Import Geant4 0.1.0 source tree

source/global/HEPRandom/include/G4Poisson.hh

@@ -0,0 +1,62 @@
+// This code implementation is the intellectual property of
+// the GEANT4 collaboration.
+//
+// By copying, distributing or modifying the Program (or any work
+// based on the Program) you indicate your acceptance of this statement,
+// and all its terms.
+//
+// $Id: G4Poisson.hh,v 1.2 1999/05/11 19:43:11 gcosmo Exp $
+// GEANT4 tag $Name: geant4-00-01 $
+//
+// 
+// ------------------------------------------------------------
+//      GEANT 4 class header file 
+//
+//      For information related to this code contact:
+//      CERN, IT Division, ASD group
+//
+// ------------------------------------------------------------
+// Description:
+// -----------
+// G4Poisson is the C++ implementation of the CERNLIB GPOISS algorithm
+// for the generation of Gaussian distributed random numbers. It has been
+// adapted to invoke HepRandom from CLHEP for the primary engine generators.
+// GPOISS is recognized to be a faster algorithm, providing however a less
+// accurate output, than the algorithm adopted in CLHEP.
+// ------------------------------------------------------------
+#ifndef G4POISSON_HH
+#define G4POISSON_HH
+
+#include "globals.hh"
+#include "Randomize.hh"
+
+G4long G4Poisson(G4double mean)
+{
+  G4long number = 0;
+  const G4int border = 16;
+  G4double limit = 2e9;
+
+  if(mean <= border) {
+    G4double position = RandFlat::shoot();
+    G4double poissonValue = exp(-mean);
+    G4double poissonSum = poissonValue;
+
+    while(poissonSum <= position) {
+      number++ ;
+      poissonValue *= mean/number;
+      poissonSum += poissonValue;
+    }
+    return number;
+  } // the case of mean <= 16
+
+  G4double value, t, y;
+  t = sqrt(-2*log(RandFlat::shoot()));
+  y = twopi*RandFlat::shoot();
+  t *= cos(y);
+  value = mean + t*sqrt(mean);
+  if(value <= 0) {return 0;}
+  if(value >= limit) { return G4long(limit);}
+  return G4long(value);
+}
+
+#endif  /* G4POISSON_HH */

source/global/HEPRandom/include/Randomize.hh

@@ -5,8 +5,8 @@
 // based on the Program) you indicate your acceptance of this statement,
 // and all its terms.
 //
-// $Id: Randomize.hh,v 2.1 1998/09/23 23:11:15 gcosmo Exp $
-// GEANT4 tag $Name: geant4-00 $
+// $Id: Randomize.hh,v 1.1 1999/01/07 16:08:58 gunter Exp $
+// GEANT4 tag $Name: geant4-00-01 $
 //
 #ifndef randomize_h
 #define randomize_h 1