Description

template<unsigned int internalCounterBits = 64>
class gmx::ThreeFry2x64Fast< internalCounterBits >

ThreeFry2x64 random engine with 13 iteractions.

Template Parameters

internalCounterBits,default 64.

This class provides relatively high quality random numbers that only fail one BigCrush test, and it is a bit faster than the 20-round version. It works with two 64-bit values each for keys and counters, and is most efficient when we only need a few random values before restarting the counters with new values.

Public Member Functions
	ThreeFry2x64Fast (gmx_uint64_t key0=0, RandomDomain domain=RandomDomain::Other)
	Construct ThreeFry random engine with 2x64 key values, 13 rounds. More...

	ThreeFry2x64Fast (gmx_uint64_t key0, gmx_uint64_t key1)
	Construct ThreeFry random engine from 2x64-bit unsigned integers, 13 rounds. More...

Public Member Functions inherited from gmx::ThreeFry2x64General< 13, internalCounterBits >
	ThreeFry2x64General (gmx_uint64_t key0=0, RandomDomain domain=RandomDomain::Other)
	Construct random engine with 2x64 key values. More...

	ThreeFry2x64General (gmx_uint64_t key0, gmx_uint64_t key1)
	Construct random engine from 2x64-bit unsigned integers. More...

void	seed (gmx_uint64_t key0=0, RandomDomain domain=RandomDomain::Other)
	Seed 2x64 random engine with two 64-bit key values. More...

void	seed (gmx_uint64_t key0, gmx_uint64_t key1)
	Seed random engine from 2x64-bit unsigned integers. More...

void	restart (gmx_uint64_t ctr0=0, gmx_uint64_t ctr1=0)
	Restart 2x64 random engine counter from 2 64-bit values. More...

result_type	operator() ()
	Generate the next random number. More...

void	discard (gmx_uint64_t n)
	Skip next n random numbers. More...

bool	operator== (const ThreeFry2x64General< rounds, internalCounterBits > &x) const
	Return true if two ThreeFry2x64 engines are identical. More...

bool	operator!= (const ThreeFry2x64General< rounds, internalCounterBits > &x) const
	Return true of two ThreeFry2x64 engines are not identical. More...

Additional Inherited Members
Public Types inherited from gmx::ThreeFry2x64General< 13, internalCounterBits >
typedef gmx_uint64_t	result_type
	Integer type for output.

typedef std::array < result_type, 2 >	counter_type
	Use array for counter & key states so it is allocated on the stack.

Static Public Member Functions inherited from gmx::ThreeFry2x64General< 13, internalCounterBits >
static constexpr result_type	min ()
	Smallest value that can be returned from random engine.

static constexpr result_type	max ()
	Largest value that can be returned from random engine.

Constructor & Destructor Documentation

template<unsigned int internalCounterBits = 64>

gmx::ThreeFry2x64Fast< internalCounterBits >::ThreeFry2x64Fast	(	gmx_uint64_t	key0 = `0`,
		RandomDomain	domain = `RandomDomain::Other`
	)

inline

Construct ThreeFry random engine with 2x64 key values, 13 rounds.

Parameters

key0	Random seed in the form of a 64-bit unsigned value.
domain	Random domain. This is used to guarantee that different applications of a random engine inside the code get different streams of random numbers, without requiring the user to provide lots of random seeds. Pick a value from the RandomDomain class, or RandomDomain::Other if it is not important. In the latter case you might want to use gmx::DefaultRandomEngine instead.

Note: The random domain is really another 64-bit seed value.

Exceptions

InternalError if the high bits needed to encode the number of counter bits are nonzero.

template<unsigned int internalCounterBits = 64>

gmx::ThreeFry2x64Fast< internalCounterBits >::ThreeFry2x64Fast	(	gmx_uint64_t	key0,
		gmx_uint64_t	key1
	)

inline

Construct ThreeFry random engine from 2x64-bit unsigned integers, 13 rounds.

This constructor assigns the raw 128 bit key data from unsigned integers. It is meant for the case when you want full control over the key, for instance to compare with reference values of the ThreeFry function during testing.

Parameters

key0	First word of key/random seed.
key1	Second word of key/random seed.

Exceptions

InternalError if the high bits needed to encode the number of counter bits are nonzero. To test arbitrary values, use 0 internal counter bits.

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

src/gromacs/random/threefry.h

Description

template<unsigned int internalCounterBits = 64> class gmx::ThreeFry2x64Fast< internalCounterBits >

Public Member Functions

Additional Inherited Members

Constructor & Destructor Documentation

template<unsigned int internalCounterBits = 64>
class gmx::ThreeFry2x64Fast< internalCounterBits >