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//
//
//
// Author:  Vladimir Ivanchenko (Vladimir.Ivantchenko@cern.ch)
//
// History:
// -----------
// 27 May 2002   VI        Created
//
// -------------------------------------------------------------------

#include "G4LinLogInterpolation.hh"

// Constructor

G4LinLogInterpolation::G4LinLogInterpolation()
{ }


// Destructor

G4LinLogInterpolation::~G4LinLogInterpolation()
{ }


G4double G4LinLogInterpolation::Calculate(G4double x, G4int bin, 
					  const G4DataVector& points, 
					  const G4DataVector& data) const
{
  //G4cout << "G4LinLogInterpolation is performed on dataset (2 arguments) " << G4endl;
  G4int nBins = data.size() - 1;
  G4double value = 0.;
  if (x < points[0])
    {
      value = 0.;
    }
  else if (bin < nBins)
    {
      G4double e1 = points[bin];
      G4double e2 = points[bin+1];
      G4double d1 = std::log(data[bin]);
      G4double d2 = std::log(data[bin+1]);
      value = std::exp(d1 + (d2 - d1)*(x - e1)/ (e2 - e1));
    }
  else
    {
      value = data[nBins];
    }
  return value;
}

G4double G4LinLogInterpolation::Calculate(G4double x, G4int bin, 
					  const G4DataVector& points,
                                          const G4DataVector& data,
                                          const G4DataVector& /*log_points*/, 
					  const G4DataVector& log_data) const
{
  //G4cout << "G4LinLogInterpolation is performed on dataset (4 arguments) " << G4endl;
  G4int nBins = data.size() - 1;
  G4double value = 0.;
  //G4double log_x = std::log10(x);
  if (x < points[0])
    {
      value = 0.;
    }
  else if (bin < nBins)
    {
      G4double e1 = points[bin];
      G4double e2 = points[bin+1];
      G4double d1 = data[bin];
      G4double d2 = data[bin+1];
      //G4double log_e1 = log_points[bin];
      //G4double log_e2 = log_points[bin+1];
      G4double log_d1 = log_data[bin];
      G4double log_d2 = log_data[bin+1];
      if (d1 > 0.0 && d2 > 0.0)
        {
// Values e1, e2, d1 and d2 are the log values of the corresponding
// original energy and data values. Simple linear interpolation performed
// on loagarithmic data should be equivalent to log-log interpolation
          //value = log_d1 + (log_d2 - log_d1)*(log_x - log_e1)/(log_e2 - log_e1);
          value = std::exp(log_d1 + (log_d2 - log_d1)*(x - e1)/(e2 - e1));
        }
      else
        {
          if (d1 == 0.0) log_d1 = -300;
          if (d2 == 0.0) log_d2 = -300;
          value = std::exp(log_d1 + (log_d2 - log_d1)*(x - e1)/(e2 - e1));
        }
   }
 else
   {
     value = data[nBins];
   }
  return value;
}