71 lines
1.5 KiB
C++
71 lines
1.5 KiB
C++
#include "sled/random.h"
|
|
#include <cmath>
|
|
|
|
namespace sled {
|
|
Random::Random(uint64_t seed) : state_(seed) {}
|
|
|
|
uint32_t
|
|
Random::Rand(uint32_t t) const
|
|
{
|
|
uint32_t x = NextOutput();
|
|
uint64_t result = x * (static_cast<uint64_t>(t) + 1);
|
|
result >>= 32;
|
|
return result;
|
|
}
|
|
|
|
uint32_t
|
|
Random::Rand(uint32_t low, uint32_t high) const
|
|
{
|
|
return Rand(high - low) + low;
|
|
}
|
|
|
|
int32_t
|
|
Random::Rand(int32_t low, int32_t high) const
|
|
{
|
|
const int64_t low_i64{low};
|
|
uint32_t range = static_cast<uint32_t>(high - low_i64);
|
|
return static_cast<int32_t>(Rand(range) + low_i64);
|
|
}
|
|
|
|
template<>
|
|
float
|
|
Random::Rand<float>() const
|
|
{
|
|
double result = NextOutput() - 1;
|
|
result = result / static_cast<double>(0xFFFFFFFFFFFFFFFFull);
|
|
return static_cast<float>(result);
|
|
}
|
|
|
|
template<>
|
|
double
|
|
Random::Rand<double>() const
|
|
{
|
|
double result = NextOutput() - 1;
|
|
result = result / static_cast<double>(0xFFFFFFFFFFFFFFFFull);
|
|
return result;
|
|
}
|
|
|
|
template<>
|
|
bool
|
|
Random::Rand<bool>() const
|
|
{
|
|
return Rand(0, 1) == 1;
|
|
}
|
|
|
|
double
|
|
Random::Gaussian(double mean, double standard_deviation) const
|
|
{
|
|
const double kPi = 3.14159265358979323846;
|
|
double u1 = static_cast<double>(NextOutput()) / static_cast<double>(0xFFFFFFFFFFFFFFFFull);
|
|
double u2 = static_cast<double>(NextOutput()) / static_cast<double>(0xFFFFFFFFFFFFFFFFull);
|
|
return mean + standard_deviation * sqrt(-2 * log(u1)) * cos(2 * kPi * u2);
|
|
}
|
|
|
|
double
|
|
Random::Exponential(double lambda) const
|
|
{
|
|
double uniform = Rand<double>();
|
|
return -log(uniform) / lambda;
|
|
}
|
|
}// namespace sled
|