Algorithms::TimestepControl Class Reference

#include <deal.II/algorithms/timestep_control.h>

Inheritance diagram for Algorithms::TimestepControl:

Public Member Functions
	TimestepControl (double start=0., double final=1., double tolerance=1.e-2, double start_step=1.e-2, double print_step=-1., double max_step=1.)
void	parse_parameters (const ParameterHandler &param)
double	start () const
double	final () const
double	tolerance () const
double	step () const
double	now () const
bool	advance ()
void	start (double)
void	final (double)
void	tolerance (double)
void	start_step (const double step)
void	max_step (double)
void	restart ()
bool	print ()
template<class Archive >
void	serialize (Archive &ar, const unsigned int version)
EnableObserverPointer functionality
Classes derived from EnableObserverPointer provide a facility to subscribe to this object. This is mostly used by the ObserverPointer 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 void	declare_parameters (ParameterHandler &param)
static ::ExceptionBase &	ExcInUse (int arg1, std::string arg2, std::string arg3)
static ::ExceptionBase &	ExcNoSubscriber (std::string arg1, std::string arg2)

Private Types
using	map_value_type = decltype(counter_map)::value_type
using	map_iterator = decltype(counter_map)::iterator

Private Member Functions
void	check_no_subscribers () const noexcept

Private Attributes
double	start_val
double	final_val
double	tolerance_val
double	start_step_val
double	max_step_val
double	min_step_val
double	current_step_val
double	step_val
double	now_val
double	print_step
double	next_print_val
std::atomic< unsigned int >	counter
std::map< std::string, unsigned int >	counter_map
std::vector< std::atomic< bool > * >	validity_pointers
const std::type_info *	object_info

Static Private Attributes
static std::mutex	mutex

Detailed Description

Control class for timestepping schemes. Its main task is determining the size of the next time step and the according point in the time interval. Additionally, it controls writing the solution to a file.

The size of the next time step is determined as follows:

1. According to the strategy, the step size is tentatively added to the current time.
2. If the resulting time exceeds the final time of the interval, the step size is reduced in order to meet this time.
3. If the resulting time is below the final time by just a fraction of the step size, the step size is increased in order to meet this time.
4. The resulting step size is used from the current time.

The variable print_step can be used to control the amount of output generated by the timestepping scheme.

Note

Many of the features of this class are available in DiscreteTime with a more modern interface and better programming guarantees. Consider using DiscreteTime instead of TimestepControl.

Definition at line 60 of file timestep_control.h.

Member Typedef Documentation

map_value_type

using EnableObserverPointer::map_value_type = decltype(counter_map)::value_type

privateinherited

The data type used in counter_map.

Definition at line 238 of file enable_observer_pointer.h.

map_iterator

using EnableObserverPointer::map_iterator = decltype(counter_map)::iterator

privateinherited

The iterator type used in counter_map.

Definition at line 243 of file enable_observer_pointer.h.

Constructor & Destructor Documentation

TimestepControl()

Algorithms::TimestepControl::TimestepControl	(	double	start = 0.,
		double	final = 1.,
		double	tolerance = 1.e-2,
		double	start_step = 1.e-2,
		double	print_step = -1.,
		double	max_step = 1.
	)

Constructor setting default values

Definition at line 24 of file timestep_control.cc.

Member Function Documentation

declare_parameters()

void Algorithms::TimestepControl::declare_parameters ( ParameterHandler &  param )

static

Declare the control parameters for parameter handler.

Definition at line 50 of file timestep_control.cc.

parse_parameters()

void Algorithms::TimestepControl::parse_parameters

(

const ParameterHandler &

param

)

Read the control parameters from a parameter handler.

This function also calls restart() to reset all other internal parameters of this class to their appropriate values based on the parameters just read.

Definition at line 63 of file timestep_control.cc.

start() [1/2]

double Algorithms::TimestepControl::start ( ) const

inline

Return the left end of the time interval.

Definition at line 231 of file timestep_control.h.

final() [1/2]

double Algorithms::TimestepControl::final ( ) const

inline

Return the right end of the time interval. The control mechanism ensures that the final time step ends at this point.

Definition at line 238 of file timestep_control.h.

tolerance() [1/2]

double Algorithms::TimestepControl::tolerance ( ) const

inline

Return the tolerance value controlling the time steps.

Definition at line 252 of file timestep_control.h.

step()

double Algorithms::TimestepControl::step ( ) const

inline

Return the size of the current time step.

Definition at line 245 of file timestep_control.h.

now()

double Algorithms::TimestepControl::now ( ) const

inline

Return the current time.

Definition at line 259 of file timestep_control.h.

advance()

bool Algorithms::TimestepControl::advance

(

)

Compute the size of the next step and return true if it differs from the current step size. Advance the current time by the new step size.

Definition at line 76 of file timestep_control.cc.

start() [2/2]

void Algorithms::TimestepControl::start ( double  t )

inline

Set start value.

Definition at line 266 of file timestep_control.h.

final() [2/2]

void Algorithms::TimestepControl::final ( double  t )

inline

Set final time value.

Definition at line 273 of file timestep_control.h.

tolerance() [2/2]

void Algorithms::TimestepControl::tolerance ( double  t )

inline

Set tolerance

Definition at line 280 of file timestep_control.h.

start_step()

void Algorithms::TimestepControl::start_step ( const double  step )

inline

Set size of the first step. This may be overwritten by the time stepping strategy.

Parameters

[in]

step

The size of the first step, which may be overwritten by the time stepping strategy.

Definition at line 287 of file timestep_control.h.

max_step()

void Algorithms::TimestepControl::max_step ( double  t )

inline

Set size of the maximum step size.

