Explicit Runge-Kutta time stepper. More...

#include <Tempus_StepperExplicitRK_decl.hpp>

Inheritance diagram for Tempus::StepperExplicitRK< Scalar >:

Public Member Functions
	StepperExplicitRK (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &appModel, std::string stepperType="RK Explicit 4 Stage")
	Constructor to use default Stepper parameters. More...

	StepperExplicitRK (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &appModel, Teuchos::RCP< Teuchos::ParameterList > pList)
	Constructor to specialize Stepper parameters. More...

	StepperExplicitRK (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &appModel, std::string stepperType, Teuchos::RCP< Teuchos::ParameterList > pList)
	Constructor for StepperFactory. More...

Basic stepper methods
virtual void	setModel (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &appModel)

virtual void	setNonConstModel (const Teuchos::RCP< Thyra::ModelEvaluator< Scalar > > &appModel)

virtual Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > >	getModel ()

virtual void	setSolver (std::string solverName)
	Set solver via ParameterList solver name. More...

virtual void	setSolver (Teuchos::RCP< Teuchos::ParameterList > solverPL=Teuchos::null)
	Set solver via solver ParameterList. More...

virtual void	setSolver (Teuchos::RCP< Thyra::NonlinearSolverBase< Scalar > > solver)
	Set solver. More...

virtual Teuchos::RCP< Thyra::NonlinearSolverBase< Scalar > >	getSolver () const
	Get solver. More...

virtual void	setObserver (Teuchos::RCP< StepperObserver< Scalar > > obs=Teuchos::null)
	Set Observer. More...

virtual void	setTableau (std::string stepperType)

virtual void	setTableau (Teuchos::RCP< Teuchos::ParameterList > pList=Teuchos::null)

virtual void	initialize ()
	Initialize during construction and after changing input parameters. More...

virtual void	takeStep (const Teuchos::RCP< SolutionHistory< Scalar > > &solutionHistory)
	Take the specified timestep, dt, and return true if successful. More...

virtual void	setInitialGuess (Teuchos::RCP< const Thyra::VectorBase< Scalar > > initial_guess)
	Pass initial guess to Newton solver (only relevant for implicit solvers) More...

virtual std::string	getStepperType () const

virtual Teuchos::RCP< Tempus::StepperState< Scalar > >	getDefaultStepperState ()
	Get a default (initial) StepperState. More...

virtual Scalar	getOrder () const

virtual Scalar	getOrderMin () const

virtual Scalar	getOrderMax () const

virtual Scalar	getInitTimeStep (const Teuchos::RCP< SolutionHistory< Scalar > > &solutionHistory) const

virtual bool	isExplicit () const

virtual bool	isImplicit () const

virtual bool	isExplicitImplicit () const

virtual bool	isOneStepMethod () const

virtual bool	isMultiStepMethod () const

ParameterList methods
void	setParameterList (const Teuchos::RCP< Teuchos::ParameterList > &pl)

Teuchos::RCP< Teuchos::ParameterList >	getNonconstParameterList ()

Teuchos::RCP< Teuchos::ParameterList >	unsetParameterList ()

Teuchos::RCP< const Teuchos::ParameterList >	getValidParameters () const

Teuchos::RCP< Teuchos::ParameterList >	getDefaultParameters () const

Public Member Functions inherited from Tempus::Stepper< Scalar >
virtual void	createSubSteppers (std::vector< Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > > models)

void	validExplicitODE (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &model) const
	Validate that the model supports explicit ODE evaluation, f(x,t) [=xdot]. More...

void	validSecondOrderExplicitODE (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &model) const
	Validate that the model supports explicit second order ODE evaluation, f(x,xdot,t) [=xdotdot]. More...

void	validImplicitODE_DAE (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &model) const
	Validate ME supports implicit ODE/DAE evaluation, f(xdot,x,t) [= 0]. More...

void	validSecondOrderODE_DAE (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &model) const
	Validate ME supports 2nd order implicit ODE/DAE evaluation, f(xdotdot,xdot,x,t) [= 0]. More...

Teuchos::RCP< Teuchos::ParameterList >	defaultSolverParameters () const

Overridden from Teuchos::Describable
std::string	description_

Teuchos::RCP< Teuchos::ParameterList >	stepperPL_

Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > >	appModel_
	Explicit ODE ModelEvaluator. More...

Thyra::ModelEvaluatorBase::InArgs< Scalar >	inArgs_

Thyra::ModelEvaluatorBase::OutArgs< Scalar >	outArgs_

Teuchos::RCP< const RKButcherTableau< Scalar > >	ERK_ButcherTableau_

std::vector< Teuchos::RCP< Thyra::VectorBase< Scalar > > >	stageXDot_

Teuchos::RCP< Thyra::VectorBase< Scalar > >	stageX_

Teuchos::RCP< StepperObserver< Scalar > >	stepperObserver_

Teuchos::RCP< StepperExplicitRKObserver< Scalar > >	stepperExplicitRKObserver_

Teuchos::RCP< Thyra::VectorBase< Scalar > >	ee_

Teuchos::RCP< Thyra::VectorBase< Scalar > >	abs_u0

Teuchos::RCP< Thyra::VectorBase< Scalar > >	abs_u

Teuchos::RCP< Thyra::VectorBase< Scalar > >	sc

Teuchos::RCP< const Thyra::VectorBase< Scalar > >	initial_guess_

virtual std::string	description () const

virtual void	describe (Teuchos::FancyOStream &out, const Teuchos::EVerbosityLevel verbLevel) const

	StepperExplicitRK ()
	Default Constructor – not allowed. More...

Detailed Description

template<class Scalar>
class Tempus::StepperExplicitRK< Scalar >

Explicit Runge-Kutta time stepper.

