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