Reference documentation for deal.II version GIT 2f5445400b 2023-02-05 22:30:02+00:00
Algorithms::TimestepControl Class Reference

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

Inheritance diagram for Algorithms::TimestepControl:
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## 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 (ParameterHandler &param)

double start () const

double final () const

double tolerance () const

double step () const

double now () const

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)

Subscriptor functionality

Classes derived from Subscriptor provide a facility to subscribe to this object. This is mostly used by the SmartPointer 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 ::ExceptionBaseExcInUse (int arg1, std::string arg2, std::string arg3)

static ::ExceptionBaseExcNoSubscriber (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 61 of file timestep_control.h.

## ◆ map_value_type

 using Subscriptor::map_value_type = decltype(counter_map)::value_type
privateinherited

The data type used in counter_map.

Definition at line 230 of file subscriptor.h.

## ◆ map_iterator

 using Subscriptor::map_iterator = decltype(counter_map)::iterator
privateinherited

The iterator type used in counter_map.

Definition at line 235 of file subscriptor.h.

## ◆ 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 25 of file timestep_control.cc.

## ◆ declare_parameters()

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

Declare the control parameters for parameter handler.

Definition at line 51 of file timestep_control.cc.

## ◆ parse_parameters()

 void Algorithms::TimestepControl::parse_parameters ( 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 64 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 232 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 239 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 253 of file timestep_control.h.

## ◆ step()

 double Algorithms::TimestepControl::step ( ) const
inline

Return the size of the current time step.

Definition at line 246 of file timestep_control.h.

## ◆ now()

 double Algorithms::TimestepControl::now ( ) const
inline

Return the current time.

Definition at line 260 of file timestep_control.h.

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 77 of file timestep_control.cc.

## ◆ start() [2/2]

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

Set start value.

Definition at line 267 of file timestep_control.h.

## ◆ final() [2/2]

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

Set final time value.

Definition at line 274 of file timestep_control.h.

## ◆ tolerance() [2/2]

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

Set tolerance

Definition at line 281 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 288 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 295 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 302 of file timestep_control.h.

## ◆ print()

 bool Algorithms::TimestepControl::print ( )

Return true if this timestep should be written to disk.

Definition at line 102 of file timestep_control.cc.

## ◆ subscribe()

 void Subscriptor::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 136 of file subscriptor.cc.

## ◆ unsubscribe()

 void Subscriptor::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 156 of file subscriptor.cc.

## ◆ n_subscriptions()

 unsigned int Subscriptor::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 300 of file subscriptor.h.

## ◆ list_subscribers() [1/2]

template<typename StreamType >
 void Subscriptor::list_subscribers ( StreamType & stream ) const
inlineinherited

List the subscribers to the input stream.

Definition at line 317 of file subscriptor.h.

## ◆ list_subscribers() [2/2]

 void Subscriptor::list_subscribers ( ) const
inherited

List the subscribers to deallog.

Definition at line 204 of file subscriptor.cc.

## ◆ serialize()

template<class Archive >
 void Subscriptor::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 309 of file subscriptor.h.

## ◆ check_no_subscribers()

 void Subscriptor::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 subscriptor.cc.

## ◆ start_val

 double Algorithms::TimestepControl::start_val
private

The beginning of the time interval.

Definition at line 174 of file timestep_control.h.

## ◆ final_val

 double Algorithms::TimestepControl::final_val
private

The end of the time interval.

Definition at line 179 of file timestep_control.h.

## ◆ tolerance_val

 double Algorithms::TimestepControl::tolerance_val
private

The tolerance value controlling the time steps.

Definition at line 184 of file timestep_control.h.

## ◆ start_step_val

 double Algorithms::TimestepControl::start_step_val
private

The size of the first step.

Definition at line 189 of file timestep_control.h.

## ◆ max_step_val

 double Algorithms::TimestepControl::max_step_val
private

The maximum step size.

Definition at line 194 of file timestep_control.h.

## ◆ min_step_val

 double Algorithms::TimestepControl::min_step_val
private

The minimum step size.

Definition at line 199 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 205 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 211 of file timestep_control.h.

## ◆ now_val

 double Algorithms::TimestepControl::now_val
private

The current time.

Definition at line 216 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 222 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 227 of file timestep_control.h.

## ◆ counter

 std::atomic Subscriptor::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 219 of file subscriptor.h.

## ◆ counter_map

 std::map Subscriptor::counter_map
mutableprivateinherited

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

Definition at line 225 of file subscriptor.h.

## ◆ validity_pointers

 std::vector *> Subscriptor::validity_pointers
mutableprivateinherited

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

Definition at line 241 of file subscriptor.h.

## ◆ object_info

 const std::type_info* Subscriptor::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 249 of file subscriptor.h.

## ◆ mutex

 std::mutex Subscriptor::mutex
staticprivateinherited

A mutex used to ensure data consistency when printing out the list of subscribers.

Definition at line 271 of file subscriptor.h.

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