Semi-implicit IMEX sweeper. More...

#include <imex_sweeper.hpp>

Inheritance diagram for pfasst::encap::IMEXSweeper< time >:

Collaboration diagram for pfasst::encap::IMEXSweeper< time >:

Public Member Functions

	IMEXSweeper ()=default

virtual	~IMEXSweeper ()=default


virtual void	setup (bool coarse) override
	Setup (allocate etc) the sweeper. More...

virtual void	predict (bool initial) override
	Compute low-order provisional solution. More...

virtual void	sweep () override
	Perform one SDC sweep/iteration. More...

virtual void	advance () override
	Advance the end solution to start solution. More...

virtual void	reevaluate (bool initial_only) override
	Re-evaluate function values. More...

virtual void	integrate (time dt, vector< shared_ptr< Encapsulation< time >>> dst) const override
	Integrates values of right hand side at all time nodes \( t \in [0,M-1] \) simultaneously. More...

virtual void	residual (time dt, vector< shared_ptr< Encapsulation< time >>> dst) const override
	Compute residual at each SDC node (including FAS corrections). More...


virtual void	f_expl_eval (shared_ptr< Encapsulation< time >> f_expl_encap, shared_ptr< Encapsulation< time >> u_encap, time t)
	Evaluate the explicit part of the ODE. More...

virtual void	f_impl_eval (shared_ptr< Encapsulation< time >> f_impl_encap, shared_ptr< Encapsulation< time >> u_encap, time t)
	Evaluate the implicit part of the ODE. More...

virtual void	impl_solve (shared_ptr< Encapsulation< time >> f_encap, shared_ptr< Encapsulation< time >> u_encap, time t, time dt, shared_ptr< Encapsulation< time >> rhs_encap)
	Solve \( U - \Delta t F_{\rm impl}(U) = RHS \) for \( U \). More...

Public Member Functions inherited from pfasst::encap::EncapSweeper< time >
	EncapSweeper ()

virtual shared_ptr< Encapsulation< time > >	get_state (size_t m) const
	Retrieve solution values of current iteration at time node index `m`. More...

virtual shared_ptr< Encapsulation< time > >	get_tau (size_t m) const
	Retrieve FAS correction of current iteration at time node index `m`. More...

virtual shared_ptr< Encapsulation< time > >	get_saved_state (size_t m) const
	Retrieve solution values of previous iteration at time node index `m`. More...

virtual void	set_options () override
	Set options from command line etc. More...

virtual void	spread () override
	Initialize solution values at all time nodes with meaningful values. More...

virtual void	save (bool initial_only) override
	Save states (and/or function values) at all nodes. More...

virtual void	set_quadrature (shared_ptr< IQuadrature< time >> quadrature)

virtual shared_ptr< const IQuadrature< time > >	get_quadrature () const

virtual const vector< time >	get_nodes () const

virtual void	set_factory (shared_ptr< EncapFactory< time >> factory)

virtual shared_ptr< EncapFactory< time > >	get_factory () const

virtual shared_ptr< Encapsulation< time > >	get_start_state () const

virtual shared_ptr< Encapsulation< time > >	get_end_state ()

void	set_residual_tolerances (time abs_residual_tol, time rel_residual_tol, int order=0)
	Set residual tolerances for convergence checking. More...

virtual bool	converged () override
	Return convergence status. More...

virtual void	post (ICommunicator *comm, int tag) override

virtual void	send (ICommunicator *comm, int tag, bool blocking) override

virtual void	recv (ICommunicator *comm, int tag, bool blocking) override

virtual void	broadcast (ICommunicator *comm) override

Public Member Functions inherited from pfasst::ISweeper< time >
	ISweeper ()

virtual	~ISweeper ()

virtual void	set_controller (Controller< time > *ctrl)
	Set the sweepers controller. More...

virtual Controller< time > *	get_controller ()
	Accessor to the controller managing this sweeper. More...

virtual void	post_sweep ()
	Hook automatically run after each completed sweep. More...

virtual void	post_predict ()
	Hook automatically run after each completed predict. More...

virtual void	post_step ()
	Hook automatically run after each completed time step. More...

