Application class performing the theta timestepping scheme. More...

#include <timestepping.h>

Inheritance diagram for AppFrame::ThetaTimestepping:

Collaboration diagram for AppFrame::ThetaTimestepping:

Public Member Functions
	ThetaTimestepping (ApplicationBase &app)
	Constructor, receiving the application computing the residual in each timestep.

	ThetaTimestepping (ApplicationBase &app, const Residual &res)
	Constructor, receiving the application computing the residual in each timestep and a Residual integrator for computing the vector 1/dt + (1-theta) A.

virtual double	residual (FEVector &start, const FEVectors &rhs)
	Does nothing and avoids residual function of the base application being called.

virtual void	solve (FEVector &start, const FEVectors &rhs)
	The actual timestep solver.

virtual void	declare_parameters (ParameterHandler &param)
	Declare parameters for a parameter file.

virtual void	initialize (ParameterHandler &param)
	Pure virtual initialization function.

void	_initialize (ParameterHandler &param)
	Read the parameters.

Public Member Functions inherited from AppFrame::ApplicationCopy
	ApplicationCopy (ApplicationBase &ex_app)
	Constructor for a derived application.

	~ApplicationCopy ()

virtual void	remesh ()
	Generates the next mesh depending on the mesh generation parameters.

virtual void	init_vector (FEVector &dst) const
	Initialize vector to problem size.

virtual void	start_vector (FEVector &dst, std::string caller) const
	Initialize vector to problem size.

virtual void	Tsolve (FEVector &start, const FEVectors &rhs)
	Solve the dual system assembled with right hand side `rhs` and return the result in `start`.

virtual double	estimate (const FEVectors &src)
	Error estimation.

virtual double	evaluate (const FEVectors &src)
	Evaluate whatever the simulation was made for.

virtual void	grid_out (const std::string &filename) const
	Write the mesh in the format specified by the ParameterHandler.

virtual void	data_out (const std::string &filename, const FEVectors &src)
	Write data in the format specified by the ParameterHandler.

virtual std::string	id () const
	Return a unique identification string for this application.

virtual void	notify (const Event &reason)
	Add a reason for assembling.

Public Member Functions inherited from AppFrame::ApplicationBase
	ApplicationBase (boost::shared_ptr< ApplicationData > ex_data=boost::shared_ptr< ApplicationData >())
	Constructor for an application.

	ApplicationBase (const ApplicationBase &other)
	Copy constructor.

virtual	~ApplicationBase ()
	Virtual destructor.

void	print_parameters_to_file (ParameterHandler &param, const std::string &file_name, const ParameterHandler::OutputStyle &style)
	Print default parameters for the application to a file.

virtual double	residual (FEVector &dst, const FEVectors &src, bool apply_boundaries=true)
	Compute residual of `src` and store it into `dst`.

virtual void	data_out (const std::string &filename, const FEVectors &src, const std::vector< std::string >)

boost::shared_ptr < ApplicationData >	get_data ()
	Get access to the protected variable data.

const boost::shared_ptr < ApplicationData >	get_data () const
	Get read-only access to the protected variable data.

virtual void	clear ()
	Reset the application class such that a call to initialize() is possible again and will produce the same result as if the object was fresh.

void	clear_events ()
	Clear all notifications.

Static Public Attributes
static const Event	new_time
	ThetaTimestepping notifies of this Event if the next point in time is reached.

static const Event	new_step_size
	ThetaTimestepping notifies of this Event if the time step size has changed.

Protected Attributes
TimestepControl	control

Protected Attributes inherited from AppFrame::ApplicationCopy
SmartPointer< ApplicationBase >	app
	Pointer to the application this one depends upon.

Protected Attributes inherited from AppFrame::ApplicationBase
boost::shared_ptr < ApplicationData >	data
	Object for auxiliary data.

Event	notifications
	Accumulate reasons for reassembling here.

Private Attributes
double	theta
	The control parameter in the range `[0,1]`.

bool	adaptive
	Use adaptive theta if `true`.

