smith::mfem_ext::FirstOrderODE Class Reference

FirstOrderODE is a class wrapping mfem::TimeDependentOperator so that the user can use std::function to define the implementations of mfem::TimeDependentOperator::Mult and mfem::TimeDependentOperator::ImplicitSolve. More...

#include <odes.hpp>

Collaboration diagram for smith::mfem_ext::FirstOrderODE:

Classes
struct	State
	A set of references to physics-module-owned variables used by the residual operator. More...

Public Member Functions
	FirstOrderODE (int n, FirstOrderODE::State &&state, const EquationSolver &solver, const BoundaryConditionManager &bcs)
	Constructor defining the size and specific system of ordinary differential equations to be solved. More...
void	Mult (const mfem::Vector &u, mfem::Vector &du_dt) const
	Solves the equation du_dt = f(u, t) More...
void	ImplicitSolve (const double dt, const mfem::Vector &u, mfem::Vector &du_dt)
	Solves the equation du_dt = f(u + dt * du_dt, t) More...
void	SetEnforcementMethod (const DirichletEnforcementMethod method)
	Configures the Dirichlet enforcement method to use. More...
void	SetTimestepper (const smith::TimestepMethod timestepper)
	Set the time integration method. More...
void	Step (mfem::Vector &x, double &time, double &dt)
	Performs a time step. More...
TimestepMethod	GetTimestepper ()
	Query the timestep method for the ode solver. More...

Static Public Attributes
static constexpr double	epsilon = 0.000001
	a small number used to compute finite difference approximations to time derivatives of boundary conditions. More...

Detailed Description

FirstOrderODE is a class wrapping mfem::TimeDependentOperator so that the user can use std::function to define the implementations of mfem::TimeDependentOperator::Mult and mfem::TimeDependentOperator::ImplicitSolve.

The main benefit of this approach is that lambda capture lists allow for a flexible inline representation of the overloaded functions, without having to manually define a separate functor class.

Definition at line 240 of file odes.hpp.

Constructor & Destructor Documentation

FirstOrderODE()

smith::mfem_ext::FirstOrderODE::FirstOrderODE	(	int	n,
		FirstOrderODE::State &&	state,
		const EquationSolver &	solver,
		const BoundaryConditionManager &	bcs
	)

Constructor defining the size and specific system of ordinary differential equations to be solved.

Parameters

[in]	n	The number of components in each vector of the ODE
[in]	state	The collection of references to input/output variables from the physics module
[in]	solver	The solver that operates on the residual
[in]	bcs	The set of Dirichlet conditions to enforce

Implements mfem::TimeDependentOperator::Mult and mfem::TimeDependentOperator::ImplicitSolve (described in more detail here: https://mfem.github.io/doxygen/html/classmfem_1_1TimeDependentOperator.html)

where

mfem::TimeDependentOperator::Mult corresponds to the case where dt is zero mfem::TimeDependentOperator::ImplicitSolve corresponds to the case where dt is nonzero

Definition at line 253 of file odes.cpp.

Member Function Documentation

GetTimestepper()

TimestepMethod smith::mfem_ext::FirstOrderODE::GetTimestepper ( )

inline

Query the timestep method for the ode solver.

Returns

The timestep method used by the underlying ode solver

Definition at line 357 of file odes.hpp.

ImplicitSolve()

void smith::mfem_ext::FirstOrderODE::ImplicitSolve ( const double  dt, const mfem::Vector &  u, mfem::Vector &  du_dt  )

inline

Solves the equation du_dt = f(u + dt * du_dt, t)

Parameters

[in]	dt	The time step
[in]	u	The true DOFs
[in]	du_dt	The first time derivative of u

Definition at line 319 of file odes.hpp.

Mult()

void smith::mfem_ext::FirstOrderODE::Mult ( const mfem::Vector &  u, mfem::Vector &  du_dt  ) const

inline

Solves the equation du_dt = f(u, t)

Parameters

[in]	u	The true DOFs
[in]	du_dt	The first time derivative of u

Definition at line 310 of file odes.hpp.

SetEnforcementMethod()

void smith::mfem_ext::FirstOrderODE::SetEnforcementMethod ( const DirichletEnforcementMethod  method )

inline

Configures the Dirichlet enforcement method to use.

Parameters

[in]

method

The selected method

Definition at line 325 of file odes.hpp.

SetTimestepper()

void smith::mfem_ext::FirstOrderODE::SetTimestepper

(

const smith::TimestepMethod

timestepper

)

Set the time integration method.

Parameters

[in]

timestepper

The timestepping method for the solver

Definition at line 264 of file odes.cpp.

Step()

void smith::mfem_ext::FirstOrderODE::Step ( mfem::Vector &  x, double &  time, double &  dt  )

inline

Performs a time step.

Parameters

[in,out]	x	The predicted solution
[in,out]	time	The current time
[in,out]	dt	The desired time step

See also

mfem::ODESolver::Step

Definition at line 343 of file odes.hpp.

Member Data Documentation

epsilon

constexpr double smith::mfem_ext::FirstOrderODE::epsilon = 0.000001

staticconstexpr

a small number used to compute finite difference approximations to time derivatives of boundary conditions.

Note: this is intended to be temporary Ideally, epsilon should be "small" relative to the characteristic time of the ODE, but we can't ensure that at present (we don't have a critical timestep estimate)

Definition at line 251 of file odes.hpp.

---

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

• src/smith/numerics/odes.hpp
• src/smith/numerics/odes.cpp