Protected Member Functions
virtual void	integrate_end_state (time dt)
	Set end state to \( U_0 + \int F_{expl} + F_{expl} \). More...

Protected Attributes

vector< shared_ptr< Encapsulation< time > > >	s_integrals
	Node-to-node integrals of \( F(t,u) \) at all time nodes of the current iteration. More...

vector< shared_ptr< Encapsulation< time > > >	fs_expl
	Values of the explicit part of the right hand side \( F_{expl}(t,u) \) at all time nodes of the current iteration. More...

shared_ptr< Encapsulation< time > >	fs_expl_start

vector< shared_ptr< Encapsulation< time > > >	fs_impl
	Values of the implicit part of the right hand side \( F_{impl}(t,u) \) at all time nodes of the current iteration. More...

Protected Attributes inherited from pfasst::encap::EncapSweeper< time >
string	FORMAT_STR

shared_ptr< IQuadrature< time > >	quadrature

shared_ptr< EncapFactory< time > >	factory
	Encapsulation data structure factory. More...

shared_ptr< Encapsulation< time > >	start_state
	Separate start state, i.e. initial condition for the sweeper's current time step. More...

shared_ptr< Encapsulation< time > >	end_state
	Current solution at \( T_{end} \). More...

vector< shared_ptr< Encapsulation< time > > >	residuals
	Place for the residuals at the different time nodes. More...

vector< shared_ptr< Encapsulation< time > > >	state
	Solution values \( U \) at all time nodes of the current iteration. More...

vector< shared_ptr< Encapsulation< time > > >	saved_state
	Solution values \( U \) at all time nodes of the previous iteration. More...

vector< shared_ptr< Encapsulation< time > > >	fas_corrections
	FAS corrections \( \tau \) at all time nodes of the current iteration. More...

int	residual_norm_order

time	abs_residual_tol
	Tolerance for absolute residual. More...

time	rel_residual_tol
	Tolerance for relative residual. More...

Protected Attributes inherited from pfasst::ISweeper< time >
Controller< time > *	controller
	Backreference to the controller managing the sweeper instance. More...

Private Member Functions
virtual void	predict_with_left (bool initial)

virtual void	predict_without_left (bool initial)

virtual void	sweep_with_left ()

virtual void	sweep_without_left ()

Detailed Description

template<typename time = time_precision>
class pfasst::encap::IMEXSweeper< time >

Semi-implicit IMEX sweeper.

This IMEX sweeper is for ODEs of the form \( \dot{U} = F_{\rm expl}(t,U) + F_{\rm impl}(t, U) \). To reduce complexity and computational effort the non-stiff part is treated explicitly and the stiff part implicitly.

This sweeper requires three interfaces to be implemented: two routines to evaluate the explicit \( F_{\rm expl} \) and implicit \( F_{\rm impl} \) pieces for a given state, and one routine that solves (perhaps with an external solver) the backward-Euler equation \( U^{n+1} - \Delta t F_{\rm impl}(U^{n+1}) = RHS \) for \( U^{n+1} \).

Template Parameters

time	precision type of the time dimension

Definition at line 34 of file imex_sweeper.hpp.

Constructor & Destructor Documentation

template<typename time = time_precision>

pfasst::encap::IMEXSweeper< time >::IMEXSweeper ( )

default

template<typename time = time_precision>

virtual pfasst::encap::IMEXSweeper< time >::~IMEXSweeper ( )

virtualdefault

Member Function Documentation

template<typename time >

void pfasst::encap::IMEXSweeper< time >::advance ( )

overridevirtual

Advance the end solution to start solution.

Reimplemented from pfasst::encap::EncapSweeper< time >.

Definition at line 87 of file imex_sweeper_impl.hpp.

template<typename time >

void pfasst::encap::IMEXSweeper< time >::f_expl_eval	(	shared_ptr< Encapsulation< time >>	f_expl_encap,
		shared_ptr< Encapsulation< time >>	u_encap,
		time	t
	)

virtual

Evaluate the explicit part of the ODE.

Parameters

[in,out]	f_expl_encap	Encapsulation to store the explicit function evaluation.
[in]	u_encap	Encapsulation that stores the solution state at which to evaluate the explicit part of the ODE.
[in]	t	Time point of the evaluation.

