SolverControl Class Reference

#include <deal.II/lac/solver_control.h>

Inheritance diagram for SolverControl:

Classes
class	NoConvergence

Public Types
enum	State { iterate = 0, success, failure }

Public Member Functions
	SolverControl (const unsigned int n=100, const double tol=1.e-10, const bool log_history=false, const bool log_result=true)
virtual	~SolverControl ()=default
void	parse_parameters (ParameterHandler &param)
virtual State	check (const unsigned int step, const double check_value)
State	last_check () const
double	initial_value () const
double	last_value () const
unsigned int	last_step () const
unsigned int	max_steps () const
unsigned int	set_max_steps (const unsigned int)
void	set_failure_criterion (const double rel_failure_residual)
void	clear_failure_criterion ()
double	tolerance () const
double	set_tolerance (const double)
void	enable_history_data ()
const std::vector< double > &	get_history_data () const
double	average_reduction () const
double	final_reduction () const
double	step_reduction (unsigned int step) const
void	log_history (const bool)
bool	log_history () const
unsigned int	log_frequency (unsigned int)
void	log_result (const bool)
bool	log_result () const
Public Member Functions inherited from Subscriptor
	Subscriptor ()
	Subscriptor (const Subscriptor &)
	Subscriptor (Subscriptor &&) noexcept
virtual	~Subscriptor ()
Subscriptor &	operator= (const Subscriptor &)
Subscriptor &	operator= (Subscriptor &&) noexcept
void	subscribe (const char *identifier=nullptr) const
void	unsubscribe (const char *identifier=nullptr) const
unsigned int	n_subscriptions () const
void	list_subscribers () const
template<class Archive >
void	serialize (Archive &ar, const unsigned int version)

Static Public Member Functions
static void	declare_parameters (ParameterHandler &param)
static ::ExceptionBase &	ExcHistoryDataRequired ()
Static Public Member Functions inherited from Subscriptor
static ::ExceptionBase &	ExcInUse (int arg1, std::string arg2, std::string arg3)
static ::ExceptionBase &	ExcNoSubscriber (std::string arg1, std::string arg2)

Protected Attributes
unsigned int	maxsteps
double	tol
State	lcheck
double	initial_val
double	lvalue
unsigned int	lstep
bool	check_failure
double	relative_failure_residual
double	failure_residual
bool	m_log_history
unsigned int	m_log_frequency
bool	m_log_result
bool	history_data_enabled
std::vector< double >	history_data

Detailed Description

Control class to determine convergence of iterative solvers.

Used by iterative methods to determine whether the iteration should be continued. To this end, the virtual function check() is called in each iteration with the current iteration step and the value indicating convergence (usually the residual).

After the iteration has terminated, the functions last_value() and last_step() can be used to obtain information about the final state of the iteration.

check() can be replaced in derived classes to allow for more sophisticated tests.

State

The return states of the check function are of type State, which is an enum local to this class. It indicates the state the solver is in.

The possible values of State are

• iterate = 0: continue the iteration.
• success: the goal is reached, the iterative method can terminate successfully.
• failure: the iterative method should stop because convergence could not be achieved or at least was not achieved within the given maximal number of iterations.

Author

Guido Kanschat

Definition at line 64 of file solver_control.h.

Member Enumeration Documentation

State

enum SolverControl::State

Enum denoting the different states a solver can be in. See the general documentation of this class for more information.

Enumerator
iterate	Continue iteration.
success	Stop iteration, goal reached.
failure	Stop iteration, goal not reached.

Definition at line 72 of file solver_control.h.

Constructor & Destructor Documentation

SolverControl()

SolverControl::SolverControl	(	const unsigned int	n = 100,
		const double	tol = 1.e-10,
		const bool	log_history = false,
		const bool	log_result = true
	)

Constructor. The parameters n and tol are the maximum number of iteration steps before failure and the tolerance to determine success of the iteration.

log_history specifies whether the history (i.e. the value to be checked and the number of the iteration step) shall be printed to deallog stream. Default is: do not print. Similarly, log_result specifies the whether the final result is logged to deallog. Default is yes.

Definition at line 29 of file solver_control.cc.

~SolverControl()

virtual SolverControl::~SolverControl ( )

virtualdefault

Virtual destructor is needed as there are virtual functions in this class.

Member Function Documentation

declare_parameters()

void SolverControl::declare_parameters ( ParameterHandler &  param )

static

Interface to parameter file.

Definition at line 204 of file solver_control.cc.

parse_parameters()

void SolverControl::parse_parameters

(

ParameterHandler &

param

)

Read parameters from file.

Definition at line 214 of file solver_control.cc.

check()

SolverControl::State SolverControl::check ( const unsigned int  step, const double  check_value  )

virtual

Decide about success or failure of an iteration. This function gets the current iteration step to determine, whether the allowed number of steps has been exceeded and returns failure in this case. If check_value is below the prescribed tolerance, it returns success. In all other cases iterate is returned to suggest continuation of the iterative procedure.

The iteration is also aborted if the residual becomes a denormalized value (NaN).

check() additionally preserves step and check_value. These values are accessible by last_value() and last_step().

Derived classes may overload this function, e.g. to log the convergence indicators (check_value) or to do other computations.

