This is a class for evaluating exponentials. More...

#include "src/ExpEvaluator.h"

Public Member Functions
	ExpEvaluator ()
	Constructor initializes array pointers to NULL. More...

virtual	~ExpEvaluator ()
	Destructor deletes table for linear interpolation of exponentials.

void	setQuadrature (Quadrature *quadrature)
	Set the Quadrature to use when computing exponentials. More...

void	setMaxOpticalLength (FP_PRECISION max_optical_length)
	Sets the maximum optical length covered in the exponential interpolation table. More...

void	setExpPrecision (FP_PRECISION exp_precision)
	Sets the maximum acceptable approximation error for exponentials. More...

void	useInterpolation ()
	Use linear interpolation to compute exponentials.

void	useIntrinsic ()
	Use the exponential intrinsic exp(...) to compute exponentials.

void	useLinearSource ()
	Use linear source exponentials.

FP_PRECISION	getMaxOpticalLength ()
	Gets the maximum optical length covered with the exponential interpolation table. More...

FP_PRECISION	getExpPrecision ()
	Gets the maximum acceptable approximation error for exponentials. More...

bool	isUsingInterpolation ()
	Returns true if using linear interpolation to compute exponentials. More...

FP_PRECISION	getTableSpacing ()
	Returns the exponential table spacing. More...

int	getTableSize ()
	Get the number of entries in the exponential interpolation table. More...

FP_PRECISION *	getExpTable ()
	Returns a pointer to the exponential interpolation table. More...

int	getExponentialIndex (FP_PRECISION tau)
	Get the index on the exponential interpolation grid of the value right beneath tau. More...

FP_PRECISION	getDifference (int index, FP_PRECISION tau)
	Compute the difference between an optical path and an indexed value in the exponential interpolation grid. More...

FP_PRECISION	convertDistance3Dto2D (FP_PRECISION length)
	Convert a 3D distance to a 2D based on the evaluator's polar angle. More...

FP_PRECISION	getInverseSinTheta ()
	Get the inverse of sin theta from the ExpEvaluator. More...

void	initialize (int azim_index, int polar_index, bool solve_3D)
	If using linear interpolation, builds the table for each polar angle. More...

FP_PRECISION	computeExponential (FP_PRECISION tau, int polar_offset)
	Computes the F1 exponential term. More...

FP_PRECISION	computeExponentialF1 (int index, int polar_offset, FP_PRECISION dt, FP_PRECISION dt2)
	Computes the F1 exponential term. More...

FP_PRECISION	computeExponentialF2 (int index, int polar_offset, FP_PRECISION dt, FP_PRECISION dt2)
	Computes the F2 exponential term. More...

FP_PRECISION	computeExponentialH (int index, int polar_offset, FP_PRECISION dt, FP_PRECISION dt2)
	Computes the H exponential term. More...

void	retrieveExponentialComponents (FP_PRECISION tau, int polar_offset, FP_PRECISION exp_F1, FP_PRECISION exp_F2, FP_PRECISION *exp_H)
	Computes the F1, F2, H exponential term. More...

FP_PRECISION	computeExponentialG2 (FP_PRECISION tau)
	Computes the G2 exponential term for a optical length and polar angle. More...

ExpEvaluator *	deepCopy ()
	Deep copies an ExpEvaluator, for developing purposes. More...

Detailed Description

This is a class for evaluating exponentials.

The ExpEvaluator includes different algorithms to evaluate exponentials with varying degrees of accuracy and speed. This is a helper class for the Solver and its subclasses and it is not intended to be initialized as a standalone object.

Constructor & Destructor Documentation

◆ ExpEvaluator()

ExpEvaluator::ExpEvaluator ( )

Constructor initializes array pointers to NULL.

The constructor sets the interpolation scheme as the default for computing exponentials.

Member Function Documentation

◆ computeExponential()

FP_PRECISION ExpEvaluator::computeExponential	(	FP_PRECISION	tau,
		int	polar_offset
	)

inline

Computes the F1 exponential term.

Parameters

tau	the optical distance (2D)
polar_offset	an offset to the index in the look-up table

Returns: the F1 exponential term

◆ computeExponentialF1()

FP_PRECISION ExpEvaluator::computeExponentialF1	(	int	index,
		int	polar_offset,
		FP_PRECISION	dt,
		FP_PRECISION	dt2
	)

inline

Computes the F1 exponential term.

