NumLib::BackwardEuler Class Reference

Detailed Description

Backward Euler scheme.

Definition at line 157 of file TimeDiscretization.h.

#include <TimeDiscretization.h>

Inheritance diagram for NumLib::BackwardEuler:

Collaboration diagram for NumLib::BackwardEuler:

Public Member Functions
void	setInitialState (const double t0) override
	Sets the initial condition. More...
void	nextTimestep (const double t, const double delta_t) override
double	getCurrentTime () const override
double	getCurrentTimeIncrement () const override
double	getNewXWeight () const override
	Returns $\alpha = \partial \hat x / \partial x_N$. More...
void	getWeightedOldX (GlobalVector &y, GlobalVector const &x_old) const override
	Returns $x_O$. More...
Public Member Functions inherited from NumLib::TimeDiscretization
	TimeDiscretization ()=default
double	computeRelativeChangeFromPreviousTimestep (GlobalVector const &x, GlobalVector const &x_old, MathLib::VecNormType norm_type)
void	getXdot (GlobalVector const &x_at_new_timestep, GlobalVector const &x_old, GlobalVector &xdot) const
virtual	~TimeDiscretization ()=default

Private Attributes
double	_t = std::numeric_limits<double>::quiet_NaN()
	$t_C$ More...
double	_delta_t
	the timestep size More...

Additional Inherited Members
Protected Attributes inherited from NumLib::TimeDiscretization
std::unique_ptr< GlobalVector >	_dx
	Used to store $u_{n+1}-u_{n}$. More...

Member Function Documentation

getCurrentTime()

double NumLib::BackwardEuler::getCurrentTime ( ) const

inlineoverridevirtual

Returns $t_C$, i.e., the time at which the equation will be assembled.

Implements NumLib::TimeDiscretization.

Definition at line 168 of file TimeDiscretization.h.

{ return _t; }

References _t.

getCurrentTimeIncrement()

double NumLib::BackwardEuler::getCurrentTimeIncrement ( ) const

inlineoverridevirtual

Returns $\Delta t_C$, i.e., the time at which the equation will be assembled.

Implements NumLib::TimeDiscretization.

Definition at line 169 of file TimeDiscretization.h.

{ return _delta_t; }

References _delta_t.

getNewXWeight()

double NumLib::BackwardEuler::getNewXWeight ( ) const

inlineoverridevirtual

Returns $\alpha = \partial \hat x / \partial x_N$.

Implements NumLib::TimeDiscretization.

Definition at line 170 of file TimeDiscretization.h.

{ return 1.0 / _delta_t; }

References _delta_t.

getWeightedOldX()

void NumLib::BackwardEuler::getWeightedOldX ( GlobalVector &  y, GlobalVector const &  x_old  ) const

inlineoverridevirtual

Returns $x_O$.

Implements NumLib::TimeDiscretization.

Definition at line 171 of file TimeDiscretization.h.

    {
        namespace LinAlg = MathLib::LinAlg;
 
        // y = x_old / delta_t
        LinAlg::copy(x_old, y);
        LinAlg::scale(y, 1.0 / _delta_t);
    }

References _delta_t, MathLib::LinAlg::copy(), and MathLib::LinAlg::scale().

nextTimestep()

void NumLib::BackwardEuler::nextTimestep ( const double  t, const double  delta_t  )

inlineoverridevirtual

Indicate that the computation of a new timestep is being started now.

Warning

Currently changing timestep sizes are not supported. Thus, delta_t must not change throughout the entire time integration process! This is not checked by this code!

Implements NumLib::TimeDiscretization.

Definition at line 162 of file TimeDiscretization.h.

    {
        _t = t;
        _delta_t = delta_t;
    }

References _delta_t, and _t.

setInitialState()

void NumLib::BackwardEuler::setInitialState ( const double  t0 )

inlineoverridevirtual

Sets the initial condition.

Implements NumLib::TimeDiscretization.

Definition at line 160 of file TimeDiscretization.h.

{ _t = t0; }

References _t.

Member Data Documentation

_delta_t

double NumLib::BackwardEuler::_delta_t

private

Initial value:

=
        std::numeric_limits<double>::quiet_NaN()

the timestep size

Definition at line 183 of file TimeDiscretization.h.

Referenced by getCurrentTimeIncrement(), getNewXWeight(), getWeightedOldX(), and nextTimestep().

_t

double NumLib::BackwardEuler::_t = std::numeric_limits<double>::quiet_NaN()

private

$t_C$

Definition at line 182 of file TimeDiscretization.h.

Referenced by getCurrentTime(), nextTimestep(), and setInitialState().

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

• NumLib/ODESolver/TimeDiscretization.h