Visual Servoing Platform  version 3.1.0
vpUniRand.cpp
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30  *
31  * Description:
32  * Generation of random number with uniform and normal probability density.
33  *
34  * Authors:
35  * Eric Marchand
36  *
37  *****************************************************************************/
38 
39 #include <math.h>
40 #include <visp3/core/vpUniRand.h>
41 
47 inline void vpUniRand::draw0()
48 {
49  long k = x / q; // temp value for computing without overflow
50  x = a * (x - k * q) - k * r;
51  if (x < 0)
52  x += m; // compute x without overflow
53 }
54 
63 {
64  const long ntab = 33; // we work on a 32 elements array.
65  // the 33rd one is actually the first value of y.
66  const long modulo = ntab - 2;
67 
68  static long y = 0;
69  static long T[ntab];
70 
71  long j; // index of T
72 
73  // step 0
74  if (!y) { // first time
75  for (j = 0; j < ntab; j++) {
76  draw0();
77  T[j] = x;
78  } // compute table T
79  y = T[ntab - 1];
80  }
81 
82  // step 1
83  j = y & modulo; // compute modulo ntab+1 (the first element is the 0th)
84 
85  // step 3
86  y = T[j];
87  double ans = (double)y / normalizer;
88 
89  // step 4
90  // generate x(k+i) and set y=x(k+i)
91  draw0();
92 
93  // refresh T[j];
94  T[j] = x;
95 
96  return ans;
97 }
double draw1()
Definition: vpUniRand.cpp:62
long x
Definition: vpUniRand.h:78