ApplicationResidual	default_residual
	Default residual object if the function ApplicationBase::residual() shoud be used.

SmartPointer< const Residual >	compute_residual
	The Residual object.

Additional Inherited Members
Protected Member Functions inherited from AppFrame::ApplicationBase
void	print_caller_name (const std::string &caller_name) const
	Print caller name.

Detailed Description

Application class performing the theta timestepping scheme.

The theta scheme is an abstraction of implicit and explicit Euler schemes, the Crank-Nicholson scheme and linear combinations of those. The choice of the actual scheme is controlled by the parameter theta as follows.

theta=0: explicit Euler scheme
theta=1: implicit Euler scheme
theta=½: Crank-Nicholson scheme

For fixed theta, the Crank-Nicholson scheme is the only second order scheme. Nevertheless, further stability may be achieved by choosing theta larger than ½, thereby introducing a first order error term. In order to avoid a loss of convergence order, the adaptive theta scheme can be used, where theta=½+c dt.

The scheme sets the parameters theta time and timestep in ApplicationData. The residual is called with the solution at the previous time as first vector and should compute 1/dt + (1-theta) A. The function ApplicationBase::solve() is called with this result as first vector. It is then up to the underlying application to make sure that the right residual is computed.

A class that might help you implementing the right residuals is ThetaResidual. Refer to the examples Tests::RotatingCone1 and Tests::RotatingCone1 for the use of this class with linear and nonlinear operators.

Author: Guido Kanschat, 2006

Constructor & Destructor Documentation

AppFrame::ThetaTimestepping::ThetaTimestepping ( ApplicationBase & app )

Constructor, receiving the application computing the residual in each timestep.

AppFrame::ThetaTimestepping::ThetaTimestepping	(	ApplicationBase &	app,
		const Residual &	res
	)

Constructor, receiving the application computing the residual in each timestep and a Residual integrator for computing the vector 1/dt + (1-theta) A.

Member Function Documentation

void AppFrame::ThetaTimestepping::_initialize ( ParameterHandler & param )

Read the parameters.

virtual void AppFrame::ThetaTimestepping::declare_parameters ( ParameterHandler & param )

virtual

Declare parameters for a parameter file.

Pure virtual function MUST be redeclared in derived classes.

Reimplemented from AppFrame::ApplicationCopy.

virtual void AppFrame::ThetaTimestepping::initialize ( ParameterHandler & param )

virtual

Pure virtual initialization function.

Here, the parameters declared in the constructor are actually read from ParameterHandler.

This function must be overloaded in any derived class using its own values from the parameter file.

Initialization functions of derived classes must make sure to call all functions _initialize() of the base classes.

Reimplemented from AppFrame::ApplicationCopy.

virtual double AppFrame::ThetaTimestepping::residual	(	FEVector &	start,
		const FEVectors &	rhs
	)

virtual

Does nothing and avoids residual function of the base application being called.

Reimplemented from AppFrame::ApplicationCopy.

virtual void AppFrame::ThetaTimestepping::solve	(	FEVector &	start,
		const FEVectors &	rhs
	)

virtual

The actual timestep solver.

Reimplemented from AppFrame::ApplicationCopy.

Member Data Documentation

bool AppFrame::ThetaTimestepping::adaptive

private

Use adaptive theta if true.

SmartPointer<const Residual> AppFrame::ThetaTimestepping::compute_residual

private

The Residual object.

TimestepControl AppFrame::ThetaTimestepping::control

protected

ApplicationResidual AppFrame::ThetaTimestepping::default_residual

private

Default residual object if the function ApplicationBase::residual() shoud be used.

const Event AppFrame::ThetaTimestepping::new_step_size

static

ThetaTimestepping notifies of this Event if the time step size has changed.

const Event AppFrame::ThetaTimestepping::new_time

static

ThetaTimestepping notifies of this Event if the next point in time is reached.

double AppFrame::ThetaTimestepping::theta

private

The control parameter in the range [0,1].

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

timestepping.h

Public Member Functions

Static Public Attributes

Protected Attributes

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation