WaveformErfcFunctor.h

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/*
 * WaveformErfcFunctor.h
 *
 *  Created on: Jun 9, 2017
 *      Author: Hovanes Egiyan
 */

#ifndef LIBRARIES_TAC_WAVEFORMERFCFUNCTOR_H_
#define LIBRARIES_TAC_WAVEFORMERFCFUNCTOR_H_

#include <math.h>

#include <iostream>
#include <string>
#include <functional>

#include <TMath.h>

class WaveformErfcFunctor {
public:
   WaveformErfcFunctor() {
   }
   virtual ~WaveformErfcFunctor() {
   }
   static std::string getTagString() {
      return "ERFC";
   }
   double operator()(const double* xArray, const double* pArray) {
      static const double zeroTolerance = 1.0e-25;
      double x = xArray[0];
      double pedestal = pArray[0];
      double peakPoint = pArray[1];
      double riseTime = pArray[2];

      double expAmpl = pArray[3];
      double expLambda = pArray[4];

      double sigma = riseTime / 2.0 ;
//    if (lineSlope > zeroTolerance)
//       sigma = expAmpl / lineSlope;
      double mu = 0;
      if (expLambda > zeroTolerance)
         mu = 1. / expLambda;

      double value = 0;

      if (sigma > zeroTolerance) {
         double variablePart = expAmpl * exp(-mu * (x - peakPoint))
               * TMath::Erfc(
                     (mu * sigma * sigma - (x - peakPoint))
                           / (sqrt(2) * sigma));
         if (variablePart < 0)
            variablePart = 0;
         value = pedestal + variablePart;
      }
      return value;
   }
};

#endif /* LIBRARIES_TAC_WAVEFORMERFCFUNCTOR_H_ */