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Tempus::StepperForwardEuler< Scalar > Class Template Reference

Forward Euler time stepper. More...

#include <Tempus_StepperForwardEuler_decl.hpp>

Inheritance diagram for Tempus::StepperForwardEuler< Scalar >:
Tempus::StepperExplicit< Scalar > Tempus::Stepper< Scalar > Tempus_Test::PhysicsStateTest_StepperForwardEuler< Scalar >

Public Member Functions

 StepperForwardEuler ()
 Default constructor. More...
 
 StepperForwardEuler (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &appModel, Teuchos::RCP< Teuchos::ParameterList > pList=Teuchos::null)
 Constructor. More...
 
Basic stepper methods
virtual void setObserver (Teuchos::RCP< StepperObserver< Scalar > > obs=Teuchos::null)
 Set Observer. More...
 
virtual void initialize ()
 Initialize during construction and after changing input parameters. More...
 
virtual void setInitialConditions (const Teuchos::RCP< SolutionHistory< Scalar > > &solutionHistory)
 Set the initial conditions, make them consistent, and set needed memory. More...
 
virtual void takeStep (const Teuchos::RCP< SolutionHistory< Scalar > > &solutionHistory)
 Take the specified timestep, dt, and return true if successful. More...
 
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 OrderODE getOrderODE () 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
 
Overridden from Teuchos::Describable
virtual std::string description () const
 
virtual void describe (Teuchos::FancyOStream &out, const Teuchos::EVerbosityLevel verbLevel) const
 
- Public Member Functions inherited from Tempus::StepperExplicit< Scalar >
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 Scalar getInitTimeStep (const Teuchos::RCP< SolutionHistory< Scalar > > &) const
 
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 std::string getStepperType () const
 
virtual void setInitialGuess (Teuchos::RCP< const Thyra::VectorBase< Scalar > >)
 Pass initial guess to Newton solver (only relevant for implicit solvers) More...
 
virtual bool isExplicit () const
 
virtual bool isImplicit () const
 
virtual bool isExplicitImplicit () const
 
virtual bool isOneStepMethod () const
 
virtual bool isMultiStepMethod () const
 
virtual bool getEmbedded () const
 
virtual void setUseFSAL (bool a)
 
virtual bool getUseFSAL () const
 
virtual void setICConsistency (std::string s)
 
virtual std::string getICConsistency () const
 
virtual void setICConsistencyCheck (bool c)
 
virtual bool getICConsistencyCheck () const
 
virtual void setStepperX (Teuchos::RCP< Thyra::VectorBase< Scalar > > x)
 Set x for Stepper storage. More...
 
virtual void setStepperXDot (Teuchos::RCP< Thyra::VectorBase< Scalar > > xDot)
 Set xDot for Stepper storage. More...
 
virtual void setStepperXDotDot (Teuchos::RCP< Thyra::VectorBase< Scalar > > xDotDot)
 Set x for Stepper storage. More...
 
virtual Teuchos::RCP
< Thyra::VectorBase< Scalar > > 
getStepperX (Teuchos::RCP< SolutionState< Scalar > > state)
 Get x from SolutionState or Stepper storage. More...
 
virtual Teuchos::RCP
< Thyra::VectorBase< Scalar > > 
getStepperXDot (Teuchos::RCP< SolutionState< Scalar > > state)
 Get xDot from SolutionState or Stepper storage. More...
 
virtual Teuchos::RCP
< Thyra::VectorBase< Scalar > > 
getStepperXDotDot (Teuchos::RCP< SolutionState< Scalar > > state)
 Get xDotDot from SolutionState or Stepper storage. More...
 
virtual void evaluateExplicitODE (Teuchos::RCP< Thyra::VectorBase< Scalar > > xDot, Teuchos::RCP< const Thyra::VectorBase< Scalar > > x, const Scalar time)
 Evaluate xDot = f(x,t). More...
 
virtual void evaluateExplicitODE (Teuchos::RCP< Thyra::VectorBase< Scalar > > xDotDot, Teuchos::RCP< const Thyra::VectorBase< Scalar > > x, Teuchos::RCP< const Thyra::VectorBase< Scalar > > xDot, const Scalar time)
 Evaluate xDotDot = f(x, xDot, t). More...
 