Note: This method must be implemented in derived sweepers.

Reimplemented in pfasst::examples::advection_diffusion::AdvectionDiffusionSweeper< time >.

Definition at line 146 of file imex_sweeper_impl.hpp.

References UNUSED.

template<typename time >

void pfasst::encap::IMEXSweeper< time >::f_impl_eval	(	shared_ptr< Encapsulation< time >>	f_impl_encap,
		shared_ptr< Encapsulation< time >>	u_encap,
		time	t
	)

virtual

Evaluate the implicit part of the ODE.

This is typically called to compute the implicit part of the right hand side at the first collocation node, and on all nodes after restriction or interpolation.

Parameters

[in,out]	f_impl_encap	Encapsulation to store the implicit function evaluation.
[in]	u_encap	Encapsulation storing the solution state at which to evaluate the implicit part of the ODE.
[in]	t	Time point of the evaluation.

Note: This method must be implemented in derived sweepers.

Reimplemented in pfasst::examples::advection_diffusion::AdvectionDiffusionSweeper< time >.

Definition at line 155 of file imex_sweeper_impl.hpp.

References UNUSED.

template<typename time >

void pfasst::encap::IMEXSweeper< time >::impl_solve	(	shared_ptr< Encapsulation< time >>	f_encap,
		shared_ptr< Encapsulation< time >>	u_encap,
		time	t,
		time	dt,
		shared_ptr< Encapsulation< time >>	rhs_encap
	)

virtual

Solve \( U - \Delta t F_{\rm impl}(U) = RHS \) for \( U \).

During an IMEX SDC sweep, the correction equation is evolved using a forward-Euler stepper for the explicit piece, and a backward-Euler stepper for the implicit piece. This routine (implemented by the user) performs the solve required to perform one backward-Euler sub-step, and also returns \( F_{\rm impl}(U) \).

Parameters

[in,out]	f_encap	Encapsulation to store the evaluated implicit piece.
[in,out]	u_encap	Encapsulation to store the solution of the backward-Euler sub-step.
[in]	t	time point (of \( RHS \)).
[in]	dt	sub-step size to the previous time point (\( \Delta t \)).
[in]	rhs_encap	Encapsulation that stores \( RHS \).

Note: This method must be implemented in derived sweepers.

Reimplemented in pfasst::examples::advection_diffusion::AdvectionDiffusionSweeper< time >.

Definition at line 164 of file imex_sweeper_impl.hpp.

References UNUSED.

template<typename time >

void pfasst::encap::IMEXSweeper< time >::integrate	(	time	dt,
		vector< shared_ptr< Encapsulation< time >>>	dst
	)		const

overridevirtual

Integrates values of right hand side at all time nodes \( t \in [0,M-1] \) simultaneously.

Parameters

[in]	dt	width of time interval to integrate over
[in,out]	dst	integrated values; will get zeroed out beforehand

Reimplemented from pfasst::encap::EncapSweeper< time >.

Definition at line 119 of file imex_sweeper_impl.hpp.

template<typename time >

void pfasst::encap::IMEXSweeper< time >::integrate_end_state ( time dt )

protectedvirtual

Set end state to \( U_0 + \int F_{expl} + F_{expl} \).

Definition at line 16 of file imex_sweeper_impl.hpp.

template<typename time >

void pfasst::encap::IMEXSweeper< time >::predict ( bool initial )

overridevirtual

Compute low-order provisional solution.

This performs forward/backward Euler steps across the nodes to compute a low-order provisional solution.

Parameters

[in] initial if true the explicit and implicit part of the right hand side of the ODE get evaluated with the initial value

Implements pfasst::ISweeper< time >.

Definition at line 55 of file imex_sweeper_impl.hpp.

template<typename time >

void pfasst::encap::IMEXSweeper< time >::predict_with_left ( bool initial )

privatevirtual

Definition at line 174 of file imex_sweeper_impl.hpp.

References plot::dt, ML_CVLOG, pfasst::encap::solution, and plot::t.

template<typename time >

void pfasst::encap::IMEXSweeper< time >::predict_without_left ( bool initial )

privatevirtual

Definition at line 203 of file imex_sweeper_impl.hpp.

