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// $Id: G4NeutronHPWattSpectrum.hh,v 1.11 2006/06/29 20:49:39 gunter Exp $
// GEANT4 tag $Name: geant4-09-03 $
//
#ifndef G4NeutronHPWattSpectrum_h
#define G4NeutronHPWattSpectrum_h 1

#include "globals.hh"
#include "G4NeutronHPVector.hh"
#include "Randomize.hh"
#include "G4ios.hh"
#include <fstream>
#include "G4VNeutronHPEDis.hh"

// we will need a List of these .... one per term.

class G4NeutronHPWattSpectrum : public G4VNeutronHPEDis
{
  public:
  G4NeutronHPWattSpectrum()
  {
    expm1 = std::exp(-1.);
  }
  ~G4NeutronHPWattSpectrum()
  {
  }
  
  inline void Init(std::ifstream & aDataFile)
  {
    theFractionalProb.Init(aDataFile, eV);
    theApar.Init(aDataFile, eV);
    theBpar.Init(aDataFile, eV);
  }
  
  inline G4double GetFractionalProbability(G4double anEnergy)
  {
    return theFractionalProb.GetY(anEnergy);
  }
  
  G4double Sample(G4double anEnergy);
  
  private:
  
  inline G4double Watt(G4double anEnergy, G4double a, G4double b)
  {
    G4double energy = anEnergy/eV;
    G4double result = std::exp(-energy/a)*std::sinh(std::sqrt(b*energy));
    return result;
  }
  
  private:
  
  G4double expm1;
  
  G4NeutronHPVector theFractionalProb;
  
  G4NeutronHPVector theApar;
  G4NeutronHPVector theBpar;
  
};

#endif