- Public Member Functions inherited from Tempus::Stepper< Scalar >
virtual void modelWarning () const
 
void getValidParametersBasic (Teuchos::RCP< Teuchos::ParameterList > pl) const
 
virtual void createSubSteppers (std::vector< Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > >)
 
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
 

Protected Attributes

Teuchos::RCP
< StepperForwardEulerObserver
< Scalar > > 
stepperFEObserver_
 
- Protected Attributes inherited from Tempus::StepperExplicit< Scalar >
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< StepperObserver
< Scalar > > 
stepperObserver_
 
Teuchos::RCP
< Thyra::VectorBase< Scalar > > 
stepperX_
 
Teuchos::RCP
< Thyra::VectorBase< Scalar > > 
stepperXDot_
 
Teuchos::RCP
< Thyra::VectorBase< Scalar > > 
stepperXDotDot_
 

Detailed Description

template<class Scalar>
class Tempus::StepperForwardEuler< Scalar >

Forward Euler time stepper.

For the explicit ODE system,

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

the Forward Euler stepper can be written as

\[ x_{n} = x_{n-1} + \Delta t\, \bar{f}(x_{n-1},t_{n-1}) \]

Forward Euler is an explicit time stepper (i.e., no solver used). Note that the time derivative by definition is

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

Algorithm The single-timestep algorithm for Forward Euler is simply,

  • $\dot{x}_{n-1} \leftarrow \bar{f}(x_{n-1},t_{n-1})$
  • $x_{n} \leftarrow x_{n-1} + \Delta t\, \dot{x}_{n-1}$

Note that $x_n$ and $\dot{x}_{n-1}$ are not at the same time level at the end of the time step (i.e., they are not sync'ed).

To have them at the same time level, we can use the First-Step-As-Last (FSAL) principle where the function evaulation from the last time step can be used as the first function evalulation of the current step. For the Forward Euler, the FSAL algorithm is

  • $x_{n} \leftarrow x_{n-1} + \Delta t\, \dot{x}_{n-1}$
  • $\dot{x}_n \leftarrow \bar{f}(x_{n},t_{n})$

The default for Forward Euler is to use FSAL (useFSAL=true).

Definition at line 53 of file Tempus_StepperForwardEuler_decl.hpp.

Constructor & Destructor Documentation

template<class Scalar >
Tempus::StepperForwardEuler< Scalar >::StepperForwardEuler ( )

Default constructor.

Definition at line 19 of file Tempus_StepperForwardEuler_impl.hpp.

template<class Scalar >
Tempus::StepperForwardEuler< Scalar >::StepperForwardEuler ( const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &  appModel,
Teuchos::RCP< Teuchos::ParameterList >  pList = Teuchos::null 
)

Constructor.

Definition at line 26 of file Tempus_StepperForwardEuler_impl.hpp.

Member Function Documentation

template<class Scalar >
void Tempus::StepperForwardEuler< Scalar >::describe ( Teuchos::FancyOStream &  out,
const Teuchos::EVerbosityLevel  verbLevel 
) const
virtual

Definition at line 183 of file Tempus_StepperForwardEuler_impl.hpp.

template<class Scalar >
std::string Tempus::StepperForwardEuler< Scalar >::description ( ) const
virtual

Definition at line 175 of file Tempus_StepperForwardEuler_impl.hpp.

template<class Scalar >
Teuchos::RCP< Teuchos::ParameterList > Tempus::StepperForwardEuler< Scalar >::getDefaultParameters ( ) const
virtual

Implements Tempus::Stepper< Scalar >.

Definition at line 231 of file Tempus_StepperForwardEuler_impl.hpp.

template<class Scalar >
Teuchos::RCP< Tempus::StepperState< Scalar > > Tempus::StepperForwardEuler< Scalar >::getDefaultStepperState ( )
virtual

Get a default (initial) StepperState.

