MathiesonOriginal.cxx

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// Copyright 2019-2020 CERN and copyright holders of ALICE O2.
// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
// All rights not expressly granted are reserved.
//
// This software is distributed under the terms of the GNU General Public
// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
//
// In applying this license CERN does not waive the privileges and immunities
// granted to it by virtue of its status as an Intergovernmental Organization
// or submit itself to any jurisdiction.
 
 
#include "MCHBase/MathiesonOriginal.h"
 
#include <TMath.h>
 
namespace o2
{
namespace mch
{
 
//_________________________________________________________________________________________________
void MathiesonOriginal::setSqrtKx3AndDeriveKx2Kx4(float sqrtKx3)
{
  mSqrtKx3 = sqrtKx3;
  mKx2 = TMath::Pi() / 2. * (1. - 0.5 * mSqrtKx3);
  float cx1 = mKx2 * mSqrtKx3 / 4. / TMath::ATan(static_cast<double>(mSqrtKx3));
  mKx4 = cx1 / mKx2 / mSqrtKx3;
}
 
//_________________________________________________________________________________________________
void MathiesonOriginal::setSqrtKy3AndDeriveKy2Ky4(float sqrtKy3)
{
  mSqrtKy3 = sqrtKy3;
  mKy2 = TMath::Pi() / 2. * (1. - 0.5 * mSqrtKy3);
  float cy1 = mKy2 * mSqrtKy3 / 4. / TMath::ATan(static_cast<double>(mSqrtKy3));
  mKy4 = cy1 / mKy2 / mSqrtKy3;
}
 
//_________________________________________________________________________________________________
float MathiesonOriginal::integrate(float xMin, float yMin, float xMax, float yMax) const
{
 
  xMin *= mInversePitch;
  xMax *= mInversePitch;
  yMin *= mInversePitch;
  yMax *= mInversePitch;
  //
  // The Mathieson function
  double uxMin = mSqrtKx3 * TMath::TanH(mKx2 * xMin);
  double uxMax = mSqrtKx3 * TMath::TanH(mKx2 * xMax);
 
  double uyMin = mSqrtKy3 * TMath::TanH(mKy2 * yMin);
  double uyMax = mSqrtKy3 * TMath::TanH(mKy2 * yMax);
 
  return static_cast<float>(4. * mKx4 * (TMath::ATan(uxMax) - TMath::ATan(uxMin)) *
                            mKy4 * (TMath::ATan(uyMax) - TMath::ATan(uyMin)));
}
 
} // namespace mch
} // namespace o2