made distribution a member variable

Processes/Pythia/Random.cc

@@ -12,9 +12,6 @@
 
 namespace corsika::process::pythia {
 
-  double Random::flat() {
-    std::uniform_real_distribution<double> dist;
-    return dist(fRNG);
-  }
+  double Random::flat() { return fDist(fRNG); }
 
 } // namespace corsika::process::pythia

Processes/Pythia/Random.h

@@ -23,6 +23,7 @@ namespace corsika::process {
       double flat();
 
     private:
+      std::uniform_real_distribution<double> fDist;
       corsika::random::RNG& fRNG =
           corsika::random::RNGManager::GetInstance().GetRandomStream("pythia");
     };