This method computes F1 exponential from Ferrer [1] given an index into the exponential look-up table, the distance (in units of optical length) from the corresponding table value and the requested tau, and that distance squared. This method uses either a linear interpolation table (default) or the exponential intrinsic exp(...) function. //DEPRECATED

[1] R. Ferrer and J. Rhodes III, "A Linear Source Approximation Scheme for the Method of Characteristics", Nuclear Science and Engineering, Volume 182, February 2016.

Parameters

index	the index into the exponential look-up table
polar_offset	an offset to the index in the look-up table
dt	the distance to the corresponding look-up table bin
dt2	the distance to the corresponding look-up table bin squared

Returns: the evaluated F1 exponential term

◆ computeExponentialF2()

FP_PRECISION ExpEvaluator::computeExponentialF2	(	int	index,
		int	polar_offset,
		FP_PRECISION	dt,
		FP_PRECISION	dt2
	)

inline

Computes the F2 exponential term.

This method computes F2 exponential from Ferrer [1] given an index into the exponential look-up table, the distance (in units of optical length) from the corresponding table value and the requested tau, and that distance squared. This method uses either a linear interpolation table (default) or the exponential intrinsic exp(...) function. //DEPRECATED

[1] R. Ferrer and J. Rhodes III, "A Linear Source Approximation Scheme for the Method of Characteristics", Nuclear Science and Engineering, Volume 182, February 2016.

Parameters

index	the index into the exponential look-up table
polar_offset	an offset to the index in the look-up table
dt	the distance to the corresponding look-up table bin
dt2	the distance to the corresponding look-up table bin squared

Returns: the evaluated F2 exponential term

◆ computeExponentialG2()

FP_PRECISION ExpEvaluator::computeExponentialG2 ( FP_PRECISION tau )

inline

Computes the G2 exponential term for a optical length and polar angle.

This method computes the G2 exponential term from Ferrer [1] for some optical path length and polar angle. This method uses a rational fraction approximation to compute the exponential term.

[1] R. Ferrer and J. Rhodes III, "A Linear Source Approximation Scheme for the Method of Characteristics", Nuclear Science and Engineering, Volume 182, February 2016.

Parameters

tau	the optical path length (e.g., sigma_t times length)

Returns: the evaluated exponential

◆ computeExponentialH()

FP_PRECISION ExpEvaluator::computeExponentialH	(	int	index,
		int	polar_offset,
		FP_PRECISION	dt,
		FP_PRECISION	dt2
	)

inline

Computes the H exponential term.

This method computes H exponential from Ferrer [1] given an index into the exponential look-up table, the distance (in units of optical length) from the corresponding table value and the requested tau, and that distance squared. This method uses either a linear interpolation table (default) or the exponential intrinsic exp(...) function. //DEPRECATED

[1] R. Ferrer and J. Rhodes III, "A Linear Source Approximation Scheme for the Method of Characteristics", Nuclear Science and Engineering, Volume 182, February 2016.

Parameters

index	the index into the exponential look-up table
polar_offset	an offset to the index in the look-up table
dt	the distance to the corresponding look-up table bin
dt2	the distance to the corresponding look-up table bin squared

Returns: the evaluated H exponential term

◆ convertDistance3Dto2D()

FP_PRECISION ExpEvaluator::convertDistance3Dto2D ( FP_PRECISION length )

inline

Convert a 3D distance to a 2D based on the evaluator's polar angle.

Parameters

length the 3D distance

Returns: the 2D distance

◆ deepCopy()

ExpEvaluator * ExpEvaluator::deepCopy ( )

Deep copies an ExpEvaluator, for developing purposes.

Returns: the copied ExpEvaluator

◆ getDifference()

FP_PRECISION ExpEvaluator::getDifference	(	int	index,
		FP_PRECISION	tau
	)

inline

Compute the difference between an optical path and an indexed value in the exponential interpolation grid.

Parameters

index	index on the exponential interpolation grid
tau	optical distance

Returns: the difference between tau and the value on the grid

◆ getExponentialIndex()

int ExpEvaluator::getExponentialIndex ( FP_PRECISION tau )

inline

Get the index on the exponential interpolation grid of the value right beneath tau.

