SelectionVariableHelper.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
 
namespace Belle2 {
  template<class PointType, class DataType>
  struct SelVarHelper {
 
 
    static DataType s_MagneticFieldFactor; //  = 1.5 * 0.00299710;
 
 
    static void resetMagneticField(DataType magneticFieldStrength = 1.5) { SelVarHelper::s_MagneticFieldFactor = magneticFieldStrength * 0.00299710; }
 
 
    static DataType calcPerp2(const PointType& aHit)
    { return (aHit.X() * aHit.X() + aHit.Y() * aHit.Y()); }
 
 
    static DataType calcPerp(const PointType& aHit) { return sqrt(calcPerp2(aHit)); }
 
 
    static DataType calcMag2(const PointType& aHit)
    { return (aHit.X() * aHit.X() + aHit.Y() * aHit.Y() + aHit.Z() * aHit.Z()); }
 
 
    static DataType calcMag(const PointType& aHit) { return sqrt(calcMag2(aHit)); }
 
 
    static DataType calcDot(const PointType& aHit, const PointType& bHit)
    { return (aHit.X() * bHit.X() + aHit.Y() * bHit.Y() + aHit.Z() * bHit.Z()); }
 
    static DataType calcPt(DataType radius, DataType field = SelVarHelper::s_MagneticFieldFactor)
    {
      // TODO WARNING hardcoded value, is there a quasi-global value for such cases (this case, minimal accepted radius)
      // if (fabs(radius) < 0.0000001) { throw (Circle_too_small() << radius << 0.0000001); }
 
      //WARNING: does not care for negative radius!!
      return field * radius;
    } // return unit: GeV/c
 
  };
 
  template<typename PointType, typename DataType> DataType SelVarHelper<PointType, DataType>::s_MagneticFieldFactor = 1.5 *
      0.00299710;
 
}