Functions
uint64_t	RandomToolbox::GetHash (unsigned long nodeIndex, unsigned short iDim, unsigned long timeIter)
	Generate a deterministic 64-bit hash from three integers.

double	RandomToolbox::HashToUniform (uint64_t x)
	Convert a 64-bit hash into a uniform double in (0,1]. Uses the top 53 bits of the hash to fill the mantissa of a double. Ensures the result is never zero, suitable for Box-Muller transform.

double	RandomToolbox::HashToNormal (uint64_t x)
	Generate a standard normal random number from a 64-bit hash. Uses two deterministic uniforms derived from the hash and its bitwise NOT as inputs to the Box-Muller transform.

double	RandomToolbox::GetNormal (unsigned long nodeIndex, unsigned long dim, unsigned long timeIter)
	Generate a deterministic standard normal number for a cell, dimension, and timestep.

template<class T >
T	RandomToolbox::GetBesselZero (const T &x)
	Compute modified bessel function of first kind (order 0).

template<class T >
T	RandomToolbox::GetBesselIntegral (const T &beta_x, const T &beta_y, const T &beta_z)
	Compute integral involving the product of three modified Bessel functions. Useful for scaling the smoothed stochastic source terms in Langevin equations.

Detailed Description

Function Documentation

◆ GetBesselIntegral()

template<class T >

T RandomToolbox::GetBesselIntegral	(	const T &	beta_x,
		const T &	beta_y,
		const T &	beta_z
	)

inline

Compute integral involving the product of three modified Bessel functions. Useful for scaling the smoothed stochastic source terms in Langevin equations.

Parameters

[in]	beta_x	Argument in x-direction.
[in]	beta_y	Argument in y-direction.
[in]	beta_z	Argument in z-direction.

Returns: Value of the integral.

◆ GetBesselZero()

template<class T >

T RandomToolbox::GetBesselZero ( const T & x )

inline

Compute modified bessel function of first kind (order 0).

Parameters

[in] x Argument of Bessel funtion.

Returns: Value of Bessel function.

◆ GetHash()

uint64_t RandomToolbox::GetHash	(	unsigned long	nodeIndex,
		unsigned short	iDim,
		unsigned long	timeIter
	)

inline

Generate a deterministic 64-bit hash from three integers.

Parameters

[in]	nodeIndex	Global node index.
[in]	iDim	Dimension index.
[in]	timeIter	Current time iteration of the simulation.

Returns: 64-bit hash value.

◆ GetNormal()

double RandomToolbox::GetNormal	(	unsigned long	nodeIndex,
		unsigned long	dim,
		unsigned long	timeIter
	)

inline

Generate a deterministic standard normal number for a cell, dimension, and timestep.

Combines hashing and Box-Muller in one function.

Parameters

[in]	nodeIndex	Global node index.
[in]	dim	Dimension index.
[in]	timeIter	Simulation timestep (1-based).

Returns: Standard normal random number.

◆ HashToNormal()

double RandomToolbox::HashToNormal ( uint64_t x )

inline

Generate a standard normal random number from a 64-bit hash. Uses two deterministic uniforms derived from the hash and its bitwise NOT as inputs to the Box-Muller transform.

Parameters

[in] x 64-bit hash.

Returns: Standard normal random number (mean=0, stddev=1).

◆ HashToUniform()

double RandomToolbox::HashToUniform ( uint64_t x )

inline

Convert a 64-bit hash into a uniform double in (0,1]. Uses the top 53 bits of the hash to fill the mantissa of a double. Ensures the result is never zero, suitable for Box-Muller transform.

Parameters

[in] x 64-bit hash.

Returns: Uniform double in the interval (0,1].

Functions

Detailed Description

Function Documentation

◆ GetBesselIntegral()

◆ GetBesselZero()

◆ GetHash()

◆ GetNormal()

◆ HashToNormal()

◆ HashToUniform()