CollinearFitAtTM Class Reference

#include <CollinearFitAtTM.h>

Public Types
enum	{   ParQpIn = 0, ParQpOut, ParDxDz, ParDyDz,   ParX, ParY }
	parameter indices in the result vector / covariance matrix More...
typedef ROOT::Math::SMatrix< double, 6, 6, ROOT::Math::MatRepSym< double, 6 > >	ResultMatrix
typedef ROOT::Math::SVector< double, 6 >	ResultVector

Public Member Functions
	CollinearFitAtTM ()
bool	fit (const AlgebraicVector5 &fwdParameters, const AlgebraicSymMatrix55 &fwdCovariance, const AlgebraicVector5 &bwdParameters, const AlgebraicSymMatrix55 &bwdCovariance, const LocalPoint &hitPosition, const LocalError &hitErrors, ResultVector &parameters, ResultMatrix &covariance, double &chi2)
	Fit with explicit input parameters. Return value "true" for success. More...
bool	fit (const TrajectoryMeasurement &tm, ResultVector &parameters, ResultMatrix &covariance, double &chi2)
	Fit for one TM. Return value "true" for success. More...

Private Attributes
ROOT::Math::SMatrix< double, 12, 6 >	jacobian_
ROOT::Math::SVector< double, 12 >	measurements_
ROOT::Math::SVector< double, 6 >	projectedMeasurements_
ROOT::Math::SMatrix< double, 12, 12, ROOT::Math::MatRepSym< double, 12 > >	weightMatrix_

Detailed Description

Constrained fit at a TrajectoryMeasurement assuming collinearity of incoming / outgoing momenta. The result of the fit is a vector of 6 variables: the first five correspond to local trajectory parameters for the incoming momentum, the 6th is the estimated remaining energy fraction (p_out / p_in). The NDF are 6 (4) for a valid (invalid) RecHit.

Definition at line 17 of file CollinearFitAtTM.h.

Member Typedef Documentation

ResultMatrix

typedef ROOT::Math::SMatrix<double, 6, 6, ROOT::Math::MatRepSym<double, 6> > CollinearFitAtTM::ResultMatrix

Definition at line 25 of file CollinearFitAtTM.h.

ResultVector

typedef ROOT::Math::SVector<double, 6> CollinearFitAtTM::ResultVector

Definition at line 24 of file CollinearFitAtTM.h.

Member Enumeration Documentation

anonymous enum

anonymous enum

parameter indices in the result vector / covariance matrix

Enumerator
ParQpIn
ParQpOut
ParDxDz
ParDyDz
ParX
ParY

Definition at line 20 of file CollinearFitAtTM.h.

{ ParQpIn = 0, ParQpOut, ParDxDz, ParDyDz, ParX, ParY };

Constructor & Destructor Documentation

CollinearFitAtTM()

CollinearFitAtTM::CollinearFitAtTM

(

)

Definition at line 4 of file CollinearFitAtTM.cc.

                                   {
  //
  // Jacobian
  //
  for (int i = 0; i < 12; ++i) {
    for (int j = 0; j < 6; ++j)
      jacobian_(i, j) = 0;
  }
  for (int i = 1; i < 5; ++i) {
    jacobian_(i, ParQpOut + i) = jacobian_(i + 5, ParQpOut + i) = 1;
  }
  jacobian_(0, ParQpIn) = 1.;
  jacobian_(5, ParQpOut) = 1.;
}

References mps_fire::i, dqmiolumiharvest::j, jacobian_, ParQpIn, and ParQpOut.

Member Function Documentation

fit() [1/2]

bool CollinearFitAtTM::fit	(	const AlgebraicVector5 &	fwdParameters,
		const AlgebraicSymMatrix55 &	fwdCovariance,
		const AlgebraicVector5 &	bwdParameters,
		const AlgebraicSymMatrix55 &	bwdCovariance,
		const LocalPoint &	hitPosition,
		const LocalError &	hitErrors,
		ResultVector &	parameters,
		ResultMatrix &	covariance,
		double &	chi2
	)

Fit with explicit input parameters. Return value "true" for success.

Definition at line 48 of file CollinearFitAtTM.cc.

