CDCSZObservations Class Reference

Class serving as a storage of observed sz positions to present to the sz line fitters. More...

#include <CDCSZObservations.h>

Public Member Functions
	CDCSZObservations (EFitVariance fitVariance=EFitVariance::c_Proper, bool onlyStereo=false)
	Constructor taking in preferred variance which is taken from the various hit objects if present.
std::size_t	size () const
	Returns the number of observations stored.
double *	data ()
	Return the pointer to the number buffer.
bool	empty () const
	Returns true if there are no observations stored.
void	clear ()
	Removes all observations stored.
void	reserve (std::size_t nObservations)
	Reserves enough space for nObservations.
double	getS (int iObservation) const
	Getter for the arc length value of the observation at the given index.
double	getZ (int iObservation) const
	Getter for the z value of the observation at the given index.
double	getWeight (int iObservation) const
	Getter for the weight / inverse variance of the observation at the given index.
std::size_t	fill (double s, double z, double weight=1.0)
	Appends the observed position.
std::size_t	append (const CDCRecoHit3D &recoHit3D)
	Appends the observed position.
std::size_t	appendRange (const std::vector< CDCRecoHit3D > &recoHit3Ds)
	Appends all reconstructed hits from the three dimensional track.
std::size_t	appendRange (const CDCSegment3D &segment3D)
	Appends all reconstructed hits from the three dimensional segment.
std::size_t	appendRange (const CDCTrack &track)
	Appends all reconstructed hits from the three dimensional track.
Vector2D	getCentralPoint () const
	Extracts the observation center that is at the index in the middle.
void	passiveMoveBy (const Vector2D &origin)
	Moves all observations passively such that the given vector becomes to origin of the new coordinate system.
Vector2D	centralize ()
	Picks one observation as a reference point and transform all observations to that new origin.
void	setFitVariance (EFitVariance fitVariance)
	Setter for the indicator that the drift variance should be used.

Private Attributes
std::vector< double >	m_szObservations
	Memory for the individual observations.
EFitVariance	m_fitVariance
	Indicator which variance information should preferably be extracted from hits in calls to append.
bool	m_onlyStereo
	Switch to only use information from stereo hits.

Detailed Description

Class serving as a storage of observed sz positions to present to the sz line fitters.

Definition at line 26 of file CDCSZObservations.h.

Constructor & Destructor Documentation

CDCSZObservations()

CDCSZObservations ( EFitVariance  fitVariance = EFitVariance::c_Proper, bool  onlyStereo = false  )

inlineexplicit

Constructor taking in preferred variance which is taken from the various hit objects if present.

Parameters

fitVariance	Variance information to be used Currently only c_Unit and c_Proper are supported.
onlyStereo	Switch to only use the information of stereo hits.

Definition at line 36 of file CDCSZObservations.h.

        : m_fitVariance(fitVariance)
        , m_onlyStereo(onlyStereo)
      {
      }

Member Function Documentation

append()

std::size_t append

(

const CDCRecoHit3D &

recoHit3D

)

Appends the observed position.

Definition at line 38 of file CDCSZObservations.cc.

{
  if (m_onlyStereo and recoHit3D.isAxial()) return 0;
 
  const double s = recoHit3D.getArcLength2D();
  const double z = recoHit3D.getRecoPos3D().z();
 
  double weight = 1.0;
  if (m_fitVariance == EFitVariance::c_Unit) {
    weight = 1;
  } else {
    // Translate the drift length uncertainty to a uncertainty in z
    // by the taking the projected wire vector part parallel to the displacement
    // as a proportionality factor to the z direction.
    const CDCWire& wire = recoHit3D.getWire();
    const Vector3D& wireVector = wire.getWireVector();
    const Vector2D disp2D = recoHit3D.getRecoDisp2D();
    const double driftlengthVariance = recoHit3D.getRecoDriftLengthVariance();
 
    double dispNorm = disp2D.norm();
 
    double zeta = 1.0;
    if (dispNorm == 0.0) {
      zeta = wireVector.xy().norm() / wireVector.z();
    } else {
      zeta = wireVector.xy().dot(disp2D) / wireVector.z() / dispNorm;
    }
 
    weight = zeta * zeta / driftlengthVariance;
  }
 
  size_t appendedHit = fill(s, z, weight);
  return appendedHit;
}

appendRange() [1/3]

std::size_t appendRange

(

const CDCSegment3D &

segment3D

)

Appends all reconstructed hits from the three dimensional segment.

Returns

Number of added hits

Definition at line 82 of file CDCSZObservations.cc.

{
  const std::vector<CDCRecoHit3D> recoHit3Ds = segment3D;
  return this->appendRange(recoHit3Ds);
}

appendRange() [2/3]

std::size_t appendRange

(

const CDCTrack &

track

)

Appends all reconstructed hits from the three dimensional track.

Returns

Number of added hits

Definition at line 88 of file CDCSZObservations.cc.

{
  const std::vector<CDCRecoHit3D> recoHit3Ds = track;
  return this->appendRange(recoHit3Ds);
}

appendRange() [3/3]

std::size_t appendRange

(

const std::vector< CDCRecoHit3D > &

recoHit3Ds

)

Appends all reconstructed hits from the three dimensional track.

Returns

Number of added hits

Definition at line 73 of file CDCSZObservations.cc.

