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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 > Teuchos::Describable Teuchos::VerboseObject< Stepper< Scalar > > Teuchos::LabeledObject Teuchos::VerboseObjectBase

Public Member Functions

 StepperForwardEuler ()
 Default constructor. More...
 
 StepperForwardEuler (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &appModel, bool useFSAL, std::string ICConsistency, bool ICConsistencyCheck, const Teuchos::RCP< StepperForwardEulerAppAction< Scalar > > &stepperFEAppAction)
 Constructor. More...
 
virtual void setAppAction (Teuchos::RCP< StepperForwardEulerAppAction< Scalar > > appAction)
 
virtual Teuchos::RCP
< StepperForwardEulerAppAction
< Scalar > > 
getAppAction () const
 
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 void setUseFSAL (bool a)
 
virtual OrderODE getOrderODE () const
 
virtual bool isValidSetup (Teuchos::FancyOStream &out) const
 
- Public Member Functions inherited from Tempus::StepperExplicit< Scalar >
void setStepperExplicitValues (Teuchos::RCP< Teuchos::ParameterList > pl)
 Set StepperExplicit member data from the ParameterList. More...
 
virtual void setModel (const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &appModel)
 Set model. More...
 
virtual Teuchos::RCP< const
Thyra::ModelEvaluator< Scalar > > 
getModel () const
 Return the application ModelEvaluator. More...
 
virtual Scalar getInitTimeStep (const Teuchos::RCP< SolutionHistory< Scalar > > &) const
 
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 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 void evaluateExplicitODE (Teuchos::RCP< Thyra::VectorBase< Scalar > > xDot, Teuchos::RCP< const Thyra::VectorBase< Scalar > > x, const Scalar time, const Teuchos::RCP< ExplicitODEParameters< Scalar > > &p)
 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, const Teuchos::RCP< ExplicitODEParameters< Scalar > > &p)
 Evaluate xDotDot = f(x, xDot, t). More...
 
- Public Member Functions inherited from Tempus::Stepper< Scalar >
void setStepperValues (const Teuchos::RCP< Teuchos::ParameterList > pl)
 Set Stepper member data from ParameterList. More...
 
virtual Teuchos::RCP< const
Teuchos::ParameterList
getValidParameters () const
 
Teuchos::RCP
< Teuchos::ParameterList
getValidParametersBasic () const
 Add basic parameters to Steppers ParameterList. More...
 
virtual void initialize ()
 Initialize after construction and changing input parameters. More...
 
virtual bool isInitialized ()
 True if stepper's member data is initialized. More...
 
virtual void checkInitialized ()
 Check initialization, and error out on failure. More...
 
void setStepperName (std::string s)
 Set the stepper name. More...
 
std::string getStepperName () const
 Get the stepper name. More...
 
std::string getStepperType () const
 Get the stepper type. The stepper type is used as an identifier for the stepper, and can only be set by the derived Stepper class. More...
 
void setUseFSALTrueOnly (bool a)
 
void setUseFSALFalseOnly (bool a)
 
bool getUseFSAL () const
 
void setICConsistency (std::string s)
 
std::string getICConsistency () const
 
void setICConsistencyCheck (bool c)
 
bool getICConsistencyCheck () const
 
virtual Teuchos::RCP
< Thyra::VectorBase< Scalar > > 
getStepperX ()
 Get Stepper x. More...
 
virtual Teuchos::RCP
< Thyra::VectorBase< Scalar > > 
getStepperXDot ()
 Get Stepper xDot. More...
 
virtual Teuchos::RCP
< Thyra::VectorBase< Scalar > > 
getStepperXDotDot ()
 Get Stepper xDotDot. More...
 
virtual Teuchos::RCP
< Thyra::VectorBase< Scalar > > 
getStepperXDotDot (Teuchos::RCP< SolutionState< Scalar > > state)
 Get xDotDot from SolutionState or Stepper storage. More...
 
virtual std::string description () const
 
- Public Member Functions inherited from Teuchos::Describable
void describe (std::ostream &out, const EVerbosityLevel verbLevel=verbLevel_default) const
 
virtual ~Describable ()
 
 LabeledObject ()
 
virtual ~LabeledObject ()
 
virtual void setObjectLabel (const std::string &objectLabel)
 
virtual std::string getObjectLabel () const
 
DescribableStreamManipulatorState describe (const Describable &describable, const EVerbosityLevel verbLevel=Describable::verbLevel_default)
 
std::ostream & operator<< (std::ostream &os, const DescribableStreamManipulatorState &d)
 
