VertexDistance3D Class Reference

#include <VertexDistance3D.h>

Inheritance diagram for VertexDistance3D:

List of all members.

Public Member Functions
virtual VertexDistance3D *	clone () const
virtual Measurement1D	signedDistance (const reco::Vertex &primVtx, const reco::Vertex &secVtx, const GlobalVector &momentum) const
	VertexDistance3D ()
Private Member Functions
virtual float	compatibility (const GlobalPoint &vtx1Position, const GlobalError &vtx1PositionError, const GlobalPoint &vtx2Position, const GlobalError &vtx2PositionError) const
virtual Measurement1D	distance (const GlobalPoint &vtx1Position, const GlobalError &vtx1PositionError, const GlobalPoint &vtx2Position, const GlobalError &vtx2PositionError) const
Private Attributes
AlgebraicSymMatrix33	theNullMatrix

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Detailed Description

Computes the distance and chi-squared compatibility between two vertices with their 3D positions.

Definition at line 13 of file VertexDistance3D.h.

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Constructor & Destructor Documentation

VertexDistance3D::VertexDistance3D

(

)

[inline]

Definition at line 18 of file VertexDistance3D.h.

Referenced by clone().

{}

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Member Function Documentation

virtual VertexDistance3D* VertexDistance3D::clone

(

void

)

const [inline, virtual]

Implements VertexDistance.

Definition at line 32 of file VertexDistance3D.h.

References VertexDistance3D().

  {
    return new VertexDistance3D(*this);
  }

float VertexDistance3D::compatibility	(	const GlobalPoint &	vtx1Position,
		const GlobalError &	vtx1PositionError,
		const GlobalPoint &	vtx2Position,
		const GlobalError &	vtx2PositionError
	)		const [private, virtual]

Implements VertexDistance.

Definition at line 47 of file VertexDistance3D.cc.

References diffTreeTool::diff, error, Exception, GlobalErrorBase< T, ErrorWeightType >::matrix(), PV3DBase< T, PVType, FrameType >::x(), PV3DBase< T, PVType, FrameType >::y(), and PV3DBase< T, PVType, FrameType >::z().

{
  // error matrix of residuals
  AlgebraicSymMatrix33 err1 = vtx1PositionError.matrix();
  AlgebraicSymMatrix33 err2 = vtx2PositionError.matrix();
  AlgebraicSymMatrix33 error = err1 + err2;
  if (error == theNullMatrix) return FLT_MAX;

  // position residuals
  GlobalVector diff = vtx2Position - vtx1Position;
  AlgebraicVector3 vDiff;
  vDiff[0] = diff.x();
  vDiff[1] = diff.y();
  vDiff[2] = diff.z();

  // Invert error matrix of residuals
  bool ifail = !error.InvertChol();
  if (ifail) {
    throw cms::Exception("VertexDistance3D::matrix inversion problem");
  }

  return ROOT::Math::Similarity(error,vDiff);
}

Measurement1D VertexDistance3D::distance	(	const GlobalPoint &	vtx1Position,
		const GlobalError &	vtx1PositionError,
		const GlobalPoint &	vtx2Position,
		const GlobalError &	vtx2PositionError
	)		const [private, virtual]

Implements VertexDistance.

Definition at line 22 of file VertexDistance3D.cc.

References diffTreeTool::diff, error, PV3DBase< T, PVType, FrameType >::mag(), GlobalErrorBase< T, ErrorWeightType >::matrix(), mathSSE::sqrt(), PV3DBase< T, PVType, FrameType >::x(), PV3DBase< T, PVType, FrameType >::y(), and PV3DBase< T, PVType, FrameType >::z().

Referenced by VertexMerging::mergeVertex(), InclusiveVertexFinder::nearTracks(), and TrackIPProducer::produce().

{
    AlgebraicSymMatrix33 error = vtx1PositionError.matrix()
      + vtx2PositionError.matrix();
    GlobalVector diff = vtx1Position - vtx2Position;
    AlgebraicVector3 vDiff;
    vDiff[0] = diff.x();
    vDiff[1] = diff.y();
    vDiff[2] = diff.z();
    
    double dist=diff.mag();
    
    double err2 = ROOT::Math::Similarity(error,vDiff);
    double err = 0.;
    if (dist != 0) err  =  sqrt(err2)/dist;
 
     return Measurement1D(dist,err);
}

Measurement1D VertexDistance3D::signedDistance	(	const reco::Vertex &	primVtx,
		const reco::Vertex &	secVtx,
		const GlobalVector &	momentum
	)		const [virtual]

The signed distance is computed using a vector from the primary to the secondary vertex and a given reference vector. The sign is determined by the scalar product of the vector connecting the vertices and the reference vector: if the scalar product is greater than zero, the sign is +1, else -1

Implements VertexDistance.

Definition at line 8 of file VertexDistance3D.cc.

References diffTreeTool::diff, Measurement1D::error(), reco::Vertex::position(), Measurement1D::value(), PV3DBase< T, PVType, FrameType >::x(), Basic3DVector< T >::x(), PV3DBase< T, PVType, FrameType >::y(), Basic3DVector< T >::y(), PV3DBase< T, PVType, FrameType >::z(), and Basic3DVector< T >::z().

{
  Measurement1D unsignedDistance = distance(vtx1, vtx2);
  Basic3DVector<float> diff = Basic3DVector<float> (vtx2.position()) - 
    Basic3DVector<float> (vtx1.position());
//   Basic3DVector<float> (vtx2 - vtx1);
  if ((momentum.x()*diff.x() + momentum.y()*diff.y() * momentum.z()*diff.z()) < 0 )
    return Measurement1D(-1.0*unsignedDistance.value(),unsignedDistance.error());
  return unsignedDistance;
}

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Member Data Documentation

AlgebraicSymMatrix33 VertexDistance3D::theNullMatrix [private]

Definition at line 41 of file VertexDistance3D.h.