GsfVertexWeightCalculator Class Reference

#include <GsfVertexWeightCalculator.h>

List of all members.

Public Types
typedef ReferenceCountingPointer < LinearizedTrackState< 5 > >	RefCountedLinearizedTrackState
Public Member Functions
double	calculate (const VertexState &oldVertex, const RefCountedLinearizedTrackState track, double cov) const
Private Types
typedef LinearizedTrackState < 5 >::AlgebraicMatrixN3	AlgebraicMatrixN3
typedef LinearizedTrackState < 5 >::AlgebraicMatrixNM	AlgebraicMatrixNM
typedef LinearizedTrackState < 5 >::AlgebraicSymMatrixNN	AlgebraicSymMatrixNN
typedef LinearizedTrackState < 5 >::AlgebraicVectorN	AlgebraicVectorN

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Detailed Description

Calulates the (non-normalised) weight of a component the new mixture of vertices for the Gaussian Sum vertex filter. (c.f. Th.Speer & R. Fruewirth, Comp.Phys.Comm 174, 935 (2006) )

Definition at line 14 of file GsfVertexWeightCalculator.h.

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Member Typedef Documentation

typedef LinearizedTrackState<5>::AlgebraicMatrixN3 GsfVertexWeightCalculator::AlgebraicMatrixN3 [private]

Definition at line 31 of file GsfVertexWeightCalculator.h.

typedef LinearizedTrackState<5>::AlgebraicMatrixNM GsfVertexWeightCalculator::AlgebraicMatrixNM [private]

Definition at line 32 of file GsfVertexWeightCalculator.h.

typedef LinearizedTrackState<5>::AlgebraicSymMatrixNN GsfVertexWeightCalculator::AlgebraicSymMatrixNN [private]

Definition at line 33 of file GsfVertexWeightCalculator.h.

typedef LinearizedTrackState<5>::AlgebraicVectorN GsfVertexWeightCalculator::AlgebraicVectorN [private]

Definition at line 30 of file GsfVertexWeightCalculator.h.

typedef ReferenceCountingPointer<LinearizedTrackState<5> > GsfVertexWeightCalculator::RefCountedLinearizedTrackState

Definition at line 18 of file GsfVertexWeightCalculator.h.

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Member Function Documentation

double GsfVertexWeightCalculator::calculate	(	const VertexState &	oldVertex,
		const RefCountedLinearizedTrackState	track,
		double	cov
	)		const

Method to calculate the weight A negative weight is returned in case of error.

Definition at line 6 of file GsfVertexWeightCalculator.cc.

References a, b, diffTreeTool::diff, VertexState::error(), funct::exp(), edm::detail::isnan(), M_PI, GlobalErrorBase< T, ErrorWeightType >::matrix_new(), VertexState::position(), funct::pow(), mathSSE::sqrt(), CommonMethods::weight(), VertexState::weightInMixture(), PV3DBase< T, PVType, FrameType >::x(), PV3DBase< T, PVType, FrameType >::y(), and PV3DBase< T, PVType, FrameType >::z().

Referenced by GsfVertexUpdator::createNewComponent(), and GsfVertexSmoother::createNewComponent().

{
  double previousWeight = oldVertex.weightInMixture() * track->weightInMixture();
  // Jacobians
  const AlgebraicMatrixN3 & a = track->positionJacobian();
  const AlgebraicMatrixNM & b = track->momentumJacobian();

  //track information
  AlgebraicVectorN trackParameters = track->predictedStateParameters();
  AlgebraicSymMatrixNN trackParametersError = track->predictedStateError();
  //vertex information
  AlgebraicSymMatrix33 oldVertexError  = oldVertex.error().matrix_new();
  //Vertex position
  GlobalPoint oldVertexPosition = oldVertex.position();
  AlgebraicVector3 oldVertexCoord;
  oldVertexCoord[0] = oldVertexPosition.x();
  oldVertexCoord[1] = oldVertexPosition.y();
  oldVertexCoord[2] = oldVertexPosition.z();

  // prior momentum information
  AlgebraicVector3 priorMomentum = track->predictedStateMomentumParameters();

  AlgebraicSymMatrix33 priorMomentumCov;
  priorMomentumCov(0,0) = 1.0E-9;
  priorMomentumCov(1,1) = 1.0E-6;
  priorMomentumCov(2,2) = 1.0E-6;
  priorMomentumCov *= cov;

  AlgebraicVectorN diff = trackParameters - track->constantTerm() -
    a*oldVertexCoord -b*priorMomentum;
  track->checkParameters(diff);
  AlgebraicSymMatrixNN sigmaM = trackParametersError +
        ROOT::Math::Similarity(a,oldVertexError) +
        ROOT::Math::Similarity(b,priorMomentumCov);

  double sigmaDet;
  sigmaM.Det(sigmaDet);
  int  ifail = ! sigmaM.Invert(); 
  if(ifail != 0) {
    edm::LogWarning("GsfVertexWeightCalculator") << "S matrix inversion failed";
    return -1.;
  }
  
        
  double chi = ROOT::Math::Similarity(diff,sigmaM);;  //SigmaM is now inverted !!!
  double weight = pow(2. * M_PI, -0.5 * 5) * sqrt(1./sigmaDet) * exp(-0.5 * chi);

  if (std::isnan(weight) || sigmaDet<=0.) {
    edm::LogWarning("GsfVertexWeightCalculator") << "Weight is NaN";
    return -1.;
  }

  return weight*previousWeight;

}