CombinedExtrapolatorTest.cxx

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/*
   Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
 */

// CombinedExtrapolatorTest.cxx, (c) ATLAS Detector software
 
// Tracking
#include "TrkExAlgs/CombinedExtrapolatorTest.h"
#include "TrkSurfaces/CylinderSurface.h"
#include "TrkSurfaces/DiscSurface.h"
#include "TrkSurfaces/PerigeeSurface.h"
#include "TrkGeometry/TrackingGeometry.h"
#include "TrkEventPrimitives/ParticleHypothesis.h"
 
//================ Constructor =================================================
Trk::CombinedExtrapolatorTest::CombinedExtrapolatorTest(const std::string& name, ISvcLocator* pSvcLocator)
  :
  AthAlgorithm(name, pSvcLocator) {}
 
//================ Destructor =================================================
 
Trk::CombinedExtrapolatorTest::~CombinedExtrapolatorTest() {
  delete m_gaussDist;
  delete m_flatDist;
}
 
//================ Initialisation =================================================
 
StatusCode Trk::CombinedExtrapolatorTest::initialize() {
  // Code entered here will be executed once at program start.
  msg(MSG::INFO) << " initialize()" << endmsg;
 
  // Get Extrapolator from ToolService
  if (m_extrapolator.retrieve().isFailure()) {
    msg(MSG::FATAL) << "Could not retrieve Tool " << m_extrapolator << ". Exiting." << endmsg;
    return StatusCode::FAILURE;
  }
 
  m_gaussDist = new Rndm::Numbers(randSvc(), Rndm::Gauss(0., 1.));
  m_flatDist = new Rndm::Numbers(randSvc(), Rndm::Flat(0., 1.));
 
  msg(MSG::INFO) << "initialize() successful in " << endmsg;
  return StatusCode::SUCCESS;
}
 
//================ Finalisation =================================================
 
StatusCode Trk::CombinedExtrapolatorTest::finalize() {
  // Code entered here will be executed once at the end of the program run.
  return StatusCode::SUCCESS;
}
 
//================ Execution ====================================================
 
StatusCode Trk::CombinedExtrapolatorTest::execute(const EventContext& ctx) {
  msg(MSG::INFO) << " execute()" << endmsg;
  // retrieve outer boundary
  if (!m_outerBoundary) {
    m_trackingGeometry = m_extrapolator->trackingGeometry();
    m_outerBoundary = m_trackingGeometry->highestTrackingVolume();
    if (!m_outerBoundary) {
      msg(MSG::FATAL) << "Could not retrieve geometry boundary  from " << m_extrapolator << ". Exiting." << endmsg;
      return StatusCode::FAILURE;
    }
    msg(MSG::INFO) << " boundary retrieved " << endmsg;
  }
 
  // generate with random number generator
  double d0 = m_gaussDist->shoot() * m_sigmaD0;
  double z0 = m_minZ0 + m_flatDist->shoot() * (m_maxZ0 - m_minZ0);
  double phi = 2. * M_PI * m_flatDist->shoot() - M_PI;
  double ctheta = -1. + 2 * m_flatDist->shoot();
  double theta = acos(ctheta);
  double p = m_minP + m_flatDist->shoot() * (m_maxP - m_minP);
  double charge = (m_flatDist->shoot() > 0.5) ? -1. : 1.;
  double qOverP = charge / (p);
 
  // the initial perigee with random numbers
  const Trk::PerigeeSurface perSurface;
  Trk::Perigee initialPerigee(d0, z0, phi, theta, qOverP, perSurface);
  // input covariance matrix
  const Trk::TrackParameters* seed = initialPerigee.clone();
 
  const Trk::PerigeeSurface& pSf = initialPerigee.associatedSurface();
 
  const Trk::TrackParameters* destParameters = m_extrapolator->extrapolateToVolume(
    ctx,
    *seed,
    *m_outerBoundary,
    Trk::alongMomentum,
    static_cast<Trk::ParticleHypothesis>(m_particleType.value())).release();
 
  if (!destParameters || !Trk::TrackingGeometry::atVolumeBoundary(destParameters->position(), m_outerBoundary, 0.001)) {
    msg(MSG::ERROR) << " extrapolation to outer boundary failed for input parameters: " <<
    initialPerigee.parameters() << endmsg;
  } else {
    // forward extrapolation ok
    msg(MSG::INFO) << " outer boundary reached at: " << destParameters->position().perp() << "," <<
    destParameters->position().z() << endmsg;
    msg(MSG::INFO) << "cov matrix:" << destParameters->covariance() << endmsg;
 
    const Trk::TrackParameters* peri = m_extrapolator->extrapolate(
      ctx,
      *destParameters,
      pSf,
      Trk::oppositeMomentum,
      false,
      static_cast<Trk::ParticleHypothesis>(m_particleType.value())).release();
    if (peri) {
      msg(MSG::INFO) << " extrapolation to perigee:input: " << initialPerigee.parameters() << endmsg;
      msg(MSG::INFO) << " extrapolation to perigee:output: " << peri->parameters() << endmsg;
      msg(MSG::INFO) << "cov matrix:" << peri->covariance() << endmsg;
    } else {
      msg(MSG::ERROR) << " extrapolation to perigee failed for input parameters: " << destParameters->parameters() <<
      endmsg;
    }
    delete peri;
  }
 
  delete destParameters;
 
  return StatusCode::SUCCESS;
}
 
//============================================================================================