Provide a StepperState to the SolutionState. This Stepper does not have any special state data, so just provide the base class StepperState with the Stepper description. This can be checked to ensure that the input StepperState can be used by this Stepper.

Implements Tempus::Stepper< Scalar >.

Definition at line 166 of file Tempus_StepperForwardEuler_impl.hpp.

template<class Scalar >
Teuchos::RCP< Teuchos::ParameterList > Tempus::StepperForwardEuler< Scalar >::getNonconstParameterList ( )

Definition at line 246 of file Tempus_StepperForwardEuler_impl.hpp.

template<class Scalar >
virtual Scalar Tempus::StepperForwardEuler< Scalar >::getOrder ( ) const
inlinevirtual

Implements Tempus::Stepper< Scalar >.

Definition at line 89 of file Tempus_StepperForwardEuler_decl.hpp.

template<class Scalar >
virtual Scalar Tempus::StepperForwardEuler< Scalar >::getOrderMax ( ) const
inlinevirtual

Implements Tempus::Stepper< Scalar >.

Definition at line 91 of file Tempus_StepperForwardEuler_decl.hpp.

template<class Scalar >
virtual Scalar Tempus::StepperForwardEuler< Scalar >::getOrderMin ( ) const
inlinevirtual

Implements Tempus::Stepper< Scalar >.

Definition at line 90 of file Tempus_StepperForwardEuler_decl.hpp.

template<class Scalar >
virtual OrderODE Tempus::StepperForwardEuler< Scalar >::getOrderODE ( ) const
inlinevirtual

Implements Tempus::Stepper< Scalar >.

Definition at line 93 of file Tempus_StepperForwardEuler_decl.hpp.

template<class Scalar >
Teuchos::RCP< const Teuchos::ParameterList > Tempus::StepperForwardEuler< Scalar >::getValidParameters ( ) const

Definition at line 216 of file Tempus_StepperForwardEuler_impl.hpp.

template<class Scalar >
void Tempus::StepperForwardEuler< Scalar >::initialize ( )
virtual

Initialize during construction and after changing input parameters.

Implements Tempus::Stepper< Scalar >.

Definition at line 62 of file Tempus_StepperForwardEuler_impl.hpp.

template<class Scalar >
void Tempus::StepperForwardEuler< Scalar >::setInitialConditions ( const Teuchos::RCP< SolutionHistory< Scalar > > &  solutionHistory)
virtual

Set the initial conditions, make them consistent, and set needed memory.

Reimplemented from Tempus::StepperExplicit< Scalar >.

Definition at line 74 of file Tempus_StepperForwardEuler_impl.hpp.

template<class Scalar >
void Tempus::StepperForwardEuler< Scalar >::setObserver ( Teuchos::RCP< StepperObserver< Scalar > >  obs = Teuchos::null)
virtual

Set Observer.

Implements Tempus::Stepper< Scalar >.

Definition at line 42 of file Tempus_StepperForwardEuler_impl.hpp.

template<class Scalar >
void Tempus::StepperForwardEuler< Scalar >::setParameterList ( const Teuchos::RCP< Teuchos::ParameterList > &  pl)

Definition at line 193 of file Tempus_StepperForwardEuler_impl.hpp.

template<class Scalar >
void Tempus::StepperForwardEuler< Scalar >::takeStep ( const Teuchos::RCP< SolutionHistory< Scalar > > &  solutionHistory)
virtual

Take the specified timestep, dt, and return true if successful.

Implements Tempus::Stepper< Scalar >.

Definition at line 89 of file Tempus_StepperForwardEuler_impl.hpp.

template<class Scalar >
Teuchos::RCP< Teuchos::ParameterList > Tempus::StepperForwardEuler< Scalar >::unsetParameterList ( )

Definition at line 254 of file Tempus_StepperForwardEuler_impl.hpp.

Member Data Documentation

template<class Scalar >
Teuchos::RCP<StepperForwardEulerObserver<Scalar> > Tempus::StepperForwardEuler< Scalar >::stepperFEObserver_
protected

Definition at line 114 of file Tempus_StepperForwardEuler_decl.hpp.


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