Reference documentation for deal.II version 9.1.1
Algorithms::TimestepControl Class Reference

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

Inheritance diagram for Algorithms::TimestepControl:
[legend]

## 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

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 ()

Subscriptoroperator= (const Subscriptor &)

Subscriptoroperator= (Subscriptor &&) noexcept

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

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 ::ExceptionBaseExcInUse (int arg1, std::string arg2, std::string arg3)

static ::ExceptionBaseExcNoSubscriber (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 52 of file timestep_control.h.

## ◆ 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 59 of file timestep_control.h.

## ◆ 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 25 of file timestep_control.cc.

## ◆ declare_parameters()

 void TimestepControl::declare_parameters ( ParameterHandler & param )
static

Declare the control parameters for parameter handler.

Definition at line 53 of file timestep_control.cc.

## ◆ parse_parameters()

 void TimestepControl::parse_parameters ( ParameterHandler & param )

Read the control parameters from a parameter handler.

Definition at line 69 of file timestep_control.cc.

## ◆ start() [1/2]

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

The left end of the time interval.

Definition at line 211 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 218 of file timestep_control.h.

## ◆ tolerance() [1/2]

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

The tolerance value controlling the time steps.

Definition at line 232 of file timestep_control.h.

## ◆ step()

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

The size of the current time step.

Definition at line 225 of file timestep_control.h.

## ◆ now()

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

The current time.

Definition at line 239 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 87 of file timestep_control.cc.

## ◆ start() [2/2]

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

Set start value.

Definition at line 246 of file timestep_control.h.

## ◆ final() [2/2]

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

Set final time value.

Definition at line 253 of file timestep_control.h.

## ◆ tolerance() [2/2]

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

Set tolerance

Definition at line 260 of file timestep_control.h.

## ◆ strategy()

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

Set strategy.

Definition at line 267 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 274 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 281 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 288 of file timestep_control.h.

## ◆ print()

 bool TimestepControl::print ( )

Return true if this timestep should be written to disk.

Definition at line 129 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 301 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 aimed at final_val.

Definition at line 199 of file timestep_control.h.

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