Dune::PDELab::InstationaryLocalOperatorDefaultMethods< R > Class Template Reference

Default class for additional methods in instationary local operators. More...

#include <dune/pdelab/localoperator/idefault.hh>

Public Member Functions
void	setTime (R t_)
	set time for subsequent evaluation More...
R	getTime () const
	get current time More...
void	preStep (RealType time, RealType dt, int stages)
	to be called once before each time step More...
void	postStep ()
	to be called once at the end of each time step More...
void	preStage (RealType time, int r)
	to be called once before each stage More...
int	getStage () const
	get current stage More...
void	postStage ()
	to be called once at the end of each stage
RealType	suggestTimestep (RealType dt) const
	to be called after stage 1 More...

Detailed Description

template<class R = double>
class Dune::PDELab::InstationaryLocalOperatorDefaultMethods< R >

Default class for additional methods in instationary local operators.

The algorithm used by the InstationaryGridOperator and the OneStepMethod to advance one step in time is as follows:

1. Call the method preStep(start_time_of_step, step_size, nstages) on each localoperator.
2. For each stage1 in [1, nstages]
   1. Call preStage(time_of_stage1, number_of_stage1) on each localoperator.
   2. Assemble constant part of residual: For each stage2 in [0, number_of_stage1-1]
      1. Call setTime(time_of_stage2) for each local operator.
      2. Iterate over grid and evaluate the local operator.
   3. Call setTime(time_of_stage1) for each local operator.
   4. Apply solver: Iterate over grid (possibly multiple times and evaluate local operator.
   5. Call postStage() on each local operator.
3. Call postStep() on the temporal local operator.

The algorithm used by the InstationaryGridOperator and the ExplicitOneStepMethod to advance one step in time is as follows:

1. Call the method preStep(start_time_of_step, step_size, nstages) on each localoperator.
2. For each stage1 in [1, nstages]
   1. Call preStage(time_of_stage1, number_of_stage1) on each localoperator.
   2. Assemble constant part of residual: For each stage2 in [0, number_of_stage1-1]
      1. Call setTime(time_of_stage2) for each local operator.
      2. Iterate over grid and evaluate the local operator.
   3. Call setTime(time_of_stage1) for each local operator.
   4. Assemble matrices to be solved: Iterate over the grid and evaluate the local operator.
   5. If stage1 == 1:
      1. Possibly call suggestTimeStep() and adjust the time step accordingly.
   6. Call postStage() on each local operator.
3. Call postStep() on the temporal local operator.

The algorithm used by the MultiStepGridOperator and the MultiStepMethod to advance one step in time is as follows:

1. Call the method preStep(start_time_of_step, step_size, 1) on each localoperator.
2. Call the method preStage(end_time_of_step, 1) on each local operator.
3. Assemble constant part of residual: For each step in [1, number_of_steps]
   1. Call setTime(end_time_of_step-step_size*number_of_step) for each local operator.
   2. Iterate over grid and evaluate the local operators.
4. Call setTime(end_time_of_step) for each local operator.
5. Apply solver: Iterate over grid (possibly multiple times and evaluate local operator.
6. Call postStage() on each local operator.
7. Call postStep() on each local operator.

Examples

recipe-operator-splitting.cc.

Member Function Documentation

getStage()

template<class R = double>

int Dune::PDELab::InstationaryLocalOperatorDefaultMethods< R >::getStage ( ) const

inline

get current stage

Returns

The current stage number previously set by preStage().

getTime()

template<class R = double>

R Dune::PDELab::InstationaryLocalOperatorDefaultMethods< R >::getTime ( ) const

inline

get current time

Returns

The time previously set by setTime().

postStep()

template<class R = double>

void Dune::PDELab::InstationaryLocalOperatorDefaultMethods< R >::postStep ( )

inline

to be called once at the end of each time step

Note

With the OneStepMethod and the ExplicitOneStepMetod, for reasons unknown this is only called for temporal but not for spatial local operators. With the MultiStepMethod this is called for all local operators.

preStage()

template<class R = double>

void Dune::PDELab::InstationaryLocalOperatorDefaultMethods< R >::preStage ( RealType  time, int  r  )

inline

to be called once before each stage

Parameters

time	Time of the stage
r	Number of the stage, r ∈ [1, nstages] inclusive, where nstages is the number of stage in the step given in the previous call to preStep()

Note

For ExplicitOneStepMethod the time given here for stage 1 may be incorrect, since the time step size is only finally determined after the first stage has been assembled.

For the MultiStepMethod, this is called once after preStep() with r=1.

preStep()

template<class R = double>

void Dune::PDELab::InstationaryLocalOperatorDefaultMethods< R >::preStep ( RealType  time, RealType  dt, int  stages  )

inline

to be called once before each time step

Parameters

time	Time at beginning of the step.
dt	Size of time step.
stages	Number of stages to do in the step. For the MultiStepMethod this is always 1.

Note

For ExplicitOneStepMethod the dt given here may be incorrect, since the time step size is only finally determined after the first stage has been assembled.

For the MultiStepMethod the number of stages is given as

1. Since there are no times of evaluation in the middle of the step, a multi-step method is similar to a one step method with one stage.

setTime()

template<class R = double>

void Dune::PDELab::InstationaryLocalOperatorDefaultMethods< R >::setTime ( R  t_ )

inline

set time for subsequent evaluation

This method set the time for subsequent calls to the alpha_*(), lambda_*(), jacobian_*() and jacobian_apply_*() methods.

Note

For ExplicitOneStepMethod the time given here in the first stage may be incorrect, since the time step size is only finally determined after the first stage has been assembled.

Referenced by Dune::PDELab::ConvectionDiffusionDG< T, FiniteElementMap >::setTime().

suggestTimestep()

template<class R = double>

RealType Dune::PDELab::InstationaryLocalOperatorDefaultMethods< R >::suggestTimestep ( RealType  dt ) const

inline

to be called after stage 1

Note

Only used by the ExplicitOneStepMethod.

This may be called on the spatial local operator in the case of an explicit one step scheme. It is called after stage 1 has been assembled (so the time given to preStep() may not apply anymore in this case). All the alpha_*() and lambda_*() methods should have been called, so they are a good place to generate the information returned here.

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

• dune/pdelab/localoperator/idefault.hh