                                         {
  if (hitErr.xx() > 0)
    jacobian_(10, ParX) = jacobian_(11, ParY) = 1;
  else
    jacobian_(10, ParX) = jacobian_(11, ParY) = 0;
 
  for (int i = 0; i < 12; ++i) {
    for (int j = 0; j < 12; ++j)
      weightMatrix_(i, j) = 0;
  }
 
  for (int i = 0; i < 5; ++i)
    measurements_(i) = fwdParameters(i);
  weightMatrix_.Place_at(fwdCovariance, 0, 0);
  for (int i = 0; i < 5; ++i)
    measurements_(i + 5) = bwdParameters(i);
  weightMatrix_.Place_at(bwdCovariance, 5, 5);
  if (hitErr.xx() > 0) {
    measurements_(10) = hitPos.x();
    measurements_(11) = hitPos.y();
    weightMatrix_(10, 10) = hitErr.xx();
    weightMatrix_(10, 11) = weightMatrix_(11, 10) = hitErr.xy();
    weightMatrix_(11, 11) = hitErr.yy();
  } else {
    measurements_(10) = measurements_(11) = 0.;
    weightMatrix_(10, 10) = weightMatrix_(11, 11) = 1.;
    weightMatrix_(10, 11) = weightMatrix_(11, 10) = 0.;
  }
  //
  // invert covariance matrix
  //
  if (!weightMatrix_.Invert()) {
    edm::LogWarning("CollinearFitAtTM") << "Inversion of input covariance matrix failed";
    return false;
  }
 
  //
  projectedMeasurements_ = ROOT::Math::Transpose(jacobian_) * (weightMatrix_ * measurements_);
  //
  // Fitted parameters and covariance matrix
  //
  covariance = ROOT::Math::SimilarityT(jacobian_, weightMatrix_);
  if (!covariance.Invert()) {
    edm::LogWarning("CollinearFitAtTM") << "Inversion of resulting weight matrix failed";
    return false;
  }
 
  parameters = covariance * projectedMeasurements_;
 
  //
  // chi2
  //
  chi2 =
      ROOT::Math::Similarity(measurements_, weightMatrix_) - ROOT::Math::Similarity(projectedMeasurements_, covariance);
 
  return true;
}

References hltPixelTracks_cff::chi2, mps_fire::i, dqmiolumiharvest::j, jacobian_, measurements_, ParX, ParY, projectedMeasurements_, weightMatrix_, PV3DBase< T, PVType, FrameType >::x(), LocalError::xx(), LocalError::xy(), PV3DBase< T, PVType, FrameType >::y(), and LocalError::yy().

Referenced by trackingPlots.Iteration::modules().

fit() [2/2]

bool CollinearFitAtTM::fit	(	const TrajectoryMeasurement &	tm,
		ResultVector &	parameters,
		ResultMatrix &	covariance,
		double &	chi2
	)

Fit for one TM. Return value "true" for success.

Definition at line 19 of file CollinearFitAtTM.cc.

                                         {
  //
  // check input
  //
  if (!tm.forwardPredictedState().isValid() || !tm.backwardPredictedState().isValid() || !tm.updatedState().isValid()) {
    edm::LogWarning("CollinearFitAtTM") << "Invalid state in TrajectoryMeasurement";
    return false;
  }
  //
  // prepare fit
  //
  AlgebraicVector5 fwdPar = tm.forwardPredictedState().localParameters().vector();
  AlgebraicSymMatrix55 fwdCov = tm.forwardPredictedState().localError().matrix();
  AlgebraicVector5 bwdPar = tm.backwardPredictedState().localParameters().vector();
  AlgebraicSymMatrix55 bwdCov = tm.backwardPredictedState().localError().matrix();
 
  LocalPoint hitPos(0., 0., 0.);
  LocalError hitErr(-1., -1., -1.);
  if (tm.recHit()->isValid()) {
    hitPos = tm.recHit()->localPosition();
    hitErr = tm.recHit()->localPositionError();
  }
 
  return fit(fwdPar, fwdCov, bwdPar, bwdCov, hitPos, hitErr, parameters, covariance, chi2);
}

References TrajectoryMeasurement::backwardPredictedState(), hltPixelTracks_cff::chi2, TrajectoryMeasurement::forwardPredictedState(), TrajectoryStateOnSurface::isValid(), TrajectoryStateOnSurface::localError(), TrajectoryStateOnSurface::localParameters(), LocalTrajectoryError::matrix(), TrajectoryMeasurement::recHit(), TrajectoryMeasurement::updatedState(), and LocalTrajectoryParameters::vector().

Referenced by trackingPlots.Iteration::modules(), and PFGsfHelper::PFGsfHelper().

Member Data Documentation

jacobian_

ROOT::Math::SMatrix<double, 12, 6> CollinearFitAtTM::jacobian_

private

Definition at line 40 of file CollinearFitAtTM.h.

Referenced by CollinearFitAtTM(), and fit().

measurements_

ROOT::Math::SVector<double, 12> CollinearFitAtTM::measurements_

private

Definition at line 41 of file CollinearFitAtTM.h.

Referenced by fit().

projectedMeasurements_

ROOT::Math::SVector<double, 6> CollinearFitAtTM::projectedMeasurements_

private

Definition at line 43 of file CollinearFitAtTM.h.

Referenced by fit().

weightMatrix_

ROOT::Math::SMatrix<double, 12, 12, ROOT::Math::MatRepSym<double, 12> > CollinearFitAtTM::weightMatrix_

private

Definition at line 42 of file CollinearFitAtTM.h.

Referenced by fit().