criptic::RngThread Class Reference

Thread-safe random number generator. More...

#include <RngThread.H>

Public Member Functions
	RngThread (const ParmParser &pp)
	Constructs an RngThread object.
	RngThread (std::string &buf)
	Constructs an RngThread object from a serialized buffer.
	~RngThread ()
	Free RngThread object memory.
Real	uniform (const Real a=0.0, const Real b=1.0) const
	Return a random number uniformly-distributed in (a,b)
IdxType	uniformInt (const IdxType a=0, const IdxType b=maxIdx) const
	Return a random integer uniformly-distributed in (a,b)
Real	normal (const Real mean=0.0, const Real stddev=1.0) const
	Return a normally-distributed random number.
IdxType	poisson (const Real ex) const
	Return an integer drawn from a Poisson distribution.
template<typename T >
T &	choose (std::vector< T > &elem, const std::vector< Real > &w=std::vector< Real >()) const
	Randomly choose an element from a vector.
template<typename T >
const T &	choose (const std::vector< T > &elem, const std::vector< Real > &w=std::vector< Real >()) const
	Randomly choose an element from a const vector.
const std::string	getState () const
	Get a serialized buffer holding the RNG state.
void	setState (const std::string &buf)
	Restore the RNG state from a buffer.

Static Public Member Functions
static IdxType	stateSize ()
	Return the number of bytes in the RNG state buffer.

Private Attributes
ThreadVec< pcg64 * >	r

Detailed Description

Thread-safe random number generator.

This class implements a thread-safe random number generator, based on the pcg family of random number generators. Each thread maintains a separate, private random stream, and calls to the random number generator from a given thread are automatically drawn from the correct stream.

Constructor & Destructor Documentation

RngThread() [1/2]

RngThread::RngThread

(

const ParmParser &

pp

)

Constructs an RngThread object.

Parameters

pp	The parameter parser, which contains the input deck

RngThread() [2/2]

RngThread::RngThread

(

std::string &

buf

)

Constructs an RngThread object from a serialized buffer.

Parameters

buf	A string containing the serialized state

~RngThread()

RngThread::~RngThread

(

)

Free RngThread object memory.

Member Function Documentation

choose() [1/2]

template<typename T >

const T & criptic::RngThread::choose ( const std::vector< T > &  elem, const std::vector< Real > &  w = std::vector<Real>()  ) const

inline

Randomly choose an element from a const vector.

Template Parameters

T	Type held by vector

Parameters

elem	Vector of elements from which to choose
w	Relative probability of each element

Returns

Const reference to a randomly selected element of elem

If w is an empty vector, or an argument is not provided, all elements are treated as having equal probability. The sum of w need not be normalized to 1. It is an error if w has a non-zero size that is different than the size of elem.

choose() [2/2]

template<typename T >

T & criptic::RngThread::choose ( std::vector< T > &  elem, const std::vector< Real > &  w = std::vector<Real>()  ) const

inline

Randomly choose an element from a vector.

Template Parameters

T	Type held by vector

Parameters

elem	Vector of elements from which to choose
w	Relative probability of each element

Returns

Reference to a randomly selected element of elem

If w is an empty vector, or an argument is not provided, all elements are treated as having equal probability. The sum of w need not be normalized to 1. It is an error if w has a non-zero size that is different than the size of elem.

getState()

const std::string RngThread::getState

(

)

const

Get a serialized buffer holding the RNG state.

Returns

A string holding a serialized buffer containing the RNG state

The buffer returned by this routine can be supplied to the setState routine to restore the RNG state. Note that save-restore is only available when the maximum number of openMP threads is the same between the saved and restored states. If the number of threads differs, the resulting behavior is undefined; it is the responsibility of the calling program to ensure consistency.

normal()

Real criptic::RngThread::normal ( const Real  mean = 0.0, const Real  stddev = 1.0  ) const

inline

Return a normally-distributed random number.

Parameters

mean	Central value of distribution
stddev	Standard deviation of distribution

Returns

A random number drawn from a normal distribution

poisson()

IdxType criptic::RngThread::poisson ( const Real  ex ) const

inline

Return an integer drawn from a Poisson distribution.

Parameters

ex	Expectation value of Poisson distribution

Returns

A random integer

setState()

void RngThread::setState

(

const std::string &

buf

)

Restore the RNG state from a buffer.

Parameters

buf	A string containing the serialized state

This routine operates on a stream provided by getState. Save-restore functionality only works if the maximum number of openMP threads is the same between the saved and restored states. If the number of threads differs, the resulting behavior is undefined; it is the responsibility of the calling program to ensure consistency.

stateSize()

IdxType RngThread::stateSize ( )

static

Return the number of bytes in the RNG state buffer.

Returns

Number of characters in the RNG state buffer

This method is defined as static so that it can be called without access to any particular RNG.

uniform()

Real criptic::RngThread::uniform ( const Real  a = 0.0, const Real  b = 1.0  ) const

inline

Return a random number uniformly-distributed in (a,b)

Parameters

a	Minimum random value
b	Maximum random value

Returns

A random number in (a,b)

uniformInt()

IdxType criptic::RngThread::uniformInt ( const IdxType  a = 0, const IdxType  b = maxIdx  ) const

inline

Return a random integer uniformly-distributed in (a,b)

Parameters

a	Minimum random value
b	Maximum random value

Returns

A random integer in [a,b]

Member Data Documentation

r

ThreadVec<pcg64 *> criptic::RngThread::r

private

Pointers to rng engines

---

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

• Src/Utils/RngThread.H
• Src/Utils/RngThread.cpp