---

VertexDistance3D Class Reference

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

#include <RecoVertex/VertexTools/interface/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
	The signed distance is computed using a vector from the primary to the secondary vertex and a given reference vector.
	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
AlgebraicSymMatrix	theNullMatrix

---

Detailed Description

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

Definition at line 14 of file VertexDistance3D.h.

---

Constructor & Destructor Documentation

VertexDistance3D::VertexDistance3D

(

)

[inline]

Definition at line 19 of file VertexDistance3D.h.

Referenced by clone().

: theNullMatrix(3, 0) {}

---

Member Function Documentation

virtual VertexDistance3D* VertexDistance3D::clone

(

void

)

const [inline, virtual]

Implements VertexDistance.

Definition at line 33 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 diff, err1, err2, error, Exception, GlobalErrorBase< T, ErrorWeightType >::matrix(), theNullMatrix, PV3DBase< T, PVType, FrameType >::x(), PV3DBase< T, PVType, FrameType >::y(), and PV3DBase< T, PVType, FrameType >::z().

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

  // position residuals
  GlobalVector diff = vtx2Position - vtx1Position;
  AlgebraicVector vDiff(3);
  vDiff[0] = diff.x();
  vDiff[1] = diff.y();
  vDiff[2] = diff.z();

  // Invert error matrix of residuals
  int ifail;
  error.invert(ifail);
  if (ifail != 0) {
    throw cms::Exception("VertexDistance3D::matrix inversion problem");
  }

  return error.similarity(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 diff, dist(), err, err2, error, PV3DBase< T, PVType, FrameType >::mag(), GlobalErrorBase< T, ErrorWeightType >::matrix(), funct::sqrt(), PV3DBase< T, PVType, FrameType >::x(), PV3DBase< T, PVType, FrameType >::y(), and PV3DBase< T, PVType, FrameType >::z().

Referenced by signedDistance().

{
    AlgebraicSymMatrix error = vtx1PositionError.matrix()
      + vtx2PositionError.matrix();
    GlobalVector diff = vtx1Position - vtx2Position;
    AlgebraicVector vDiff(3);
    vDiff[0] = diff.x();
    vDiff[1] = diff.y();
    vDiff[2] = diff.z();
    
    double dist=diff.mag();
    
    double err2 = error.similarity(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 diff, distance(), 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;
}

---

Member Data Documentation

AlgebraicSymMatrix VertexDistance3D::theNullMatrix [private]

Definition at line 42 of file VertexDistance3D.h.

Referenced by compatibility().

---

The documentation for this class was generated from the following files:

• RecoVertex/VertexTools/interface/VertexDistance3D.h
• RecoVertex/VertexTools/src/VertexDistance3D.cc

---