{
  std::size_t nAppendedHits = 0;
  for (const CDCRecoHit3D& recoHit3D : recoHit3Ds) {
    nAppendedHits += append(recoHit3D);
  }
  return nAppendedHits;
}

centralize()

Vector2D centralize

(

)

Picks one observation as a reference point and transform all observations to that new origin.

Definition at line 118 of file CDCSZObservations.cc.

{
  // Pick an observation at the center
  Vector2D centralPoint = getCentralPoint();
  passiveMoveBy(centralPoint);
  return centralPoint;
}

clear()

void clear ( )

inline

Removes all observations stored.

Definition at line 63 of file CDCSZObservations.h.

      {
        m_szObservations.clear();
      }

data()

double * data ( )

inline

Return the pointer to the number buffer.

Definition at line 51 of file CDCSZObservations.h.

      {
        return m_szObservations.data();
      }

empty()

bool empty ( ) const

inline

Returns true if there are no observations stored.

Definition at line 57 of file CDCSZObservations.h.

      {
        return m_szObservations.empty();
      }

fill()

std::size_t fill	(	double	s,
		double	z,
		double	weight = 1.0
	)

Appends the observed position.

Note

Observations are skipped, if one of the given variables is NAN.

Parameters

s	S coordinate of the center of the observed position.
z	Z coordinate of the center of the observed position.
weight	The relative weight of the observation. In order to generate a unit less chi^2 measure the weight should be chosen as the inverse variance of the drift length. Defaults to 1.

Returns

Number of observations added. One if the observation was added. Zero if one of the given variables is NAN.

Definition at line 23 of file CDCSZObservations.cc.

{
  if (std::isnan(s)) return 0;
  if (std::isnan(z)) return 0;
  if (std::isnan(weight)) {
    B2WARNING("Weight is nan. Skipping observation");
    return 0;
  }
 
  m_szObservations.push_back(s);
  m_szObservations.push_back(z);
  m_szObservations.push_back(weight);
  return 1;
}

getCentralPoint()

Vector2D getCentralPoint

(

)

const

Extracts the observation center that is at the index in the middle.

Definition at line 94 of file CDCSZObservations.cc.

{
  std::size_t n = size();
  if (n == 0) return Vector2D(NAN, NAN);
  std::size_t i = n / 2;
 
  if (isEven(n)) {
    // For even number of observations use the middle one with the bigger distance from IP
    Vector2D center1(getS(i), getZ(i));
    Vector2D center2(getS(i - 1), getZ(i - 1));
    return center1.normSquared() > center2.normSquared() ? center1 : center2;
  } else {
    Vector2D center1(getS(i), getZ(i));
    return center1;
  }
}

getS()

double getS ( int  iObservation ) const

inline

Getter for the arc length value of the observation at the given index.

Definition at line 75 of file CDCSZObservations.h.

      {
        return m_szObservations[iObservation * 3];
      }

getWeight()

double getWeight ( int  iObservation ) const

inline

Getter for the weight / inverse variance of the observation at the given index.

Definition at line 87 of file CDCSZObservations.h.

      {
        return m_szObservations[iObservation * 3 + 2];
      }

getZ()

double getZ ( int  iObservation ) const

inline

Getter for the z value of the observation at the given index.

Definition at line 81 of file CDCSZObservations.h.

      {
        return m_szObservations[iObservation * 3 + 1];
      }

passiveMoveBy()

void passiveMoveBy

(

const Vector2D &

origin

)

Moves all observations passively such that the given vector becomes to origin of the new coordinate system.

Definition at line 111 of file CDCSZObservations.cc.

{
  Eigen::Matrix<double, 1, 2> eigenOrigin(origin.x(), origin.y());
  EigenObservationMatrix eigenObservations = getEigenObservationMatrix(this);
  eigenObservations.leftCols<2>().rowwise() -= eigenOrigin;
}

reserve()

void reserve ( std::size_t  nObservations )

inline

Reserves enough space for nObservations.

Definition at line 69 of file CDCSZObservations.h.

      {
        m_szObservations.reserve(nObservations * 3);
      }

setFitVariance()

void setFitVariance ( EFitVariance  fitVariance )

inline

Setter for the indicator that the drift variance should be used.

Definition at line 137 of file CDCSZObservations.h.

      {
        m_fitVariance = fitVariance;
      }

size()

std::size_t size ( ) const

inline

Returns the number of observations stored.

Definition at line 45 of file CDCSZObservations.h.

      {
        return m_szObservations.size() / 3;
      }

Member Data Documentation

m_fitVariance

EFitVariance m_fitVariance

private

Indicator which variance information should preferably be extracted from hits in calls to append.

Meaning of the constants detailed in EFitVariance.

Definition at line 154 of file CDCSZObservations.h.

m_onlyStereo

bool m_onlyStereo

private

Switch to only use information from stereo hits.

Definition at line 157 of file CDCSZObservations.h.

m_szObservations

std::vector<double> m_szObservations

private

Memory for the individual observations.

Arrangement of values is s, z, weight, s, z, .....

Definition at line 147 of file CDCSZObservations.h.

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

• tracking/trackFindingCDC/fitting/include/CDCSZObservations.h
• tracking/trackFindingCDC/fitting/src/CDCSZObservations.cc