__gnu_parallel::_RandomNumber Class Reference

Random number generator, based on the Mersenne twister. More...

#include <parallel/random_number.h>

Public Member Functions
	_RandomNumber ()
	Default constructor. Seed with 0. More...
	_RandomNumber (uint32_t __seed, uint64_t _M_supremum=0x100000000ULL)
	Constructor. More...
uint32_t	operator() ()
	Generate unsigned random 32-bit integer. More...
uint32_t	operator() (uint64_t local_supremum)
	Generate unsigned random 32-bit integer in the interval [0,local_supremum). More...
unsigned long	__genrand_bits (int __bits)
	Generate a number of random bits, run-time parameter. More...

Static Private Member Functions
static uint32_t	__scale_down (uint64_t __x, uint64_t _M_supremum, double)

Private Attributes
std::tr1::mt19937	_M_mt
uint64_t	_M_supremum
uint64_t	_M_rand_sup
double	_M_supremum_reciprocal
double	_M_rand_sup_reciprocal
uint64_t	__cache
int	__bits_left

Detailed Description

Random number generator, based on the Mersenne twister.

Constructor & Destructor Documentation

__gnu_parallel::_RandomNumber::_RandomNumber ( )

inline

Default constructor. Seed with 0.

    : _M_mt(0), _M_supremum(0x100000000ULL),
      _M_rand_sup(1ULL << std::numeric_limits<uint32_t>::digits),
      _M_supremum_reciprocal(double(_M_supremum) / double(_M_rand_sup)),
      _M_rand_sup_reciprocal(1.0 / double(_M_rand_sup)),
      __cache(0), __bits_left(0) { }

__gnu_parallel::_RandomNumber::_RandomNumber ( uint32_t  __seed, uint64_t  _M_supremum = 0x100000000ULL  )

inline

Constructor.

Parameters

__seed	Random __seed.
_M_supremum	Generate integer random numbers in the interval [0,_M_supremum).

    : _M_mt(__seed), _M_supremum(_M_supremum),
      _M_rand_sup(1ULL << std::numeric_limits<uint32_t>::digits),
      _M_supremum_reciprocal(double(_M_supremum) / double(_M_rand_sup)),
      _M_rand_sup_reciprocal(1.0 / double(_M_rand_sup)),
      __cache(0), __bits_left(0) { }

Member Function Documentation

unsigned long __gnu_parallel::_RandomNumber::__genrand_bits ( int  __bits )

inline

Generate a number of random bits, run-time parameter.

Parameters

__bits

Number of bits to generate.

    {
      unsigned long __res = __cache & ((1 << __bits) - 1);
      __cache = __cache >> __bits;
      __bits_left -= __bits;
      if (__bits_left < 32)
        {
          __cache |= ((uint64_t(_M_mt())) << __bits_left);
          __bits_left += 32;
        }
      return __res;
    }

static uint32_t __gnu_parallel::_RandomNumber::__scale_down ( uint64_t  __x, uint64_t  _M_supremum, double    )

inlinestaticprivate

        {
#if _GLIBCXX_SCALE_DOWN_FPU
          return uint32_t(__x * _M_supremum_reciprocal);
#else
          return static_cast<uint32_t>(__x % _M_supremum);
#endif
        }

uint32_t __gnu_parallel::_RandomNumber::operator() ( )

inline

Generate unsigned random 32-bit integer.

    { return __scale_down(_M_mt(), _M_supremum, _M_supremum_reciprocal); }

uint32_t __gnu_parallel::_RandomNumber::operator() ( uint64_t  local_supremum )

inline

Generate unsigned random 32-bit integer in the interval [0,local_supremum).

    {
      return __scale_down(_M_mt(), local_supremum,
                        double(local_supremum * _M_rand_sup_reciprocal));
    }

Member Data Documentation

int __gnu_parallel::_RandomNumber::__bits_left

private

uint64_t __gnu_parallel::_RandomNumber::__cache

private

std::tr1::mt19937 __gnu_parallel::_RandomNumber::_M_mt

private

uint64_t __gnu_parallel::_RandomNumber::_M_rand_sup

private

double __gnu_parallel::_RandomNumber::_M_rand_sup_reciprocal

private

uint64_t __gnu_parallel::_RandomNumber::_M_supremum

private

double __gnu_parallel::_RandomNumber::_M_supremum_reciprocal

private

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

• GCC4/inc/parallel/random_number.h