NumLib::BackwardEuler Class Reference

Detailed Description

Backward Euler scheme.

Definition at line 127 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.
void	nextTimestep (const double t, const double delta_t) override
double	getCurrentTime () const override
double	getCurrentTimeIncrement () const override
double	getPreviousTimeIncrement () const override
	Returns the value of \(\Delta t\) from the previous time step.
void	getWeightedOldX (GlobalVector &y, GlobalVector const &x_old) const override
	Returns \( x_O \).
Public Member Functions inherited from NumLib::TimeDiscretization
	TimeDiscretization ()=default
virtual	~TimeDiscretization ()=default

Private Attributes
double	_t = std::numeric_limits<double>::quiet_NaN()
	\( t_C \)
double	_delta_t
	the timestep size
double	_delta_t_prev = std::numeric_limits<double>::quiet_NaN()
	The timestep size of the previous timestep.

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 138 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 139 of file TimeDiscretization.h.

{ return _delta_t; }

References _delta_t.

getPreviousTimeIncrement()

double NumLib::BackwardEuler::getPreviousTimeIncrement ( ) const

inlineoverridevirtual

Returns the value of \(\Delta t\) from the previous time step.

Implements NumLib::TimeDiscretization.

Definition at line 140 of file TimeDiscretization.h.

{ return _delta_t_prev; }

References _delta_t_prev.

getWeightedOldX()

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

overridevirtual

Returns \( x_O \).

Implements NumLib::TimeDiscretization.

Definition at line 18 of file TimeDiscretization.cpp.

{
    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 131 of file TimeDiscretization.h.

    {
        _delta_t_prev = _delta_t;
        _t = t;
        _delta_t = delta_t;
    }

References _delta_t, _delta_t_prev, and _t.

setInitialState()

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

inlineoverridevirtual

Sets the initial condition.

Implements NumLib::TimeDiscretization.

Definition at line 130 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 146 of file TimeDiscretization.h.

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

_delta_t_prev

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

private

The timestep size of the previous timestep.

Definition at line 150 of file TimeDiscretization.h.

Referenced by getPreviousTimeIncrement(), and nextTimestep().

_t

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

private

\( t_C \)

Definition at line 145 of file TimeDiscretization.h.

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

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

• NumLib/ODESolver/TimeDiscretization.h
• NumLib/ODESolver/TimeDiscretization.cpp