- Public Member Functions inherited from Teuchos::VerboseObject< Stepper< Scalar > >
 VerboseObject (const EVerbosityLevel verbLevel=VERB_DEFAULT, const RCP< FancyOStream > &oStream=Teuchos::null)
 
virtual const VerboseObjectsetVerbLevel (const EVerbosityLevel verbLevel) const
 
virtual const VerboseObjectsetOverridingVerbLevel (const EVerbosityLevel verbLevel) const
 
virtual EVerbosityLevel getVerbLevel () const
 
TEUCHOSPARAMETERLIST_LIB_DLL_EXPORT
RCP< const ParameterList
getValidVerboseObjectSublist ()
 
TEUCHOSPARAMETERLIST_LIB_DLL_EXPORT
void 
setupVerboseObjectSublist (ParameterList *paramList)
 
TEUCHOSPARAMETERLIST_LIB_DLL_EXPORT
void 
readVerboseObjectSublist (ParameterList *paramList, RCP< FancyOStream > *oStream, EVerbosityLevel *verbLevel)
 
void readVerboseObjectSublist (ParameterList *paramList, VerboseObject< ObjectType > *verboseObject)
 
- Public Member Functions inherited from Teuchos::VerboseObjectBase
virtual ~VerboseObjectBase ()
 
 VerboseObjectBase (const RCP< FancyOStream > &oStream=Teuchos::null)
 
virtual const VerboseObjectBasesetOStream (const RCP< FancyOStream > &oStream) const
 
virtual const VerboseObjectBasesetOverridingOStream (const RCP< FancyOStream > &oStream) const
 
virtual VerboseObjectBasesetLinePrefix (const std::string &linePrefix)
 
virtual RCP< FancyOStreamgetOStream () const
 
virtual RCP< FancyOStreamgetOverridingOStream () const
 
virtual std::string getLinePrefix () const
 
virtual OSTab getOSTab (const int tabs=1, const std::string &linePrefix="") const
 

Protected Attributes

Teuchos::RCP
< StepperForwardEulerAppAction
< Scalar > > 
stepperFEAppAction_
 
- Protected Attributes inherited from Tempus::StepperExplicit< Scalar >
Teuchos::RCP< const
Thyra::ModelEvaluator< Scalar > > 
appModel_
 Explicit ODE ModelEvaluator. More...
 
Thyra::ModelEvaluatorBase::InArgs
< Scalar > 
inArgs_
 
Thyra::ModelEvaluatorBase::OutArgs
< Scalar > 
outArgs_
 
- Protected Attributes inherited from Tempus::Stepper< Scalar >
bool useFSAL_ = false
 Use First-Same-As-Last (FSAL) principle. More...
 
bool isInitialized_
 True if stepper's member data is initialized. More...
 

Overridden from Teuchos::Describable

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

Additional Inherited Members

- Static Public Member Functions inherited from Teuchos::VerboseObject< Stepper< Scalar > >
static void setDefaultVerbLevel (const EVerbosityLevel defaultVerbLevel)
 
static EVerbosityLevel getDefaultVerbLevel ()
 
- Static Public Member Functions inherited from Teuchos::VerboseObjectBase
static void setDefaultOStream (const RCP< FancyOStream > &defaultOStream)
 
static RCP< FancyOStreamgetDefaultOStream ()
 
- Static Public Attributes inherited from Teuchos::Describable
static const EVerbosityLevel verbLevel_default
 
- Protected Member Functions inherited from Tempus::Stepper< Scalar >
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...
 
void setStepperType (std::string s)
 Set the stepper type. More...
 
- Protected Member Functions inherited from Teuchos::VerboseObject< Stepper< Scalar > >
void initializeVerboseObject (const EVerbosityLevel verbLevel=VERB_DEFAULT, const RCP< FancyOStream > &oStream=Teuchos::null)
 
