CollinearFitAtTM2 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
double	chi2 () const
	chi2 More...
	CollinearFitAtTM2 (const TrajectoryMeasurement &tm)
	CollinearFitAtTM2 (const AlgebraicVector5 &fwdParameters, const AlgebraicSymMatrix55 &fwdCovariance, const AlgebraicVector5 &bwdParameters, const AlgebraicSymMatrix55 &bwdCovariance, const LocalPoint &hitPosition, const LocalError &hitErrors)
const ResultMatrix &	covariance () const
	covariance matrix of fitted parameters More...
Measurement1D	deltaP () const
	estimated deltaP (out-in) from fit parameters More...
int	ndof () const
	degrees of freedom More...
const ResultVector &	parameters () const
	vector of fitted parameters More...
bool	valid () const
	status of the fit More...

Private Member Functions
bool	fit (const AlgebraicVector5 &fwdParameters, const AlgebraicSymMatrix55 &fwdCovariance, const AlgebraicVector5 &bwdParameters, const AlgebraicSymMatrix55 &bwdCovariance, const LocalPoint &hitPosition, const LocalError &hitErrors)
	Perform the fit. Return value "true" for success. More...
void	initJacobian ()
	initialise the jacobian More...

Private Attributes
double	chi2_
ResultMatrix	covariance_
ROOT::Math::SMatrix< double, 12, 6 >	jacobian_
ROOT::Math::SVector< double, 12 >	measurements_
int	ndof_
ResultVector	parameters_
ROOT::Math::SVector< double, 6 >	projectedMeasurements_
bool	valid_
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 18 of file CollinearFitAtTM.h.

Member Typedef Documentation

typedef ROOT::Math::SMatrix<double,6,6,ROOT::Math::MatRepSym<double,6> > CollinearFitAtTM2::ResultMatrix

Definition at line 32 of file CollinearFitAtTM.h.

typedef ROOT::Math::SVector<double,6> CollinearFitAtTM2::ResultVector

Definition at line 31 of file CollinearFitAtTM.h.

Member Enumeration Documentation

anonymous enum

parameter indices in the result vector / covariance matrix

Enumerator
ParQpIn
ParQpOut
ParDxDz
ParDyDz
ParX
ParY

Definition at line 21 of file CollinearFitAtTM.h.

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

Constructor & Destructor Documentation

CollinearFitAtTM2::CollinearFitAtTM2

(

const TrajectoryMeasurement &

tm

)

Definition at line 4 of file CollinearFitAtTM.cc.

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

                                                                     : 
  valid_(false),chi2_(-1),ndof_(-1) {
  //
  // check input
  //
  if ( !tm.forwardPredictedState().isValid() ||
       !tm.backwardPredictedState().isValid() ||
       !tm.updatedState().isValid() ) {
    edm::LogWarning("CollinearFitAtTM2") << "Invalid state in TrajectoryMeasurement";
    return;
  }
  //
  // prepare fit
  //
  initJacobian();
  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();
  }

  fit(fwdPar,fwdCov,bwdPar,bwdCov,hitPos,hitErr);
}

CollinearFitAtTM2::CollinearFitAtTM2	(	const AlgebraicVector5 &	fwdParameters,
		const AlgebraicSymMatrix55 &	fwdCovariance,
		const AlgebraicVector5 &	bwdParameters,
		const AlgebraicSymMatrix55 &	bwdCovariance,
		const LocalPoint &	hitPosition,
		const LocalError &	hitErrors
	)

Definition at line 34 of file CollinearFitAtTM.cc.

References fit(), and initJacobian().

                                                 : 
  valid_(false),chi2_(-1),ndof_(-1) {
  //
  // prepare fit
  //
  initJacobian();

  fit(fwdParameters,fwdCovariance,bwdParameters,bwdCovariance,hitPosition,hitErrors);
}

Member Function Documentation

double CollinearFitAtTM2::chi2 ( void  ) const

inline

chi2

Definition at line 36 of file CollinearFitAtTM.h.

References chi2_.

{return chi2_;}

const ResultMatrix& CollinearFitAtTM2::covariance ( void  ) const

inline

covariance matrix of fitted parameters

Definition at line 42 of file CollinearFitAtTM.h.

References covariance_.

{return covariance_;}

Measurement1D CollinearFitAtTM2::deltaP

(

)

const

estimated deltaP (out-in) from fit parameters

Definition at line 131 of file CollinearFitAtTM.cc.

References covariance_, parameters_, mathSSE::sqrt(), and valid_.

Referenced by GsfTrackProducerBase::computeModeAtTM().

