CDCDedxWidgetSigma.h

/**************************************************************************
 * basf2 (Belle II Analysis Software Framework)                           *
 * Author: The Belle II Collaboration                                     *
 *                                                                        *
 * See git log for contributors and copyright holders.                    *
 * This file is licensed under LGPL-3.0, see LICENSE.md.                  *
 **************************************************************************/
 
#pragma once
 
#include <math.h>
 
namespace Belle2 {
  class CDCDedxWidgetSigma {
 
  public:
 
    CDCDedxWidgetSigma() {};
 
    virtual ~CDCDedxWidgetSigma() {};
 
    double sigmaCurve(double* x, const std::vector<double>& par) const
    {
 
      double f = 0;
 
      if (par[0] == 1) { // return dedx parameterization
        if (par.size() == 3)
          f = par[1] + par[2] * x[0];
      }
 
      else if (par[0] == 2) { // return nhit or sin(theta) parameterization
        if (par.size() == 6)
          f = par[1] * std::pow(x[0], 4) + par[2] * std::pow(x[0], 3) +
              par[3] * x[0] * x[0] + par[4] * x[0] + par[5];
      }
 
      else if (par[0] == 3) { // return cos(theta) parameterization
        if (par.size() == 11)
          f = par[1] * exp(-0.5 * pow(((x[0] - par[2]) / par[3]), 2)) +
              par[4] * pow(x[0], 6) + par[5] * pow(x[0], 5) + par[6] * pow(x[0], 4) +
              par[7] * pow(x[0], 3) + par[8] * x[0] * x[0] + par[9] * x[0] + par[10];
      }
 
      return f;
    }
  };
}  // Belle2 namespace