AtlasFieldMap.icc

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/*
  Copyright (C) 2002-2021 CERN for the benefit of the ATLAS collaboration
*/
 
namespace MagField {
inline const BFieldZone*
MagField::AtlasFieldMap::findBFieldZone(double z, double r, double phi) const
{
 
  // make sure it's inside the largest zone
  // NB: the sign of the logic is chosen in order to return 0 on NaN inputs
  if (z >= m_zmin && z <= m_zmax && r <= m_rmax) {
    // find the edges of the zone
    // z
    int iz = int(m_invq[0] * (z - m_zmin)); // index to LUT
    iz = m_edgeLUT[0][iz];                  // tentative index from LUT
    if (z > m_edge[0][iz + 1]) {
      iz++;
    }
    // r
    int ir = int(m_invq[1] * r); // index to LUT - note minimum r is always 0
    ir = m_edgeLUT[1][ir];       // tentative index from LUT
    if (r > m_edge[1][ir + 1]) {
      ir++;
    }
    // phi
    int iphi =
      int(m_invq[2] * (phi + M_PI)); // index to LUT - minimum phi is -pi
    iphi = m_edgeLUT[2][iphi];       // tentative index from LUT
    if (phi > m_edge[2][iphi + 1]) {
      iphi++;
    }
    // use LUT to get the zone
    return m_zoneLUT[(iz * m_nr + ir) * m_nphi + iphi];
  }
  return nullptr;
}
 
// fast 2d map (made of one zone)
inline const BFieldMeshZR*
AtlasFieldMap::getBFieldMesh() const
{
  return m_meshZR;
}
 
}