double uniform_real(double, double);
double exponential(double);
double normal(double, double);
+void set_mersenne_seed(int);
} // namespace random
} // namespace xbt
} // namespace simgrid
double exponential(double lambda)
{
- unsigned long numerator = mt19937_gen() - mt19937_gen.min();
- unsigned long divisor = mt19937_gen.max() - mt19937_gen.min();
- return -1 / lambda * log(numerator / divisor);
+ return -1 / lambda * log(uniform_real(0, 1));
}
double normal(double mean, double sd)
{
- unsigned long numeratorA = mt19937_gen() - mt19937_gen.min();
- unsigned long numeratorB = mt19937_gen() - mt19937_gen.min();
- unsigned long divisor = mt19937_gen.max() - mt19937_gen.min();
- double u1 = numeratorA / divisor;
+ double u1 = 0;
while (u1 < std::numeric_limits<double>::min()) {
- numeratorA = mt19937_gen() - mt19937_gen.min();
- u1 = numeratorA / divisor;
+ u1 = uniform_real(0, 1);
}
- double z0 = sqrt(-2.0 * log(numeratorA / divisor)) * cos(2 * M_PI * numeratorB / divisor);
+ double u2 = uniform_real(0, 1);
+ double z0 = sqrt(-2.0 * log(u1)) * cos(2 * M_PI * u2);
return z0 * sd + mean;
}
+void set_mersenne_seed(int seed)
+{
+ mt19937_gen.seed(seed);
+}
+
} // namespace random
} // namespace xbt
} // namespace simgrid