For the explicit ODE system,

$\dot{x} = \bar{f}(x,t),$

the general explicit Runge-Kutta method for $s$ -stages can be written as

$X_{i} = x_{n-1} + \Delta t\,\sum_{j=1}^{i-1} a_{ij}\,\bar{f}(X_{j},t_{n-1}+c_{j}\Delta t)$

$x_{n} = x_{n-1} + \Delta t\,\sum_{i=1}^{s}b_{i}\,\bar{f}(X_{i},t_{n-1}+c_{i}\Delta t)$

where $X_{i}$ are intermediate approximations to the solution at times, $t_{n-1}+c_{i}\Delta t$ , (stage solutions) which may be correct to a lower order of accuracy than the solution, $x_{n}$ . We should note that these lower-order approximations are combined through $b_{i}$ so that error terms cancel out and produce a more accurate solution. Note for explicit RK that $a_{ij}=0$ for $j \leq i$ and does not require any solves. Note that the stage time derivatives are

$\dot{X}_{i} = \bar{f}(X_{i},t_{n-1}+c_{i}\Delta t),$

and the time derivative by definition is

$\dot{x}_{n} = \bar{f}(x_{n},t_{n}),$

Algorithm The single-timestep algorithm for Explicit RK is simply,

for do
- $X_i \leftarrow x_{n-1} + \Delta t\,\sum_{j=1}^{i-1} a_{ij}\,\dot{X}_j$
- Evaluate $\bar{f}(X_{i},t_{n-1}+c_{i}\Delta t)$
- $\dot{X}_i \leftarrow \bar{f}(X_i,t_{n-1}+c_i\Delta t)$
end for
$x_n \leftarrow x_{n-1} + \Delta t\,\sum_{i=1}^{s}b_i\,\dot{X}_i$
$\dot{x}_n \leftarrow \bar{f}(x_{n},t_{n})$ [Optional]

Definition at line 64 of file Tempus_StepperExplicitRK_decl.hpp.

Constructor & Destructor Documentation

◆ StepperExplicitRK() [1/4]

template<class Scalar >

Tempus::StepperExplicitRK< Scalar >::StepperExplicitRK	(	const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &	appModel,
		std::string	stepperType = `"RK Explicit 4 Stage"`
	)

Constructor to use default Stepper parameters.

Definition at line 21 of file Tempus_StepperExplicitRK_impl.hpp.

◆ StepperExplicitRK() [2/4]

template<class Scalar >

Tempus::StepperExplicitRK< Scalar >::StepperExplicitRK	(	const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &	appModel,
		Teuchos::RCP< Teuchos::ParameterList >	pList
	)

Constructor to specialize Stepper parameters.

Definition at line 31 of file Tempus_StepperExplicitRK_impl.hpp.

◆ StepperExplicitRK() [3/4]

template<class Scalar >

Tempus::StepperExplicitRK< Scalar >::StepperExplicitRK	(	const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &	appModel,
		std::string	stepperType,
		Teuchos::RCP< Teuchos::ParameterList >	pList
	)

Constructor for StepperFactory.

Definition at line 42 of file Tempus_StepperExplicitRK_impl.hpp.

◆ StepperExplicitRK() [4/4]

template<class Scalar>

Tempus::StepperExplicitRK< Scalar >::StepperExplicitRK ( )

private

Default Constructor – not allowed.

Member Function Documentation

◆ describe()

template<class Scalar >

void Tempus::StepperExplicitRK< Scalar >::describe	(	Teuchos::FancyOStream &	out,
		const Teuchos::EVerbosityLevel	verbLevel
	)		const

virtual

Definition at line 417 of file Tempus_StepperExplicitRK_impl.hpp.

◆ description()

template<class Scalar >

std::string Tempus::StepperExplicitRK< Scalar >::description ( ) const

virtual

Definition at line 410 of file Tempus_StepperExplicitRK_impl.hpp.

◆ getDefaultParameters()

template<class Scalar >

Teuchos::RCP< Teuchos::ParameterList > Tempus::StepperExplicitRK< Scalar >::getDefaultParameters ( ) const

virtual

Public Member Functions

Overridden from Teuchos::Describable

Detailed Description

template<class Scalar> class Tempus::StepperExplicitRK< Scalar >

Constructor & Destructor Documentation

◆ StepperExplicitRK() [1/4]

◆ StepperExplicitRK() [2/4]

◆ StepperExplicitRK() [3/4]

◆ StepperExplicitRK() [4/4]

Member Function Documentation

◆ describe()

◆ description()

◆ getDefaultParameters()

◆ getDefaultStepperState()

◆ getInitTimeStep()

◆ getModel()

◆ getNonconstParameterList()

◆ getOrder()

◆ getOrderMax()

◆ getOrderMin()

◆ getSolver()

◆ getStepperType()

◆ getValidParameters()

◆ initialize()

◆ isExplicit()

◆ isExplicitImplicit()

◆ isImplicit()

◆ isMultiStepMethod()

◆ isOneStepMethod()

◆ setInitialGuess()

◆ setModel()

◆ setNonConstModel()

◆ setObserver()

◆ setParameterList()

◆ setSolver() [1/3]

◆ setSolver() [2/3]

◆ setSolver() [3/3]

◆ setTableau() [1/2]

◆ setTableau() [2/2]

◆ takeStep()

◆ unsetParameterList()

Member Data Documentation

◆ abs_u

◆ abs_u0

◆ appModel_

◆ description_

◆ ee_

◆ ERK_ButcherTableau_

◆ inArgs_

◆ initial_guess_

◆ outArgs_

◆ sc

◆ stageX_

◆ stageXDot_

◆ stepperExplicitRKObserver_

◆ stepperObserver_

◆ stepperPL_

template<class Scalar>
class Tempus::StepperExplicitRK< Scalar >