bsfm::math::RandomGenerator Class Reference

#include <random_generator.h>

Public Member Functions
	RandomGenerator (unsigned long seed)
int	Integer ()
int	IntegerUniform (int max)
int	IntegerUniform (int min, int max)
void	Integers (size_t count, std::vector< int > *integers)
void	IntegersUniform (size_t count, int min, int max, std::vector< int > *integers)
double	Double ()
double	DoubleUniform (double min, double max)
double	DoubleGaussian (double mean, double stddev)
void	Doubles (size_t count, std::vector< double > *doubles)
void	DoublesUniform (size_t count, double min, double max, std::vector< double > *doubles)
void	DoublesGaussian (size_t count, double mean, double stddev, std::vector< double > *doubles)

Static Public Member Functions
static unsigned long	Seed ()

Detailed Description

Definition at line 52 of file random_generator.h.

Constructor & Destructor Documentation

bsfm::math::RandomGenerator::RandomGenerator ( unsigned long  seed )

explicit

Definition at line 43 of file random_generator.cpp.

                                                   {
  srand(seed);
}

Member Function Documentation

double bsfm::math::RandomGenerator::Double

(

)

Definition at line 109 of file random_generator.cpp.

                               {
  return static_cast<double>(Integer()) / static_cast<double>(RAND_MAX);
}

double bsfm::math::RandomGenerator::DoubleGaussian	(	double	mean,
		double	stddev
	)

Definition at line 125 of file random_generator.cpp.

                                                                 {
  // Use the box-muller transform to approximate a normal distribution:
  // https://en.wikipedia.org/wiki/Box%E2%80%93Muller_transform
  // u must be \in (0, 1], and v must be \in [0, 1).
  double u = 1.0 - Double();
  double v = Double();
  double z = sqrt(-2.0 * log(u)) * cos(2.0 * M_PI * v);

  return mean + stddev * z;
}

void bsfm::math::RandomGenerator::Doubles	(	size_t	count,
		std::vector< double > *	doubles
	)

Definition at line 136 of file random_generator.cpp.

                                                                      {
  if (doubles == nullptr) {
    return;
  }

  for (size_t i = 0; i < count; ++i) {
    doubles->push_back(Double());
  }
}

void bsfm::math::RandomGenerator::DoublesGaussian	(	size_t	count,
		double	mean,
		double	stddev,
		std::vector< double > *	doubles
	)

Definition at line 157 of file random_generator.cpp.

                                                                  {
  if (doubles == nullptr) {
    return;
  }

  for (size_t i = 0; i < count; ++i) {
    doubles->push_back(DoubleGaussian(mean, stddev));
  }
}

void bsfm::math::RandomGenerator::DoublesUniform	(	size_t	count,
		double	min,
		double	max,
		std::vector< double > *	doubles
	)

Definition at line 146 of file random_generator.cpp.

                                                                 {
  if (doubles == nullptr) {
    return;
  }

  for (size_t i = 0; i < count; ++i) {
    doubles->push_back(DoubleUniform(min, max));
  }
}

double bsfm::math::RandomGenerator::DoubleUniform	(	double	min,
		double	max
	)

Definition at line 113 of file random_generator.cpp.

                                                            {
    if (min >= max) {
      LOG(WARNING) << "min >= max. Returning min.";
      // Eat a random number anyways and return min.
      Integer();
      return min;
    }

    double coefficient = (max - min) / static_cast<double>(RAND_MAX);
    return min + static_cast<double>(Integer()) * coefficient;
}

int bsfm::math::RandomGenerator::Integer

(

)

Definition at line 60 of file random_generator.cpp.

                             {
  // TODO(eanelson: Use a threadsafe rng.
  return rand();
}

void bsfm::math::RandomGenerator::Integers	(	size_t	count,
		std::vector< int > *	integers
	)

Definition at line 88 of file random_generator.cpp.

                                                                     {
  if (integers == nullptr) {
    return;
  }

  for (size_t i = 0; i < count; ++i) {
    integers->push_back(Integer());
  }
}

void bsfm::math::RandomGenerator::IntegersUniform	(	size_t	count,
		int	min,
		int	max,
		std::vector< int > *	integers
	)

Definition at line 98 of file random_generator.cpp.

                                                                {
  if (integers == nullptr) {
    return;
  }

  for (size_t i = 0; i < count; ++i) {
    integers->push_back(IntegerUniform(min, max));
  }
}

int bsfm::math::RandomGenerator::IntegerUniform

(

int

max

)

Definition at line 66 of file random_generator.cpp.

                                           {
  if (max <= 0) {
    LOG(WARNING) << "max <= 0. Returning 0.";
    // Eat a random number anyways and return 0.
    Integer();
    return 0;
  }

  return Integer() % static_cast<int>(max + 1);
}

int bsfm::math::RandomGenerator::IntegerUniform	(	int	min,
		int	max
	)

Definition at line 77 of file random_generator.cpp.

                                                    {
  if (min >= max) {
    LOG(WARNING) << "min >= max. Returning min.";
    // Eat a random number anyways and return min.
    Integer();
    return min;
  }

  return min + (Integer() % static_cast<int>(max - min + 1));
}

unsigned long bsfm::math::RandomGenerator::Seed ( )

static

Definition at line 47 of file random_generator.cpp.

                                    {
  // Hash from: http://burtleburtle.net/bob/hash/doobs.html
  // TODO(eanelson): Update this to read a seed from /dev/urandom instead.
  unsigned long a = clock();
  unsigned long b = time(NULL);
  unsigned long c = getpid();
  a-=b; a-=c; a^=(c >> 13); b-=c; b-=a; b^=(a << 8); c-=a; c-=b; c^=(b >> 13);
  a-=b; a-=c; a^=(c >> 12); b-=c; b-=a; b^=(a << 16); c-=a; c-=b; c^=(b >> 5);
  a-=b; a-=c; a^=(c >> 3); b-=c; b-=a; b^=(a << 10); c-=a; c-=b; c^=(b >> 15);
  return c;
}

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

• /Users/eanelson/Git/berkeley_sfm/src/cpp/math/random_generator.h
• /Users/eanelson/Git/berkeley_sfm/src/cpp/math/random_generator.cpp