void	enable_doc_time ()
	Enable documentation of solve times.

void	disable_doc_time ()
	Disable documentation of solve times.

bool	is_doc_time_enabled () const
	Is documentation of solve times enabled?

bool	is_resolve_enabled () const
	Boolean flag indicating if resolves are enabled.

virtual void	enable_resolve ()
	Enable resolve (i.e. store matrix and/or LU decomposition, say) Virtual so it can be overloaded to perform additional tasks.

virtual void	solve (DoubleMatrixBase *const &matrix_pt, const Vector< double > &rhs, Vector< double > &result)
	Linear-algebra-type solver: Takes pointer to a matrix and rhs vector and returns the solution of the linear system.

virtual void	solve_transpose (Problem *const &problem_pt, DoubleVector &result)
	Solver: Takes pointer to problem and returns the results vector which contains the solution of the linear system defined by the problem's fully assembled Jacobian and residual vector (broken virtual).

virtual void	solve_transpose (DoubleMatrixBase *const &matrix_pt, const DoubleVector &rhs, DoubleVector &result)
	Linear-algebra-type solver: Takes pointer to a matrix and rhs vector and returns the solution of the linear system.

virtual void	solve_transpose (DoubleMatrixBase *const &matrix_pt, const Vector< double > &rhs, Vector< double > &result)
	Linear-algebra-type solver: Takes pointer to a matrix and rhs vector and returns the solution of the linear system.

virtual void	resolve_transpose (const DoubleVector &rhs, DoubleVector &result)
	Solver: Resolve the system defined by the last assembled jacobian and the rhs vector. Solution is returned in the vector result. (broken virtual)

virtual void	enable_computation_of_gradient ()
	function to enable the computation of the gradient required for the globally convergent Newton method

void	disable_computation_of_gradient ()
	function to disable the computation of the gradient required for the globally convergent Newton method

void	reset_gradient ()
	function to reset the size of the gradient before each Newton solve

void	get_gradient (DoubleVector &gradient)
	function to access the gradient, provided it has been computed

Public Member Functions inherited from oomph::DistributableLinearAlgebraObject
	DistributableLinearAlgebraObject ()
	Default constructor - create a distribution.

	DistributableLinearAlgebraObject (const DistributableLinearAlgebraObject &matrix)=delete
	Broken copy constructor.

void	operator= (const DistributableLinearAlgebraObject &)=delete
	Broken assignment operator.

virtual	~DistributableLinearAlgebraObject ()
	Destructor.

LinearAlgebraDistribution *	distribution_pt () const
	access to the LinearAlgebraDistribution

unsigned	nrow () const
	access function to the number of global rows.

unsigned	nrow_local () const
	access function for the num of local rows on this processor.

unsigned	nrow_local (const unsigned &p) const
	access function for the num of local rows on this processor.

unsigned	first_row () const
	access function for the first row on this processor

unsigned	first_row (const unsigned &p) const
	access function for the first row on this processor

bool	distributed () const
	distribution is serial or distributed

bool	distribution_built () const
	if the communicator_pt is null then the distribution is not setup then false is returned, otherwise return true

void	build_distribution (const LinearAlgebraDistribution *const dist_pt)
	setup the distribution of this distributable linear algebra object

void	build_distribution (const LinearAlgebraDistribution &dist)
	setup the distribution of this distributable linear algebra object

Private Member Functions
void	solve_helper (DoubleMatrixBase *const &matrix_pt, const DoubleVector &rhs, DoubleVector &solution)
	General interface to solve function.

void	clean_up_memory ()
	Cleanup data that's stored for resolve (if any has been stored)

Private Attributes
unsigned	Iterations
	Number of iterations taken.

MATRIX *	Matrix_pt
	Pointer to matrix.

bool	Resolving
	Boolean flag to indicate if the solve is done in re-solve mode, bypassing setup of matrix and preconditioner.

bool	Matrix_can_be_deleted
	Boolean flag to indicate if the matrix pointed to be Matrix_pt can be deleted.

Additional Inherited Members
Protected Member Functions inherited from oomph::DistributableLinearAlgebraObject
void	clear_distribution ()
	clear the distribution of this distributable linear algebra object

Protected Attributes inherited from oomph::IterativeLinearSolver
bool	Doc_convergence_history
	Flag indicating if the convergence history is to be documented.

std::ofstream	Output_file_stream
	Output file stream for convergence history.

double	Tolerance
	Convergence tolerance.

unsigned	Max_iter
	Maximum number of iterations.

Preconditioner *	Preconditioner_pt
	Pointer to the preconditioner.

double	Jacobian_setup_time
	Jacobian setup time.

double	Solution_time
	linear solver solution time

double	Preconditioner_setup_time
	Preconditioner setup time.

bool	Setup_preconditioner_before_solve
	indicates whether the preconditioner should be setup before solve. Default = true;

bool	Throw_error_after_max_iter
	Should we throw an error instead of just returning when we hit the max iterations?

bool	Use_iterative_solver_as_preconditioner
	Use the iterative solver as preconditioner.

bool	First_time_solve_when_used_as_preconditioner
	When the iterative solver is used a preconditioner then we call the setup of solver method only once (the first time the solve method is called)

Protected Attributes inherited from oomph::LinearSolver
bool	Enable_resolve
	Boolean that indicates whether the matrix (or its factors, in the case of direct solver) should be stored so that the resolve function can be used.

bool	Doc_time
	Boolean flag that indicates whether the time taken.

bool	Compute_gradient
	flag that indicates whether the gradient required for the globally convergent Newton method should be computed or not

bool	Gradient_has_been_computed
	flag that indicates whether the gradient was computed or not

DoubleVector	Gradient_for_glob_conv_newton_solve
	DoubleVector storing the gradient for the globally convergent Newton method.

