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// Historic fragment from M.Komogorov; clean-up still necessary @@@
#include "G4ExcitedStringDecay.hh"
#include "G4KineticTrack.hh"

G4ExcitedStringDecay::G4ExcitedStringDecay()
{
	theStringDecay=NULL;
}

G4ExcitedStringDecay::G4ExcitedStringDecay(G4VLongitudinalStringDecay * aStringDecay)
: theStringDecay(aStringDecay)
{}

G4ExcitedStringDecay::G4ExcitedStringDecay(const G4ExcitedStringDecay &) : G4VStringFragmentation()
{
} 

G4ExcitedStringDecay::~G4ExcitedStringDecay()
{
}

const G4ExcitedStringDecay & G4ExcitedStringDecay::operator=(const G4ExcitedStringDecay &)
{
  throw G4HadronicException(__FILE__, __LINE__, "G4ExcitedStringDecay::operator= meant to not be accessable");
  return *this;
}

int G4ExcitedStringDecay::operator==(const G4ExcitedStringDecay &) const
{
  return 0;
}

int G4ExcitedStringDecay::operator!=(const G4ExcitedStringDecay &) const
{
  return 1;
}

G4bool G4ExcitedStringDecay::
EnergyAndMomentumCorrector(G4KineticTrackVector* Output, G4LorentzVector& TotalCollisionMom)   
  {
    const int    nAttemptScale = 500;
    const double ErrLimit = 1.E-5;
    if (Output->empty())
       return TRUE;
    G4LorentzVector SumMom;
    G4double        SumMass = 0;     
    G4double        TotalCollisionMass = TotalCollisionMom.m();
    if( !(TotalCollisionMass<1) && !(TotalCollisionMass>-1) )
    {
      std::cout << "TotalCollisionMomentum = "<<TotalCollisionMom<<G4endl;
      throw G4HadronicException(__FILE__, __LINE__, "G4ExcitedStringDecay received nan mass...");
    }
    // Calculate sum hadron 4-momenta and summing hadron mass
    unsigned int cHadron;
    for(cHadron = 0; cHadron < Output->size(); cHadron++)
    {
        SumMom  += Output->operator[](cHadron)->Get4Momentum();
	if( !(SumMom<1) && !(SumMom>-1) )
	{
          throw G4HadronicException(__FILE__, __LINE__, "G4ExcitedStringDecay::EnergyAndMomentumCorrector() received nan momentum...");
	}
        SumMass += Output->operator[](cHadron)->GetDefinition()->GetPDGMass();
	if( !(SumMass<1) && !(SumMass>-1) )
	{
          throw G4HadronicException(__FILE__, __LINE__, "G4ExcitedStringDecay::EnergyAndMomentumCorrector() received nan mass...");
	}
    }
    // Cannot correct a single particle
    if (Output->size() < 2) return FALSE;
    
    if (SumMass > TotalCollisionMass) return FALSE;
    SumMass = SumMom.m2();
    if (SumMass < 0) return FALSE;
    SumMass = std::sqrt(SumMass);

     // Compute c.m.s. hadron velocity and boost KTV to hadron c.m.s.
    G4ThreeVector Beta = -SumMom.boostVector();
    Output->Boost(Beta);

    // Scale total c.m.s. hadron energy (hadron system mass).
    // It should be equal interaction mass
    G4double Scale = 1;
    G4int cAttempt = 0;
    G4double Sum = 0;
    G4bool success = false;
    for(cAttempt = 0; cAttempt < nAttemptScale; cAttempt++)
    {
      Sum = 0;
      for(cHadron = 0; cHadron < Output->size(); cHadron++)
      {
        G4LorentzVector HadronMom = Output->operator[](cHadron)->Get4Momentum();
        HadronMom.setVect(Scale*HadronMom.vect());
        G4double E = std::sqrt(HadronMom.vect().mag2() + sqr(Output->operator[](cHadron)->GetDefinition()->GetPDGMass()));
        HadronMom.setE(E);
        Output->operator[](cHadron)->Set4Momentum(HadronMom);
        Sum += E;
      } 
      Scale = TotalCollisionMass/Sum;    
#ifdef debug_G4ExcitedStringDecay 
      G4cout << "Scale-1=" << Scale -1 
                << ",  TotalCollisionMass=" << TotalCollisionMass
		<< ",  Sum=" << Sum
		<< G4endl;
#endif     
      if (std::fabs(Scale - 1) <= ErrLimit) 
      {
        success = true;
	break;
      }
    }
    
    if(!success)
    {
      G4cout << "G4ExcitedStringDecay::EnergyAndMomentumCorrector - Warning"<<G4endl;
      G4cout << "   Scale not unity at end of iteration loop: "<<TotalCollisionMass<<" "<<Sum<<" "<<Scale<<G4endl;
      G4cout << "   Number of secondaries: " << Output->size() << G4endl;
      G4cout << "   Wanted total energy: " <<  TotalCollisionMom.e() << G4endl; 
      G4cout << "   Increase number of attempts or increase ERRLIMIT"<<G4endl;
//       throw G4HadronicException(__FILE__, __LINE__, "G4ExcitedStringDecay failed to correct...");
    }

    // Compute c.m.s. interaction velocity and KTV back boost   
    Beta = TotalCollisionMom.boostVector();
    Output->Boost(Beta);
    return success;
  }