1bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant//===----------------------------------------------------------------------===// 2bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant// 3f5256e16dfc425c1d466f6308d4026d529ce9e0bHoward Hinnant// The LLVM Compiler Infrastructure 4bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant// 5b64f8b07c104c6cc986570ac8ee0ed16a9f23976Howard Hinnant// This file is dual licensed under the MIT and the University of Illinois Open 6b64f8b07c104c6cc986570ac8ee0ed16a9f23976Howard Hinnant// Source Licenses. See LICENSE.TXT for details. 7bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant// 8bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant//===----------------------------------------------------------------------===// 9bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant 10bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant// <random> 11bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant 12bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant// template<class _IntType = int> 13bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant// class uniform_int_distribution 14bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant 15bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant// template<class _URNG> result_type operator()(_URNG& g, const param_type& parm); 16bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant 17bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant#include <random> 18bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant#include <cassert> 19df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant#include <vector> 20df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant#include <numeric> 21df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant 22df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnanttemplate <class T> 23df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnantinline 24df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard HinnantT 25df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnantsqr(T x) 26df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant{ 27df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant return x * x; 28df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant} 29bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant 30bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnantint main() 31bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant{ 32bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant { 33bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant typedef std::uniform_int_distribution<> D; 34df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant typedef std::minstd_rand G; 35bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant typedef D::param_type P; 36bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant G g; 37df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant D d(5, 100); 38bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant P p(-10, 20); 39df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant const int N = 100000; 40df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant std::vector<D::result_type> u; 41df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant for (int i = 0; i < N; ++i) 42df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant { 43df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant D::result_type v = d(g, p); 44df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant assert(p.a() <= v && v <= p.b()); 45df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant u.push_back(v); 46df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant } 47df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant double mean = std::accumulate(u.begin(), u.end(), 48df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant double(0)) / u.size(); 49df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant double var = 0; 50df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant double skew = 0; 51df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant double kurtosis = 0; 52df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant for (int i = 0; i < u.size(); ++i) 53bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant { 54df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant double d = (u[i] - mean); 55df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant double d2 = sqr(d); 56df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant var += d2; 57df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant skew += d * d2; 58df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant kurtosis += d2 * d2; 59bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant } 60df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant var /= u.size(); 61df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant double dev = std::sqrt(var); 62df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant skew /= u.size() * dev * var; 63df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant kurtosis /= u.size() * var * var; 64df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant kurtosis -= 3; 65df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant double x_mean = ((double)p.a() + p.b()) / 2; 66df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant double x_var = (sqr((double)p.b() - p.a() + 1) - 1) / 12; 67df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant double x_skew = 0; 68df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant double x_kurtosis = -6. * (sqr((double)p.b() - p.a() + 1) + 1) / 69df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant (5. * (sqr((double)p.b() - p.a() + 1) - 1)); 70d6d1171f2c3f254582ae1d5b9e14cea0ea8e701bHoward Hinnant assert(std::abs((mean - x_mean) / x_mean) < 0.01); 71d6d1171f2c3f254582ae1d5b9e14cea0ea8e701bHoward Hinnant assert(std::abs((var - x_var) / x_var) < 0.01); 72df40dc6c1a8ca0bf00fb6aec030f69042f61d974Howard Hinnant assert(std::abs(skew - x_skew) < 0.01); 73d6d1171f2c3f254582ae1d5b9e14cea0ea8e701bHoward Hinnant assert(std::abs((kurtosis - x_kurtosis) / x_kurtosis) < 0.01); 74bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant } 75bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant} 76