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  1. #include <iostream>
  2. #include <cstdlib>
  3. #include <ctime>
  4. #include <cmath>
  5.  
  6. #include "PoissonRandom.h"
  7.  
  8. using namespace std;
  9.  
  10. // simulation de v.a.r. uniforme sur ]0,1[ :
  11. inline double unif_rand() {
  12.     return (rand() + 0.5)/(RAND_MAX + 1.0);
  13. }
  14.  
  15. class Alea {
  16.  public:
  17.     virtual double rand() const = 0;
  18. };
  19.  
  20. class AleaDiscret : public Alea {
  21.  public:
  22.     virtual double loi(int n) const = 0;
  23.     virtual double rand() const;
  24. };
  25.  
  26. double AleaDiscret::rand() const {
  27.     double y = unif_rand();
  28.     int x = 0;
  29.     double Fx = loi(0);
  30.     while ( y > Fx ) {
  31.         Fx += loi(++x);
  32.     }
  33.     return double(x);
  34. }
  35.  
  36. class Poisson : public AleaDiscret {
  37.     double lambda;
  38.  
  39.     double e_lbda;
  40.  public :
  41.     Poisson(double l = 1.0) : lambda(l) , e_lbda(exp(-l)) {}
  42.     virtual double loi(int n) const {
  43.         return e_lbda*pow(lambda,n)/tgamma(n+1);
  44.     }
  45.  
  46.   // plus rapide que AleaDiscret::rand()
  47.     virtual double rand() const;
  48. };
  49.  
  50. double Poisson::rand() const {
  51.     double x = 1;
  52.     int n = -1;
  53.     do {
  54.         x *= unif_rand();
  55.         ++n;
  56.     } while ( x > e_lbda );
  57.     return double(n);
  58. }
  59.  
  60. double moy(const Alea & a) {
  61.     const int N = 1000;
  62.     double s = 0.0;
  63.     for (int n = 0 ; n < N ; ++n)
  64.         s += a.rand();
  65.     return s/N;
  66. }
  67.  
  68. void PoissonRandom(int durationNum, int poiNum, int totalNum) {
  69.     double total=0;
  70.     // double duration[100];
  71.     double *duration = new double[durationNum];
  72.     int tmp=0, num;
  73.     // Poisson poi(12);
  74.     Poisson poi(poiNum);
  75.     srand(int(time(0)));
  76.     do{
  77.         duration[tmp]=poi.rand();
  78.         total+=duration[tmp];
  79.         tmp++;
  80.     // }while(total<=50);
  81.     }while(total<=totalNum);
  82.  
  83.     for(int i=1; i<tmp; i++){
  84.         duration[i]+=duration[i-1];
  85.     }
  86.     cout<<tmp<<endl;
  87.     for(int i=0; i<tmp; i++){
  88.         cout<<duration[i]<<endl;
  89.     }
  90.     delete[] duration;
  91. }
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https://ideone.com/ySiZH
language:
C++ (gcc 8.3)
created:
13 years ago
visibility:
public

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