Static Protected Attributes inherited from oomph::IterativeLinearSolver
static IdentityPreconditioner	Default_preconditioner
	Default preconditioner: The base class for preconditioners is a fully functional (if trivial!) preconditioner.

Detailed Description

template<typename MATRIX>
class oomph::CG< MATRIX >

The conjugate gradient method.

Definition at line 283 of file iterative_linear_solver.h.

Constructor & Destructor Documentation

◆ CG() [1/2]

template<typename MATRIX >

oomph::CG< MATRIX >::CG ( )

inline

Constructor.

Definition at line 287 of file iterative_linear_solver.h.

◆ ~CG()

template<typename MATRIX >

virtual oomph::CG< MATRIX >::~CG ( )

inlinevirtual

Destructor (cleanup storage)

Definition at line 297 of file iterative_linear_solver.h.

References oomph::CG< MATRIX >::clean_up_memory().

◆ CG() [2/2]

template<typename MATRIX >

oomph::CG< MATRIX >::CG ( const CG< MATRIX > & )

delete

Broken copy constructor.

Member Function Documentation

◆ clean_up_memory()

template<typename MATRIX >

void oomph::CG< MATRIX >::clean_up_memory ( )

inlineprivatevirtual

Cleanup data that's stored for resolve (if any has been stored)

Reimplemented from oomph::LinearSolver.

Definition at line 375 of file iterative_linear_solver.h.

References oomph::CG< MATRIX >::Matrix_can_be_deleted, and oomph::CG< MATRIX >::Matrix_pt.

Referenced by oomph::CG< MATRIX >::disable_resolve(), and oomph::CG< MATRIX >::~CG().

◆ disable_resolve()

template<typename MATRIX >

void oomph::CG< MATRIX >::disable_resolve ( )

inlinevirtual

Overload disable resolve so that it cleans up memory too.

Reimplemented from oomph::LinearSolver.

Definition at line 309 of file iterative_linear_solver.h.

References oomph::CG< MATRIX >::clean_up_memory(), and oomph::LinearSolver::disable_resolve().

◆ iterations()

template<typename MATRIX >

unsigned oomph::CG< MATRIX >::iterations ( ) const

inlinevirtual

Number of iterations taken.

Implements oomph::IterativeLinearSolver.

Definition at line 361 of file iterative_linear_solver.h.

References oomph::CG< MATRIX >::Iterations.

◆ operator=()

template<typename MATRIX >

void oomph::CG< MATRIX >::operator= ( const CG< MATRIX > & )

delete

Broken assignment operator.

◆ resolve()

template<typename MATRIX >

void oomph::CG< MATRIX >::resolve	(	const DoubleVector &	rhs,
		DoubleVector &	result
	)

virtual

Re-solve the system defined by the last assembled Jacobian and the rhs vector specified here. Solution is returned in the vector result.

Reimplemented from oomph::LinearSolver.

Definition at line 922 of file iterative_linear_solver.cc.

◆ solve() [1/2]

template<typename MATRIX >

void oomph::CG< MATRIX >::solve	(	DoubleMatrixBase *const &	matrix_pt,
		const DoubleVector &	rhs,
		DoubleVector &	solution
	)

inlinevirtual

Linear-algebra-type solver: Takes pointer to a matrix and rhs vector and returns the solution of the linear system.

Reimplemented from oomph::LinearSolver.

Definition at line 323 of file iterative_linear_solver.h.

References oomph::DistributableLinearAlgebraObject::build_distribution(), oomph::DistributableLinearAlgebraObject::distribution_pt(), oomph::LinearSolver::Enable_resolve, oomph::CG< MATRIX >::Matrix_can_be_deleted, oomph::CG< MATRIX >::Matrix_pt, oomph::CG< MATRIX >::Resolving, and oomph::CG< MATRIX >::solve_helper().

◆ solve() [2/2]

template<typename MATRIX >

void oomph::CG< MATRIX >::solve	(	Problem *const &	problem_pt,
		DoubleVector &	result
	)

virtual

Solver: Takes pointer to problem and returns the results vector which contains the solution of the linear system defined by the problem's fully assembled Jacobian and residual vector.

Implements oomph::LinearSolver.

Definition at line 950 of file iterative_linear_solver.cc.

References oomph::DistributableLinearAlgebraObject::distribution_pt(), oomph::Problem::get_jacobian(), oomph::oomph_info, oomph::TAdvectionDiffusionReactionElement< NREAGENT, DIM, NNODE_1D >::TAdvectionDiffusionReactionElement(), and oomph::TimingHelpers::timer().

◆ solve_helper()

template<typename MATRIX >

void oomph::CG< MATRIX >::solve_helper	(	DoubleMatrixBase *const &	matrix_pt,
		const DoubleVector &	rhs,
		DoubleVector &	solution
	)

private

General interface to solve function.

Linear-algebra-type solver: Takes pointer to a matrix and rhs vector and returns the solution of the linear system. Algorithm and variable names based on "Matrix Computations, 2nd Ed." Golub & van Loan, John Hopkins University Press(1989), page 529.

Definition at line 605 of file iterative_linear_solver.cc.

References oomph::DoubleVector::dot(), i, oomph::DoubleMatrixBase::multiply(), oomph::DoubleMatrixBase::ncol(), oomph::DoubleVector::norm(), oomph::DoubleMatrixBase::nrow(), oomph::oomph_info, oomph::TAdvectionDiffusionReactionElement< NREAGENT, DIM, NNODE_1D >::TAdvectionDiffusionReactionElement(), and oomph::TimingHelpers::timer().

Referenced by oomph::CG< MATRIX >::solve().