Reimplemented in ConsecutiveControl, IterationNumberControl, and ReductionControl.

Definition at line 52 of file solver_control.cc.

last_check()

SolverControl::State SolverControl::last_check

(

)

const

Return the result of the last check operation.

Definition at line 109 of file solver_control.cc.

initial_value()

double SolverControl::initial_value

(

)

const

Return the initial convergence criterion.

Definition at line 116 of file solver_control.cc.

last_value()

double SolverControl::last_value

(

)

const

Return the convergence value of last iteration step for which check was called by the solver.

Definition at line 123 of file solver_control.cc.

last_step()

unsigned int SolverControl::last_step

(

)

const

Number of last iteration step.

Definition at line 130 of file solver_control.cc.

max_steps()

unsigned int SolverControl::max_steps

(

)

const

Maximum number of steps.

set_max_steps()

unsigned int SolverControl::set_max_steps

(

const unsigned

int

)

Change maximum number of steps.

set_failure_criterion()

void SolverControl::set_failure_criterion

(

const double

rel_failure_residual

)

Enables the failure check. Solving is stopped with ReturnState failure if residual>failure_residual with failure_residual:=rel_failure_residual*first_residual.

clear_failure_criterion()

void SolverControl::clear_failure_criterion

(

)

Disables failure check and resets relative_failure_residual and failure_residual to zero.

tolerance()

double SolverControl::tolerance

(

)

const

Tolerance.

set_tolerance()

double SolverControl::set_tolerance

(

const double

)

Change tolerance.

enable_history_data()

void SolverControl::enable_history_data

(

)

Enables writing residuals of each step into a vector for later analysis.

Definition at line 148 of file solver_control.cc.

get_history_data()

const std::vector< double > & SolverControl::get_history_data

(

)

const

Provide read access to the collected residual data.

Definition at line 155 of file solver_control.cc.

average_reduction()

double SolverControl::average_reduction

(

)

const

Average error reduction over all steps.

Requires enable_history_data()

Definition at line 169 of file solver_control.cc.

final_reduction()

double SolverControl::final_reduction

(

)

const

Error reduction of the last step; for stationary iterations, this approximates the norm of the iteration matrix.

Requires enable_history_data()

Definition at line 197 of file solver_control.cc.

step_reduction()

double SolverControl::step_reduction

(

unsigned int

step

)

const

Error reduction of any iteration step.

Requires enable_history_data()

Definition at line 185 of file solver_control.cc.

log_history() [1/2]

void SolverControl::log_history

(

const bool

)

Log each iteration step. Use log_frequency for skipping steps.

log_history() [2/2]

bool SolverControl::log_history

(

)

const

Return the log_history flag.

log_frequency()

unsigned int SolverControl::log_frequency

(

unsigned int

f

)

Set logging frequency.

Definition at line 137 of file solver_control.cc.

log_result() [1/2]

void SolverControl::log_result

(

const bool

)

Log start and end step.

log_result() [2/2]

bool SolverControl::log_result

(

)

const

Return the log_result flag.

Member Data Documentation

maxsteps

unsigned int SolverControl::maxsteps

protected

Maximum number of steps.

Definition at line 311 of file solver_control.h.

tol

double SolverControl::tol

protected

Prescribed tolerance to be achieved.

Definition at line 316 of file solver_control.h.

lcheck

State SolverControl::lcheck

protected

Result of last check operation.

Definition at line 321 of file solver_control.h.

initial_val

double SolverControl::initial_val

protected

Initial value.

Definition at line 326 of file solver_control.h.

lvalue

double SolverControl::lvalue

protected

Last value of the convergence criterion.

Definition at line 331 of file solver_control.h.

lstep

unsigned int SolverControl::lstep

protected

Last step.

Definition at line 336 of file solver_control.h.

check_failure

bool SolverControl::check_failure

protected

Is set to true by set_failure_criterion and enables failure checking.

Definition at line 342 of file solver_control.h.

relative_failure_residual

double SolverControl::relative_failure_residual

protected

Stores the rel_failure_residual set by set_failure_criterion

Definition at line 347 of file solver_control.h.

failure_residual

double SolverControl::failure_residual

protected

failure_residual equals the first residual multiplied by relative_crit set by set_failure_criterion (see there).

Until the first residual is known it is 0.

Definition at line 355 of file solver_control.h.

m_log_history

bool SolverControl::m_log_history

protected

Log convergence history to deallog.

Definition at line 360 of file solver_control.h.

m_log_frequency

unsigned int SolverControl::m_log_frequency

protected

Log only every nth step.

Definition at line 365 of file solver_control.h.

m_log_result

bool SolverControl::m_log_result

protected

Log iteration result to deallog. If true, after finishing the iteration, a statement about failure or success together with lstep and lvalue are logged.

Definition at line 372 of file solver_control.h.

history_data_enabled

bool SolverControl::history_data_enabled

protected

Control over the storage of history data. Set by enable_history_data().

Definition at line 377 of file solver_control.h.

history_data

std::vector<double> SolverControl::history_data

protected

Vector storing the result after each iteration step for later statistical analysis.

Use of this vector is enabled by enable_history_data().

Definition at line 385 of file solver_control.h.

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

• deal.II/lac/solver_control.h
• source/lac/solver_control.cc