GsfBetheHeitlerUpdator.h

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#ifndef GsfBetheHeitlerUpdator_h_
#define GsfBetheHeitlerUpdator_h_

#include "TrackingTools/GsfTracking/interface/GsfMaterialEffectsUpdator.h"

#include "DataFormats/Math/interface/approx_exp.h"
#include "DataFormats/Math/interface/approx_log.h"

#include <iosfwd>
#include <string>

class GsfBetheHeitlerUpdator final : public GsfMaterialEffectsUpdator {
private:
  static constexpr int MaxSize = 6;
  static constexpr int MaxOrder = 6;

  class Polynomial {
  public:
    Polynomial() {}
    Polynomial(float coefficients[], int is) : m_size(is) {
      for (int i = 0; i != m_size; ++i)
        theCoeffs[i] = coefficients[i];
    }
    float operator()(float x) const {
      float sum = theCoeffs[0];
      for (int i = 1; i != m_size; ++i)
        sum = x * sum + theCoeffs[i];
      return sum;
    }

  private:
    float theCoeffs[MaxOrder] = {0};
    int m_size = 0;
  };

public:
  enum CorrectionFlag { NoCorrection = 0, MeanCorrection = 1, FullCorrection = 2 };

public:
  GsfBetheHeitlerUpdator *clone() const override { return new GsfBetheHeitlerUpdator(*this); }

public:
  GsfBetheHeitlerUpdator(const std::string fileName, const int correctionFlag);

private:
  struct GSContainer {
    float *first, *second, *third;
  };

  void compute(const TrajectoryStateOnSurface &, const PropagationDirection, Effect[]) const override;

private:
  void readParameters(const std::string);
  Polynomial readPolynomial(std::ifstream &, const unsigned int);

  void getMixtureParameters(const float, GSContainer &) const;
  void correctWeights(GSContainer &) const;
  float correctedFirstMean(const float, const GSContainer &) const;
  float correctedFirstVar(const float, const GSContainer &) const;

private:
  int theNrComponents;        
  int theTransformationCode;  
  int theCorrectionFlag;      

  Polynomial thePolyWeights[MaxSize];  
  Polynomial thePolyMeans[MaxSize];    
  Polynomial thePolyVars[MaxSize];     
};

#endif