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); 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(a, b); 38 const int N = 1000000; 39 std::vector<D::result_type> u; 40 for (int i = 0; i < N; ++i) 41 u.push_back(d(g)); 42 std::sort(u.begin(), u.end()); 43 for (int i = 0; i < N; ++i) 44 assert(std::abs(f(u[i], a, b) - double(i)/N) < .001); 45 } 46 { 47 typedef std::cauchy_distribution<> D; 48 typedef D::param_type P; 49 typedef std::mt19937 G; 50 G g; 51 const double a = -1.5; 52 const double b = 1; 53 D d(a, b); 54 const int N = 1000000; 55 std::vector<D::result_type> u; 56 for (int i = 0; i < N; ++i) 57 u.push_back(d(g)); 58 std::sort(u.begin(), u.end()); 59 for (int i = 0; i < N; ++i) 60 assert(std::abs(f(u[i], a, b) - double(i)/N) < .001); 61 } 62 { 63 typedef std::cauchy_distribution<> D; 64 typedef D::param_type P; 65 typedef std::mt19937 G; 66 G g; 67 const double a = .5; 68 const double b = 2; 69 D d(a, b); 70 const int N = 1000000; 71 std::vector<D::result_type> u; 72 for (int i = 0; i < N; ++i) 73 u.push_back(d(g)); 74 std::sort(u.begin(), u.end()); 75 for (int i = 0; i < N; ++i) 76 assert(std::abs(f(u[i], a, b) - double(i)/N) < .001); 77 } 78 } 79
