* src/misc/random.hh (nrand, bmrand, prand): New functions.

(barand): New class.
* src/misc/random.cc (nrand, bmrand, prand): New functions.
* wrap/python/spot.i: Process src/misc/random.hh.

src/misc/random.cc

@@ -57,4 +57,82 @@ namespace spot
     return min + static_cast<int>((max - min + 1) * drand());
   }
 
+  double
+  nrand()
+  {
+    const double r = drand();
+
+    const double lim = 1.e-20;
+    if (r < lim)
+      return -1./lim;
+    if (r > 1.0 - lim)
+      return 1./lim;
+
+    double t;
+    if (r < 0.5)
+      t = sqrt(-2.0 * log(r));
+    else
+      t = sqrt(-2.0 * log(1.0 - r));
+
+    const double p0 = 0.322232431088;
+    const double p1 = 1.0;
+    const double p2 = 0.342242088547;
+    const double p3 = 0.204231210245e-1;
+    const double p4 = 0.453642210148e-4;
+    const double q0 = 0.099348462606;
+    const double q1 = 0.588581570495;
+    const double q2 = 0.531103462366;
+    const double q3 = 0.103537752850;
+    const double q4 = 0.385607006340e-2;
+    const double p = p0 + t * (p1 + t * (p2 + t * (p3 + t * p4)));
+    const double q = q0 + t * (q1 + t * (q2 + t * (q3 + t * q4)));
+
+    if (r < 0.5)
+      return (p / q) - t;
+    else
+      return t - (p / q);
+  }
+
+  double
+  bmrand()
+  {
+    static double next;
+    static bool has_next = false;
+
+    if (has_next)
+      {
+	has_next = false;
+	return next;
+      }
+
+    double x;
+    double y;
+    double r;
+    do
+      {
+	x = 2.0 * drand() - 1.0;
+	y = 2.0 * drand() - 1.0;
+	r = x * x + y * y;
+      }
+    while (r >= 1.0 || r == 0.0);
+    r = sqrt(-2 * log(r) / r);
+    next = y * r;
+    has_next = true;
+    return x * r;
+  }
+
+  int
+  prand(double p)
+  {
+    double s = 0.0;
+    long x = 0;
+
+    while (s < p)
+      {
+	s -= log(1.0 - drand());
+	++x;
+      }
+    return x - 1;
+  }
+
 }