Algorithms::TimestepControl Class Reference

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

Inheritance diagram for Algorithms::TimestepControl:

Public Types
enum	Strategy { uniform, doubling }

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
bool	advance ()
void	start (double)
void	final (double)
void	tolerance (double)
void	strategy (Strategy)
void	start_step (const double step)
void	max_step (double)
void	restart ()
bool	print ()
void	file_name_format (const char *)
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 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)

Private Attributes
double	current_step_val

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.

Definition at line 50 of file timestep_control.h.

Member Enumeration Documentation

Strategy

enum Algorithms::TimestepControl::Strategy

The time stepping strategies. These are controlled by the value of tolerance() and start_step().

Enumerator
uniform	Choose a uniform time step size. The step size is determined by start_step(), tolerance() is ignored.
doubling	Start with the time step size given by start_step() and double it in every step. tolerance() is ignored. This strategy is intended for pseudo-timestepping schemes computing a stationary limit.

Definition at line 57 of file timestep_control.h.

Constructor & Destructor Documentation

TimestepControl()

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 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 TimestepControl::parse_parameters

(

ParameterHandler &

param

)

Read the control parameters from a parameter handler.

Definition at line 66 of file timestep_control.cc.

start() [1/2]

double Algorithms::TimestepControl::start ( ) const

inline

The left end of the time interval.

Definition at line 192 of file timestep_control.h.

final() [1/2]

double Algorithms::TimestepControl::final ( ) const

inline

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

Definition at line 199 of file timestep_control.h.

tolerance() [1/2]

double Algorithms::TimestepControl::tolerance ( ) const

inline

The tolerance value controlling the time steps.

Definition at line 213 of file timestep_control.h.

step()

double Algorithms::TimestepControl::step ( ) const

inline

The size of the current time step.

Definition at line 206 of file timestep_control.h.

now()

double Algorithms::TimestepControl::now ( ) const

inline

The current time.

Definition at line 220 of file timestep_control.h.

advance()

bool 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 85 of file timestep_control.cc.

start() [2/2]

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

inline

Set start value.

Definition at line 227 of file timestep_control.h.

final() [2/2]

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

inline

Set final time value.

Definition at line 234 of file timestep_control.h.

tolerance() [2/2]

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

inline

Set tolerance

Definition at line 241 of file timestep_control.h.

strategy()

void Algorithms::TimestepControl::strategy ( Strategy  t )

inline

Set strategy.

Definition at line 248 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 255 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 262 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 269 of file timestep_control.h.

print()

bool TimestepControl::print

(

)

Return true if this timestep should be written to disk.

Definition at line 126 of file timestep_control.cc.

file_name_format()

void Algorithms::TimestepControl::file_name_format ( const char *  fmt )

inline

Set the output name template.

Definition at line 282 of file timestep_control.h.

Member Data Documentation

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 aimed at final_val.

Definition at line 180 of file timestep_control.h.

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

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