- Protected Member Functions inherited from Teuchos::VerboseObjectBase
void initializeVerboseObjectBase (const RCP< FancyOStream > &oStream=Teuchos::null)
 
virtual void informUpdatedVerbosityState () const
 

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

\begin{center} \parbox{5in}{ \rule{5in}{0.4pt} \\ {\bf Algorithm} Forward Euler \\ \rule{5in}{0.4pt} \vspace{-15pt} \begin{enumerate} \setlength{\itemsep}{0pt} \setlength{\parskip}{0pt} \setlength{\parsep}{0pt} \item {\it appAction.execute(solutionHistory, stepper, BEGIN\_STEP)} \item {\bf if (Not ``Use FSAL'' or (previous step failed)) then} \item \quad {\it appAction.execute(solutionHistory, stepper, BEFORE\_EXPLICIT\_EVAL)} \item \quad $\dot{x}_{n-1} \leftarrow \bar{f}(x_{n-1},t_{n-1})$ \item {\bf endif} \item $x_{n} \leftarrow x_{n-1} + \Delta t\, \dot{x}_{n-1}$ \hfill {\it * Forward Euler update.} \item {\it appAction.execute(solutionHistory, stepper, END\_STEP)} \item {\bf if (``Use FSAL'') then} \item \quad {\it appAction.execute(solutionHistory, stepper, BEFORE\_EXPLICIT\_EVAL)} \item \quad $\dot{x}_n \leftarrow \bar{f}(x_{n},t_{n})$ \item {\bf endif} \item {\it appAction.execute(solutionHistory, stepper, END\_STEP)} \end{enumerate} \vspace{-10pt} \rule{5in}{0.4pt} } \end{center}

Note that with useFSAL=false $x_n$ 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-Same-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.

The default for Forward Euler is to use FSAL (useFSAL=true), but will also work with useFSAL=false. Using useFSAL=true does assume that the solution, $x$, and its time derivative, $\dot{x}$, are consistent at the initial conditions (ICs), i.e., $\dot{x}_{0} = \bar{f}(x_{0},t_{0})$. This can be ensured by setting setICConsistency("Consistent"), and checked with setICConsistencyCheck(true).

Definition at line 77 of file Tempus_StepperForwardEuler_decl.hpp.

Constructor & Destructor Documentation

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

Default constructor.

Definition at line 20 of file Tempus_StepperForwardEuler_impl.hpp.

template<class Scalar >
Tempus::StepperForwardEuler< Scalar >::StepperForwardEuler ( const Teuchos::RCP< const Thyra::ModelEvaluator< Scalar > > &  appModel,
bool  useFSAL,
std::string  ICConsistency,
bool  ICConsistencyCheck,
const Teuchos::RCP< StepperForwardEulerAppAction< Scalar > > &  stepperFEAppAction 
)

Constructor.

Definition at line 31 of file Tempus_StepperForwardEuler_impl.hpp.

Member Function Documentation

template<class Scalar >
void Tempus::StepperForwardEuler< Scalar >::setAppAction ( Teuchos::RCP< StepperForwardEulerAppAction< Scalar > >  appAction)
virtual

Definition at line 51 of file Tempus_StepperForwardEuler_impl.hpp.

template<class Scalar >
virtual Teuchos::RCP<StepperForwardEulerAppAction<Scalar> > Tempus::StepperForwardEuler< Scalar >::getAppAction ( ) const
inlinevirtual

Definition at line 96 of file Tempus_StepperForwardEuler_decl.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 65 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 82 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 180 of file Tempus_StepperForwardEuler_impl.hpp.

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

Implements Tempus::Stepper< Scalar >.

Definition at line 112 of file Tempus_StepperForwardEuler_decl.hpp.

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

Implements Tempus::Stepper< Scalar >.

Definition at line 113 of file Tempus_StepperForwardEuler_decl.hpp.

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

Implements Tempus::Stepper< Scalar >.

Definition at line 114 of file Tempus_StepperForwardEuler_decl.hpp.

template<class Scalar >
virtual void Tempus::StepperForwardEuler< Scalar >::setUseFSAL ( bool  a)
inlinevirtual

Reimplemented from Tempus::Stepper< Scalar >.

Definition at line 115 of file Tempus_StepperForwardEuler_decl.hpp.

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

Implements Tempus::Stepper< Scalar >.

Definition at line 120 of file Tempus_StepperForwardEuler_decl.hpp.

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

Reimplemented from Tempus::StepperExplicit< Scalar >.

Definition at line 188 of file Tempus_StepperForwardEuler_impl.hpp.

template<class Scalar >
bool Tempus::StepperForwardEuler< Scalar >::isValidSetup ( Teuchos::FancyOStream out) const
virtual

Reimplemented from Tempus::StepperExplicit< Scalar >.

Definition at line 203 of file Tempus_StepperForwardEuler_impl.hpp.

Member Data Documentation

template<class Scalar >
Teuchos::RCP<StepperForwardEulerAppAction<Scalar> > Tempus::StepperForwardEuler< Scalar >::stepperFEAppAction_
protected

Definition at line 132 of file Tempus_StepperForwardEuler_decl.hpp.


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