Definition at line 294 of file timestep_control.h.

restart()

void Algorithms::TimestepControl::restart ( )

inline

Set now() equal to start(). Initialize step() and print() to their initial values.

Definition at line 301 of file timestep_control.h.

print()

bool Algorithms::TimestepControl::print

(

)

Return true if this timestep should be written to disk.

Definition at line 101 of file timestep_control.cc.

subscribe()

void EnableObserverPointer::subscribe ( std::atomic< bool > *const  validity, const std::string &  identifier = ""  ) const

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 131 of file enable_observer_pointer.cc.

unsubscribe()

void EnableObserverPointer::unsubscribe ( std::atomic< bool > *const  validity, const std::string &  identifier = ""  ) const

inherited

Unsubscribes a user from the object.

Note

The identifier and the validity pointer must be the same as the one supplied to subscribe().

Definition at line 151 of file enable_observer_pointer.cc.

n_subscriptions()

unsigned int EnableObserverPointer::n_subscriptions ( ) const

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 322 of file enable_observer_pointer.h.

list_subscribers() [1/2]

template<typename StreamType >

void EnableObserverPointer::list_subscribers ( StreamType &  stream ) const

inlineinherited

List the subscribers to the input stream.

Definition at line 339 of file enable_observer_pointer.h.

list_subscribers() [2/2]

void EnableObserverPointer::list_subscribers ( ) const

inherited

List the subscribers to deallog.

Definition at line 199 of file enable_observer_pointer.cc.

serialize()

template<class Archive >

void EnableObserverPointer::serialize ( Archive &  ar, const unsigned int  version  )

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 331 of file enable_observer_pointer.h.

check_no_subscribers()

void EnableObserverPointer::check_no_subscribers ( ) const

privatenoexceptinherited

Check that there are no objects subscribing to this object. If this check passes then it is safe to destroy the current object. It this check fails then this function will either abort or print an error message to deallog (by using the AssertNothrow mechanism), but will not throw an exception.

Note

Since this function is just a consistency check it does nothing in release mode.

If this function is called when there is an uncaught exception then, rather than aborting, this function prints an error message to the standard error stream and returns.

Definition at line 53 of file enable_observer_pointer.cc.

Member Data Documentation

start_val

double Algorithms::TimestepControl::start_val

private

The beginning of the time interval.

Definition at line 173 of file timestep_control.h.

final_val

double Algorithms::TimestepControl::final_val

private

The end of the time interval.

Definition at line 178 of file timestep_control.h.

tolerance_val

double Algorithms::TimestepControl::tolerance_val

private

The tolerance value controlling the time steps.

Definition at line 183 of file timestep_control.h.

start_step_val

double Algorithms::TimestepControl::start_step_val

private

The size of the first step.

Definition at line 188 of file timestep_control.h.

max_step_val

double Algorithms::TimestepControl::max_step_val

private

The maximum step size.

Definition at line 193 of file timestep_control.h.

min_step_val

double Algorithms::TimestepControl::min_step_val

private

The minimum step size.

Definition at line 198 of file timestep_control.h.

current_step_val

double Algorithms::TimestepControl::current_step_val

private

The size of the current time step. This may differ from step_val, if we aim at final_val.

Definition at line 204 of file timestep_control.h.

step_val

double Algorithms::TimestepControl::step_val

private

The size of the current time step determined by the strategy. This may differ from current_step_val, if we aim at final_val.

Definition at line 210 of file timestep_control.h.

now_val

double Algorithms::TimestepControl::now_val

private

The current time.

Definition at line 215 of file timestep_control.h.

print_step

double Algorithms::TimestepControl::print_step

private

Determines the approximate time interval between generated outputs. If negative, output will be generated at all time steps.

Definition at line 221 of file timestep_control.h.

next_print_val

double Algorithms::TimestepControl::next_print_val

private

If current time exceeds this value, it is time to generate the output.

Definition at line 226 of file timestep_control.h.

counter

std::atomic<unsigned int> EnableObserverPointer::counter

mutableprivateinherited

Store the number of objects which subscribed to this object. Initially, this number is zero, and upon destruction it shall be zero again (i.e. all objects which subscribed should have unsubscribed again).

The creator (and owner) of an object is counted in the map below if HE manages to supply identification.

We use the mutable keyword in order to allow subscription to constant objects also.

This counter may be read from and written to concurrently in multithreaded code: hence we use the std::atomic class template.

Definition at line 227 of file enable_observer_pointer.h.

counter_map

std::map<std::string, unsigned int> EnableObserverPointer::counter_map

mutableprivateinherited

In this map, we count subscriptions for each different identification string supplied to subscribe().

Definition at line 233 of file enable_observer_pointer.h.

validity_pointers

std::vector<std::atomic<bool> *> EnableObserverPointer::validity_pointers

mutableprivateinherited

In this vector, we store pointers to the validity bool in the ObserverPointer objects that subscribe to this class.

Definition at line 249 of file enable_observer_pointer.h.

object_info

const std::type_info* EnableObserverPointer::object_info

mutableprivateinherited

Pointer to the typeinfo object of this object, from which we can later deduce the class name. Since this information on the derived class is neither available in the destructor, nor in the constructor, we obtain it in between and store it here.

Definition at line 257 of file enable_observer_pointer.h.

mutex

std::mutex EnableObserverPointer::mutex

staticprivateinherited

A mutex used to ensure data consistency when accessing the mutable members of this class. This lock is used in the subscribe() and unsubscribe() functions, as well as in list_subscribers().

Definition at line 280 of file enable_observer_pointer.h.

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

• include/deal.II/algorithms/timestep_control.h
• source/algorithms/timestep_control.cc