From: Yann Duplouy <yann.duplouy@inria.fr>
Date: Mon, 21 Oct 2019 09:41:50 +0000 (+0200)
Subject: Adding the normal distribution
X-Git-Tag: v3.25~386^2~9
X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/commitdiff_plain/65e50c050d9856bf4728824596bf75d9b3b0ab6e

Adding the normal distribution
---

diff --git a/include/xbt/random.hpp b/include/xbt/random.hpp
index 84e8182a36..cf2b168c18 100644
--- a/include/xbt/random.hpp
+++ b/include/xbt/random.hpp
@@ -14,6 +14,7 @@ namespace random {
 int uniform_int(int, int);
 double uniform_real(double, double);
 double exponential(double);
+double normal(double, double);
 } // namespace random
 } // namespace xbt
 } // namespace simgrid
diff --git a/src/xbt/random.cpp b/src/xbt/random.cpp
index 95aed12a15..7f8af6affb 100644
--- a/src/xbt/random.cpp
+++ b/src/xbt/random.cpp
@@ -46,6 +46,15 @@ double exponential(double lambda)
   return -1 / lambda * log(numerator / divisor);
 }
 
+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 z0                = sqrt(-2.0 * log(numeratorA / divisor)) * cos(2 * M_PI * numeratorB / divisor);
+  return z0 * sd + mean;
+}
+
 } // namespace random
 } // namespace xbt
 } // namespace simgrid