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random.hpp
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random.hpp
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/* This software is distributed under BSD 3-clause license (see LICENSE file).
*
* Copyright (c) 2012-2013 Sergey Lisitsyn
*/
#ifndef TAPKEE_DEFINES_RANDOM_H_
#define TAPKEE_DEFINES_RANDOM_H_
#include <cstdlib>
#include <algorithm>
#include <limits>
#include <random>
namespace tapkee
{
inline IndexType uniform_random_index()
{
#ifdef CUSTOM_UNIFORM_RANDOM_INDEX_FUNCTION
return CUSTOM_UNIFORM_RANDOM_INDEX_FUNCTION % std::numeric_limits<IndexType>::max();
#else
return std::rand();
#endif
}
inline IndexType uniform_random_index_bounded(IndexType upper)
{
return uniform_random_index() % upper;
}
inline ScalarType uniform_random()
{
#ifdef CUSTOM_UNIFORM_RANDOM_FUNCTION
return CUSTOM_UNIFORM_RANDOM_FUNCTION;
#else
return std::rand()/((double)RAND_MAX+1);
#endif
}
inline ScalarType gaussian_random()
{
#ifdef CUSTOM_GAUSSIAN_RANDOM_FUNCTION
return CUSTOM_GAUSSIAN_RANDOM_FUNCTION;
#else
ScalarType x, y, radius;
do {
x = 2*(std::rand()/((double)RAND_MAX+1)) - 1;
y = 2*(std::rand()/((double)RAND_MAX+1)) - 1;
radius = (x * x) + (y * y);
} while ((radius >= 1.0) || (radius == 0.0));
radius = std::sqrt(-2 * std::log(radius) / radius);
x *= radius;
y *= radius;
return x;
#endif
}
template <class RAI>
inline void random_shuffle(RAI first, RAI last)
{
std::random_device rng;
std::mt19937 urng(rng());
std::shuffle(first,last, urng);
}
}
#endif