                                 {
  //
  // check validity
  //
  if ( !valid_ )  return Measurement1D();
  //
  // deltaP = 1/qpout - 1/qpin ; uncertainty from linear error propagation
  //
  double qpIn = parameters_(0);
  double sig2In = covariance_(0,0);
  double qpOut = parameters_(1);
  double sig2Out = covariance_(1,1);
  double corrInOut = covariance_(0,1);
  double pIn = 1./fabs(qpIn);
  double pOut = 1./fabs(qpOut);
  double sig2DeltaP = pIn/qpIn*pIn/qpIn*sig2In - 2*pIn/qpIn*pOut/qpOut*corrInOut + 
    pOut/qpOut*pOut/qpOut*sig2Out;

  return Measurement1D(pOut-pIn,sig2DeltaP?sqrt(sig2DeltaP):0.);
}

bool CollinearFitAtTM2::fit ( const AlgebraicVector5 &  fwdParameters, const AlgebraicSymMatrix55 &  fwdCovariance, const AlgebraicVector5 &  bwdParameters, const AlgebraicSymMatrix55 &  bwdCovariance, const LocalPoint &  hitPosition, const LocalError &  hitErrors  )

private

Perform the fit. Return value "true" for success.

Definition at line 66 of file CollinearFitAtTM.cc.

References chi2_, covariance_, i, j, jacobian_, measurements_, ndof_, parameters_, ParX, ParY, projectedMeasurements_, valid_, weightMatrix_, PV3DBase< T, PVType, FrameType >::x(), LocalError::xx(), LocalError::xy(), PV3DBase< T, PVType, FrameType >::y(), and LocalError::yy().

Referenced by CollinearFitAtTM2().

{

  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("CollinearFitAtTM2") << "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("CollinearFitAtTM2") << "Inversion of resulting weight matrix failed";
    return false;
  }

  parameters_ = covariance_*projectedMeasurements_;

  //
  // chi2
  //
  chi2_ = ROOT::Math::Similarity(measurements_,weightMatrix_) -
    ROOT::Math::Similarity(projectedMeasurements_,covariance_);
  ndof_ =  hitErr.xx()>0 ? 6 : 4;

  valid_ = true;
  return true;
}

void CollinearFitAtTM2::initJacobian ( )

private

initialise the jacobian

Definition at line 50 of file CollinearFitAtTM.cc.

References i, j, jacobian_, ParQpIn, and ParQpOut.

Referenced by CollinearFitAtTM2().

{
  //
  // 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.;
}

int CollinearFitAtTM2::ndof ( ) const

inline

degrees of freedom

Definition at line 38 of file CollinearFitAtTM.h.

References ndof_.

{return ndof_;}

const ResultVector& CollinearFitAtTM2::parameters ( void  ) const

inline

vector of fitted parameters

Definition at line 40 of file CollinearFitAtTM.h.

References parameters_.

{return parameters_;}

bool CollinearFitAtTM2::valid ( ) const

inline

status of the fit

Definition at line 34 of file CollinearFitAtTM.h.

References valid_.

{return valid_;}

Member Data Documentation

double CollinearFitAtTM2::chi2_

private

Definition at line 66 of file CollinearFitAtTM.h.

Referenced by chi2(), and fit().

ResultMatrix CollinearFitAtTM2::covariance_

private

Definition at line 65 of file CollinearFitAtTM.h.

Referenced by covariance(), deltaP(), and fit().

ROOT::Math::SMatrix<double,12,6> CollinearFitAtTM2::jacobian_

private

Definition at line 57 of file CollinearFitAtTM.h.

Referenced by fit(), and initJacobian().

ROOT::Math::SVector<double,12> CollinearFitAtTM2::measurements_

private

Definition at line 58 of file CollinearFitAtTM.h.

Referenced by fit().

int CollinearFitAtTM2::ndof_

private

Definition at line 67 of file CollinearFitAtTM.h.

Referenced by fit(), and ndof().

ResultVector CollinearFitAtTM2::parameters_

private

Definition at line 64 of file CollinearFitAtTM.h.

Referenced by Mixins._TypedParameterizable::clone(), Types.PSet::clone(), Mixins._TypedParameterizable::copy(), deltaP(), fit(), and parameters().

ROOT::Math::SVector<double,6> CollinearFitAtTM2::projectedMeasurements_

private

Definition at line 60 of file CollinearFitAtTM.h.

Referenced by fit().

bool CollinearFitAtTM2::valid_

private

Definition at line 63 of file CollinearFitAtTM.h.

Referenced by deltaP(), fit(), and valid().

ROOT::Math::SMatrix<double,12,12,ROOT::Math::MatRepSym<double,12> > CollinearFitAtTM2::weightMatrix_

private

Definition at line 59 of file CollinearFitAtTM.h.

Referenced by fit().