d6d1171f2c
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@104224 91177308-0d34-0410-b5e6-96231b3b80d8
141 lines
4.1 KiB
C++
141 lines
4.1 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// <random>
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// template<class RealType = double>
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// class student_t_distribution
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// template<class _URNG> result_type operator()(_URNG& g);
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#include <random>
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#include <cassert>
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#include <vector>
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#include <numeric>
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template <class T>
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inline
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T
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sqr(T x)
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{
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return x * x;
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}
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int main()
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{
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{
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typedef std::student_t_distribution<> D;
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typedef D::param_type P;
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typedef std::minstd_rand G;
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G g;
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D d(5.5);
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const int N = 1000000;
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std::vector<D::result_type> u;
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for (int i = 0; i < N; ++i)
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u.push_back(d(g));
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double mean = std::accumulate(u.begin(), u.end(), 0.0) / u.size();
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double var = 0;
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double skew = 0;
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double kurtosis = 0;
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for (int i = 0; i < u.size(); ++i)
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{
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double d = (u[i] - mean);
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double d2 = sqr(d);
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var += d2;
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skew += d * d2;
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kurtosis += d2 * d2;
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}
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var /= u.size();
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double dev = std::sqrt(var);
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skew /= u.size() * dev * var;
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kurtosis /= u.size() * var * var;
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kurtosis -= 3;
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double x_mean = 0;
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double x_var = d.n() / (d.n() - 2);
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double x_skew = 0;
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double x_kurtosis = 6 / (d.n() - 4);
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assert(std::abs(mean - x_mean) < 0.01);
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assert(std::abs((var - x_var) / x_var) < 0.01);
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assert(std::abs(skew - x_skew) < 0.01);
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assert(std::abs((kurtosis - x_kurtosis) / x_kurtosis) < 0.2);
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}
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{
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typedef std::student_t_distribution<> D;
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typedef D::param_type P;
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typedef std::minstd_rand G;
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G g;
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D d(10);
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const int N = 1000000;
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std::vector<D::result_type> u;
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for (int i = 0; i < N; ++i)
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u.push_back(d(g));
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double mean = std::accumulate(u.begin(), u.end(), 0.0) / u.size();
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double var = 0;
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double skew = 0;
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double kurtosis = 0;
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for (int i = 0; i < u.size(); ++i)
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{
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double d = (u[i] - mean);
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double d2 = sqr(d);
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var += d2;
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skew += d * d2;
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kurtosis += d2 * d2;
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}
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var /= u.size();
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double dev = std::sqrt(var);
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skew /= u.size() * dev * var;
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kurtosis /= u.size() * var * var;
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kurtosis -= 3;
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double x_mean = 0;
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double x_var = d.n() / (d.n() - 2);
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double x_skew = 0;
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double x_kurtosis = 6 / (d.n() - 4);
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assert(std::abs(mean - x_mean) < 0.01);
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assert(std::abs((var - x_var) / x_var) < 0.01);
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assert(std::abs(skew - x_skew) < 0.01);
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assert(std::abs((kurtosis - x_kurtosis) / x_kurtosis) < 0.04);
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}
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{
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typedef std::student_t_distribution<> D;
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typedef D::param_type P;
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typedef std::minstd_rand G;
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G g;
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D d(100);
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const int N = 1000000;
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std::vector<D::result_type> u;
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for (int i = 0; i < N; ++i)
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u.push_back(d(g));
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double mean = std::accumulate(u.begin(), u.end(), 0.0) / u.size();
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double var = 0;
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double skew = 0;
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double kurtosis = 0;
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for (int i = 0; i < u.size(); ++i)
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{
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double d = (u[i] - mean);
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double d2 = sqr(d);
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var += d2;
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skew += d * d2;
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kurtosis += d2 * d2;
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}
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var /= u.size();
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double dev = std::sqrt(var);
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skew /= u.size() * dev * var;
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kurtosis /= u.size() * var * var;
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kurtosis -= 3;
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double x_mean = 0;
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double x_var = d.n() / (d.n() - 2);
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double x_skew = 0;
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double x_kurtosis = 6 / (d.n() - 4);
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assert(std::abs(mean - x_mean) < 0.01);
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assert(std::abs((var - x_var) / x_var) < 0.01);
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assert(std::abs(skew - x_skew) < 0.01);
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assert(std::abs((kurtosis - x_kurtosis) / x_kurtosis) < 0.02);
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}
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}
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