References plot::dt, ML_CVLOG, pfasst::encap::solution, plot::t, and UNUSED.

template<typename time >

void pfasst::encap::IMEXSweeper< time >::reevaluate ( bool initial_only )

overridevirtual

Re-evaluate function values.

Reimplemented from pfasst::encap::EncapSweeper< time >.

Definition at line 98 of file imex_sweeper_impl.hpp.

References plot::dt, and plot::t.

template<typename time >

void pfasst::encap::IMEXSweeper< time >::residual	(	time	dt,
		vector< shared_ptr< Encapsulation< time >>>	dst
	)		const

overridevirtual

Compute residual at each SDC node (including FAS corrections).

Parameters

[in]	dt	width of time interval to integrate over
[in,out]	dst	residuals

Reimplemented from pfasst::encap::EncapSweeper< time >.

Definition at line 127 of file imex_sweeper_impl.hpp.

template<typename time >

void pfasst::encap::IMEXSweeper< time >::setup ( bool coarse )

overridevirtual

Setup (allocate etc) the sweeper.

Parameters

[in] coarse true if this sweeper exists on a coarsened MLSDC or PFASST level. This implies that space for an FAS correction and "saved" solutions are necessary.

Reimplemented from pfasst::encap::EncapSweeper< time >.

Definition at line 25 of file imex_sweeper_impl.hpp.

References pfasst::encap::function, pfasst::encap::EncapSweeper< time >::setup(), and pfasst::encap::solution.

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template<typename time >

void pfasst::encap::IMEXSweeper< time >::sweep ( )

overridevirtual

Perform one SDC sweep/iteration.

This computes a high-order solution from the previous iteration's function values and corrects it using forward/backward Euler steps across the nodes.

Implements pfasst::ISweeper< time >.

Definition at line 71 of file imex_sweeper_impl.hpp.

template<typename time >

void pfasst::encap::IMEXSweeper< time >::sweep_with_left ( )

privatevirtual

Definition at line 236 of file imex_sweeper_impl.hpp.

References plot::dt, pfasst::encap::EncapSweeper< time >::get_nodes(), ML_CVLOG, pfasst::encap::solution, and plot::t.

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template<typename time >

void pfasst::encap::IMEXSweeper< time >::sweep_without_left ( )

privatevirtual

Definition at line 275 of file imex_sweeper_impl.hpp.

References plot::dt, pfasst::encap::EncapSweeper< time >::get_nodes(), ML_CVLOG, pfasst::encap::solution, and plot::t.

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Member Data Documentation

template<typename time = time_precision>

vector<shared_ptr<Encapsulation<time> > > pfasst::encap::IMEXSweeper< time >::fs_expl

protected

Values of the explicit part of the right hand side \( F_{expl}(t,u) \) at all time nodes of the current iteration.

Definition at line 49 of file imex_sweeper.hpp.

template<typename time = time_precision>

shared_ptr<Encapsulation<time> > pfasst::encap::IMEXSweeper< time >::fs_expl_start

protected

Definition at line 50 of file imex_sweeper.hpp.

template<typename time = time_precision>

vector<shared_ptr<Encapsulation<time> > > pfasst::encap::IMEXSweeper< time >::fs_impl

protected

Values of the implicit part of the right hand side \( F_{impl}(t,u) \) at all time nodes of the current iteration.

Definition at line 56 of file imex_sweeper.hpp.

template<typename time = time_precision>

vector<shared_ptr<Encapsulation<time> > > pfasst::encap::IMEXSweeper< time >::s_integrals

protected

Node-to-node integrals of \( F(t,u) \) at all time nodes of the current iteration.

Definition at line 43 of file imex_sweeper.hpp.

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

include/pfasst/encap/imex_sweeper.hpp
src/pfasst/encap/imex_sweeper_impl.hpp

Public Member Functions

Protected Member Functions

Protected Attributes

Private Member Functions

Detailed Description

template<typename time = time_precision> class pfasst::encap::IMEXSweeper< time >

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation

template<typename time = time_precision>
class pfasst::encap::IMEXSweeper< time >