Parameters

tau	optical distance

Returns: the index on the exponential interpolation grid

◆ getExpPrecision()

FP_PRECISION ExpEvaluator::getExpPrecision ( )

Gets the maximum acceptable approximation error for exponentials.

Returns: the maximum exponential approximation error

◆ getExpTable()

FP_PRECISION * ExpEvaluator::getExpTable ( )

Returns a pointer to the exponential interpolation table.

Returns: pointer to the exponential interpolation table

◆ getInverseSinTheta()

FP_PRECISION ExpEvaluator::getInverseSinTheta ( )

inline

Get the inverse of sin theta from the ExpEvaluator.

Returns: inverse sin theta for the first angle

◆ getMaxOpticalLength()

FP_PRECISION ExpEvaluator::getMaxOpticalLength ( )

Gets the maximum optical length covered with the exponential interpolation table.

Returns: max_optical_length the maximum optical length

◆ getTableSize()

int ExpEvaluator::getTableSize ( )

Get the number of entries in the exponential interpolation table.

Returns: entries in the interpolation table

◆ getTableSpacing()

FP_PRECISION ExpEvaluator::getTableSpacing ( )

Returns the exponential table spacing.

Returns: exponential table spacing

◆ initialize()

void ExpEvaluator::initialize	(	int	azim_index,
		int	polar_index,
		bool	solve_3D
	)

If using linear interpolation, builds the table for each polar angle.

Parameters

azim_index	the azimuthal index to get the adjusted polar angle in 3D
polar_index	the polar angle index
solve_3D	whether the geometry is 3D or not

◆ isUsingInterpolation()

bool ExpEvaluator::isUsingInterpolation ( )

Returns true if using linear interpolation to compute exponentials.

Returns: true if so, false otherwise

◆ retrieveExponentialComponents()

void ExpEvaluator::retrieveExponentialComponents	(	FP_PRECISION	tau,
		int	polar_offset,
		FP_PRECISION *	exp_F1,
		FP_PRECISION *	exp_F2,
		FP_PRECISION *	exp_H
	)

inline

Computes the F1, F2, H exponential term.

This method computes F1, F2, H exponential from Ferrer [1] given the requested tau. This method uses either a linear interpolation table (default) or the exponential intrinsicexp(...) function.

[1] R. Ferrer and J. Rhodes III, "A Linear Source Approximation Scheme for the Method of Characteristics", Nuclear Science and Engineering, Volume 182, February 2016.

Parameters

tau	the requested tau
polar_offset	an offset to the index in the look-up table
exp_F1	pointer to the F1 exponential term to be computed
exp_F2	pointer to the F2 exponential term to be computed
exp_H	pointer to the H exponential term to be computed

◆ setExpPrecision()

void ExpEvaluator::setExpPrecision ( FP_PRECISION exp_precision )

Sets the maximum acceptable approximation error for exponentials.

This routine only affects the construction of the linear interpolation table for exponentials, if in use. By default, a value of 1E-5 is used for the table, as recommended by the analysis of Yamamoto in his 2004 paper on the subject.

Parameters

exp_precision the maximum exponential approximation error

◆ setMaxOpticalLength()

void ExpEvaluator::setMaxOpticalLength ( FP_PRECISION max_optical_length )

Sets the maximum optical length covered in the exponential interpolation table.

Parameters

max_optical_length the maximum optical length

◆ setQuadrature()

void ExpEvaluator::setQuadrature ( Quadrature * quadrature )

Set the Quadrature to use when computing exponentials.

Parameters

quadrature a Quadrature object pointer

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

/home/guillaume/Research/OpenMOC/src/ExpEvaluator.h
/home/guillaume/Research/OpenMOC/src/ExpEvaluator.cpp

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ ExpEvaluator()

Member Function Documentation

◆ computeExponential()

◆ computeExponentialF1()

◆ computeExponentialF2()

◆ computeExponentialG2()

◆ computeExponentialH()

◆ convertDistance3Dto2D()

◆ deepCopy()

◆ getDifference()

◆ getExponentialIndex()

◆ getExpPrecision()

◆ getExpTable()

◆ getInverseSinTheta()

◆ getMaxOpticalLength()

◆ getTableSize()

◆ getTableSpacing()

◆ initialize()

◆ isUsingInterpolation()

◆ retrieveExponentialComponents()

◆ setExpPrecision()

◆ setMaxOpticalLength()

◆ setQuadrature()