QualityEstimatorLineFit3D Class Reference

Testbeam: Coords: Sensors: ^ . More...

#include <QualityEstimatorLineFit3D.h>

Inheritance diagram for QualityEstimatorLineFit3D:

Collaboration diagram for QualityEstimatorLineFit3D:

Public Member Functions
virtual double	estimateQuality (std::vector< SpacePoint const * > const &measurements) final
	Minimal implementation of the quality estimation Calculates quality indicator in range [0,1]. More...
void	setMagneticFieldStrength (double magneticFieldZ=1.5)
	Setter for z component of magnetic field. More...
virtual QualityEstimationResults	estimateQualityAndProperties (std::vector< SpacePoint const * > const &measurements)
	Quality estimation providing additional quantities Calculates quality indicator in range [0,1] Optionally returns chi2 and additional informations. More...

Protected Member Functions
double	calcPt (double const radius) const
	Returns a value for the transverse momentum in GeV calculated from a provided radius. More...

Protected Attributes
double	m_magneticFieldZ = 1.5
	Member storing the z component of the magnetic field.
QualityEstimationResults	m_results
	Result of the quality estimation This is stored as a member variable, because some values may be calculated by 'estimateQuality' anyways. More...

Detailed Description

Testbeam: Coords: Sensors: ^ .

/| ./| ./| | ^ | | | | | | |Y /Z | | | | | | |/ |/ |/ |/ ----—> X

beam parallel to x. Measurement errors in y & z (v&u) With these conditions, the following approach using 2 independent 2D line fits is acceptable (if rotation is the same for all sensors): Modells: Y_i = a*X_i + b Z_i = c*X_i + d

Definition at line 32 of file QualityEstimatorLineFit3D.h.

Member Function Documentation

calcPt()

double calcPt ( double const  radius ) const

inlineprotectedinherited

Returns a value for the transverse momentum in GeV calculated from a provided radius.

Utilizing m_magneticFieldZ and hard coded speed of light

Definition at line 82 of file QualityEstimatorBase.h.

estimateQuality()

double estimateQuality ( std::vector< SpacePoint const * > const &  measurements )

finalvirtual

Minimal implementation of the quality estimation Calculates quality indicator in range [0,1].

measurements - std::vector<SpacePoint const*> ordered from innermost to outermost measurement

Implements QualityEstimatorBase.

Definition at line 15 of file QualityEstimatorLineFit3D.cc.

{
  TVector3 directionVector;
  double sumWyi = 0, // sum of weights for Yi
         sumWzi = 0, // sum of weights for Zi
         sumWyiXi = 0, // sum of (y-weights times x-values)
         sumWziXi = 0, // sum of (z-weights times x-values)
         sumWyiYi = 0, // sum of (y-weights times y-values)
         sumWziZi = 0, // sum of (z-weights times z-values)
         sumWyiXiYi = 0, // sum of (y-weights times x-values times y-values)
         sumWziXiZi = 0, // sum of (z-weights times x-values times z-values)
         sumWyiXi2 = 0, // sum of (y-weights times x-values^2)
         sumWziXi2 = 0, // sum of (z-weights times x-values^2)
         detValY = 0, // determinant for norming values - y
         detValZ = 0, // determinant for norming values - z
         slopeY = 0, // = a of model
         slopeZ = 0, // = c of model
         chi2 = 0, // final chi2-value of fit
         interceptY = 0, // b of model, needed only for chi2-calculation
         interceptZ = 0; // d of model, needed only for chi2-calculation
 
  // NOTE: this approach is not optimal. Maybe can be optimized for less redundancy
  for (const SpacePoint* aHit : measurements) {
    double Wyi = (1. / (aHit->getPositionError().Y() * aHit->getPositionError().Y()));
    double Wzi = (1. / (aHit->getPositionError().Z() * aHit->getPositionError().Z()));
 
    sumWyi += Wyi;
    sumWzi += Wzi;
 
    sumWyiXi += Wyi * aHit->getPosition().X();
    sumWziXi += Wzi * aHit->getPosition().X();
 
    sumWyiYi += Wyi * aHit->getPosition().Y();
    sumWziZi += Wzi * aHit->getPosition().Z();
 
    sumWyiXiYi += Wyi * aHit->getPosition().X() * aHit->getPosition().Y();
    sumWziXiZi += Wzi * aHit->getPosition().X() * aHit->getPosition().Z();
 
    sumWyiXi2 += Wyi * aHit->getPosition().X() * aHit->getPosition().X();
    sumWziXi2 += Wzi * aHit->getPosition().X() * aHit->getPosition().X();
  }
 
  detValY = sumWyiXi2 * sumWyi - sumWyiXi * sumWyiXi;
  if (detValY == 0) {
    return 0;
  }
  detValY = 1. / detValY; // invert
 
  detValZ = sumWziXi2 * sumWzi - sumWziXi * sumWziXi;
  if (detValZ == 0) {
    return 0;
  }
  detValZ = 1. / detValZ; // invert
 
  slopeY = detValY * (sumWyi * sumWyiXiYi  -  sumWyiXi * sumWyiYi);
  slopeZ = detValZ * (sumWzi * sumWziXiZi  -  sumWziXi * sumWziZi);
 
  interceptY = detValY * (- sumWyiXi * sumWyiXiYi  +  sumWyiXi2 * sumWyiYi);
  interceptZ = detValZ * (- sumWziXi * sumWziXiZi  +  sumWziXi2 * sumWziZi);
 
  for (const SpacePoint* aHit : measurements) {  // chi2 of xy-fit and of xz-fit can be combined by adding their values
    chi2 += pow(((aHit->getPosition().Y() - slopeY * aHit->getPosition().X() - interceptY) / aHit->getPositionError().Y()) , 2)
            + pow(((aHit->getPosition().Z() - slopeZ * aHit->getPosition().X() - interceptZ) / aHit->getPositionError().Z()) , 2);
  }
  m_results.chiSquared = chi2;
 
  //m_results.p = B2Vector3<double>(1, slopeY, slopeZ);
 
  return TMath::Prob(chi2,  measurements.size() - 1);
}

estimateQualityAndProperties()

virtual QualityEstimationResults estimateQualityAndProperties ( std::vector< SpacePoint const * > const &  measurements )

inlinevirtualinherited

Quality estimation providing additional quantities Calculates quality indicator in range [0,1] Optionally returns chi2 and additional informations.

Eg. momentum estimation.

measurements - std::vector<SpacePoint const*> ordered from innermost to outermost measurement

Reimplemented in QualityEstimatorMC, and QualityEstimatorTripletFit.

Definition at line 70 of file QualityEstimatorBase.h.

setMagneticFieldStrength()

void setMagneticFieldStrength ( double  magneticFieldZ = 1.5 )

inlineinherited

Setter for z component of magnetic field.

Parameters

magneticFieldZ

: value to set it to

Definition at line 55 of file QualityEstimatorBase.h.

Member Data Documentation

m_results

QualityEstimationResults m_results

protectedinherited

Result of the quality estimation This is stored as a member variable, because some values may be calculated by 'estimateQuality' anyways.

Therefore they don't need to be calculated explicitly in 'estimateQualityAndProperties'.

Definition at line 92 of file QualityEstimatorBase.h.

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

• tracking/trackFindingVXD/trackQualityEstimators/include/QualityEstimatorLineFit3D.h
• tracking/trackFindingVXD/trackQualityEstimators/src/QualityEstimatorLineFit3D.cc