1 //===----------------------------------------------------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is dual licensed under the MIT and the University of Illinois Open 6 // Source Licenses. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 // <random> 11 12 // template<class RealType = double> 13 // class cauchy_distribution 14 15 // template<class _URNG> result_type operator()(_URNG& g, const param_type& parm); 16 17 #include <random> 18 #include <cassert> 19 #include <vector> 20 #include <algorithm> 21 22 double 23 f(double x, double a, double b) 24 { 25 return 1/3.1415926535897932 * std::atan((x - a)/b) + .5; 26 } 27 28 int main() 29 { 30 { 31 typedef std::cauchy_distribution<> D; 32 typedef D::param_type P; 33 typedef std::mt19937 G; 34 G g; 35 const double a = 10; 36 const double b = .5; 37 D d; 38 P p(a, b); 39 const int N = 1000000; 40 std::vector<D::result_type> u; 41 for (int i = 0; i < N; ++i) 42 u.push_back(d(g, p)); 43 std::sort(u.begin(), u.end()); 44 for (int i = 0; i < N; ++i) 45 assert(std::abs(f(u[i], a, b) - double(i)/N) < .001); 46 } 47 { 48 typedef std::cauchy_distribution<> D; 49 typedef D::param_type P; 50 typedef std::mt19937 G; 51 G g; 52 const double a = -1.5; 53 const double b = 1; 54 D d; 55 P p(a, b); 56 const int N = 1000000; 57 std::vector<D::result_type> u; 58 for (int i = 0; i < N; ++i) 59 u.push_back(d(g, p)); 60 std::sort(u.begin(), u.end()); 61 for (int i = 0; i < N; ++i) 62 assert(std::abs(f(u[i], a, b) - double(i)/N) < .001); 63 } 64 { 65 typedef std::cauchy_distribution<> D; 66 typedef D::param_type P; 67 typedef std::mt19937 G; 68 G g; 69 const double a = .5; 70 const double b = 2; 71 D d; 72 P p(a, b); 73 const int N = 1000000; 74 std::vector<D::result_type> u; 75 for (int i = 0; i < N; ++i) 76 u.push_back(d(g, p)); 77 std::sort(u.begin(), u.end()); 78 for (int i = 0; i < N; ++i) 79 assert(std::abs(f(u[i], a, b) - double(i)/N) < .001); 80 } 81 } 82
