iPatGlobalFitter.cxx

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/*
   Copyright (C) 2002-2026 CERN for the benefit of the ATLAS collaboration
 */

// iPatGlobalFitter.cxx
//   access full derivative and covariance matrices
//
// (c) ATLAS Detector software
 
#include "TrkiPatFitter/iPatGlobalFitter.h"
 
#include "GaudiKernel/SystemOfUnits.h"
#include "GaudiKernel/ThreadLocalContext.h"
#include "TrkiPatFitterUtils/ExtrapolationType.h"
#include "TrkiPatFitterUtils/FitMeasurement.h"
#include "TrkiPatFitterUtils/FitParameters.h"
#include "TrkiPatFitterUtils/FitProcedure.h"
 
namespace Trk {
 
Track* iPatGlobalFitter::alignmentFit(
    const EventContext& ctx,
    AlignmentCache& alignCache, const Track& trk,
    const RunOutlierRemoval runOutlier,
    const ParticleHypothesis matEffects) const {
  //  @TODO ensure the number of iterations is passed through to the fitter
  // setMinIterations (alignCache.m_minIterations);
  alignCache.m_derivMatrix.reset();
  alignCache.m_fullCovarianceMatrix.reset();
  alignCache.m_iterationsOfLastFit = 0;
 
  auto [refittedTrack, fitState] =
      fitWithState(ctx, trk, runOutlier, matEffects);
 
  if (refittedTrack) {
    alignCache.m_derivMatrix = derivMatrix(*fitState);
    alignCache.m_fullCovarianceMatrix = fullCovarianceMatrix(*fitState);
    alignCache.m_iterationsOfLastFit = iterationsOfLastFit(*fitState);
  }
  return refittedTrack.release();
}
 
std::unique_ptr<Amg::MatrixX> iPatGlobalFitter::derivMatrix(
    const FitState& fitState) const {
  // copy derivatives to a new HepMatrix
  if (!fitState.hasMeasurements() || !fitState.parameters) {
    return nullptr;
  }
 
  int numberParameters = 5;
  if (m_allParameters) {
    numberParameters = fitState.parameters->numberParameters();
  }
  int rows = 0;
 
  for (const FitMeasurement* m : fitState.getMeasurements()) {
    if (!m->isPositionMeasurement()) {
      continue;
    }
    rows += m->numberDoF();
  }
 
  if (!numberParameters || !rows) {
    return nullptr;
  }
 
  ATH_MSG_VERBOSE(" DerivMatrix : " << fitState.getMeasurements().size()
                                    << " measurement objects giving " << rows
                                    << " rows and " << numberParameters
                                    << " columns (parameters)");
 
  auto derivativeMatrix =
      std::make_unique<Amg::MatrixX>(rows, numberParameters);
  int row = 0;
  for (const FitMeasurement* m : fitState.getMeasurements()) {
    if (!m->numberDoF() || !m->isPositionMeasurement()) {
      continue;
    }
    double norm = 0.;
    if (m->weight() > 0.) {
      norm = 1. / m->weight();
    }
 
    for (int col = 0; col < numberParameters; ++col) {
      (*derivativeMatrix)(row, col) = norm * m->derivative(col);
    }
 
    // take care of units for momentum derivs
    (*derivativeMatrix)(row, 4) *= Gaudi::Units::TeV;
    if (fitState.parameters->fitEnergyDeposit()) {
      (*derivativeMatrix)(row, 5) *= Gaudi::Units::TeV;
    }
    ++row;
    if (m->numberDoF() < 2) {
      continue;
    }
 
    // pixel measurements
    norm = 0.;
    if (m->weight2() > 0.)
      norm = 1. / m->weight2();
    for (int col = 0; col < numberParameters; ++col) {
      (*derivativeMatrix)(row, col) = norm * m->derivative2(col);
    }
    (*derivativeMatrix)(row, 4) *= Gaudi::Units::TeV;
    if (fitState.parameters->fitEnergyDeposit()) {
      (*derivativeMatrix)(row, 5) *= Gaudi::Units::TeV;
    }
    ++row;
  }
 
  if (row != rows) {
    ATH_MSG_WARNING("iPatGlobalFitter: inconsistent #rows in deriv matrix ");
  }
 
  return derivativeMatrix;
}
 
std::unique_ptr<Amg::MatrixX> iPatGlobalFitter::fullCovarianceMatrix(
    const FitState& fitState) const {
  int numberParameters = 5;
 
  if (m_allParameters) {
    numberParameters = fitState.parameters->numberParameters();
  }
  ATH_MSG_VERBOSE(" FullCovarianceMatrix for " << numberParameters
                                               << " parameters");
 
  return std::make_unique<Amg::MatrixX>(Trk::FitProcedure::fullCovariance()->block(
      0, 0, numberParameters, numberParameters));
}
 
int iPatGlobalFitter::iterationsOfLastFit(const FitState& fitState) {
  return fitState.iterations;
}
 
void iPatGlobalFitter::setMinIterations(int minIterations) {
  m_fitProcedure->setMinIterations(minIterations);
}
}  // namespace Trk