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white_gaussian.hh
1 // Copyright (C) 2010 EPITA Research and Development Laboratory (LRDE)
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25 
26 #ifndef MLN_FUN_N2V_WHITE_GAUSSIAN_HH
27 # define MLN_FUN_N2V_WHITE_GAUSSIAN_HH
28 
32 
33 # include <cstdlib>
34 # include <ctime>
35 
36 # include <mln/core/concept/function.hh>
37 # include <mln/math/sqrt.hh>
38 
39 
40 namespace mln
41 {
42 
43  namespace fun
44  {
45 
46  namespace n2v
47  {
48 
55  template <typename V>
56  struct white_gaussian : Function_n2v< white_gaussian<V> >
57  {
58  typedef V result;
59 
60  white_gaussian(double sigma_);
61  V operator()() const;
62 
63  double sigma;
64  };
65 
66 
67 # ifndef MLN_INCLUDE_ONLY
68 
69 
70  template <typename V>
72  : sigma(sigma_)
73  {
74  srand(time(0));
75  }
76 
77 
78  template <typename V>
80  {
81  double X = 0;
82  for (int i = 1; i < 50; ++i)
83  {
84  double U = rand() / (float)RAND_MAX;
85  X = X + U;
86  }
87 
88  X = X - 25.f; /* set mean to 0 */
89  X = X * math::sqrt(12 / 50.f); /* adjust variance to 1 */
90 
91  return sigma * X;
92  };
93 
94 
95 # endif // ! MLN_INCLUDE_ONLY
96 
97  } // end of namespace mln::fun::n2v
98 
99  } // end of namespace mln::fun
100 
101 } // end of namespace mln
102 
103 
104 #endif // ! MLN_FUN_N2V_WHITE_GAUSSIAN_HH