ExtendedRiemannsMethod Class Reference

Class implementing the Riemann fit for two dimensional trajectory circle. More...

#include <ExtendedRiemannsMethod.h>

Inheritance diagram for ExtendedRiemannsMethod:

Public Member Functions
	ExtendedRiemannsMethod ()
	Constructor setting the default constraints.
void	update (TrackingUtilities::CDCTrajectory2D &trajectory2D, CDCObservations2D &observations2D) const
	Executes the fit and updates the trajectory parameters This may render the information in the observation object.
bool	isLineConstrained () const
	Getter for the indicator that lines should be fitted by this fitter.
bool	isOriginConstrained () const
	Getter for the indicator that curves through the origin should be fitted by this fitter.
void	setLineConstrained (bool constrained=true)
	Indicator if this fitter is setup to fit lines.
void	setOriginConstrained (bool constrained=true)
	Indicator if this fitter is setup to fit curves through the origin.

Private Member Functions
TrackingUtilities::UncertainPerigeeCircle	fitInternal (CDCObservations2D &observations2D) const
	Internal method doing the heavy work.

Private Attributes
bool	m_lineConstrained
	Memory for the flag indicating that lines should be fitted.
bool	m_originConstrained
	Memory for the flag indicating that curves through the origin shall be fitter.

Detailed Description

Class implementing the Riemann fit for two dimensional trajectory circle.

Definition at line 24 of file ExtendedRiemannsMethod.h.

Constructor & Destructor Documentation

ExtendedRiemannsMethod()

ExtendedRiemannsMethod

(

)

Constructor setting the default constraints.

Definition at line 31 of file ExtendedRiemannsMethod.cc.

  : m_lineConstrained(false)
  , m_originConstrained(false)
{
}

Member Function Documentation

fitInternal()

UncertainPerigeeCircle fitInternal ( CDCObservations2D & observations2D ) const

private

Internal method doing the heavy work.

Definition at line 297 of file ExtendedRiemannsMethod.cc.

{
  using namespace NParabolicParameterIndices;
 
  // Matrix of weighted sums
  Eigen::Matrix< double, 5, 5 > s = getWXYRLSumMatrix(observations2D);
 
  // The same as above without drift lengths
  Eigen::Matrix<double, 4, 4> sNoL = s.block<4, 4>(0, 0);
 
  // Determine NDF : Circle fit eats up to 3 degrees of freedom depending on the constraints
  size_t ndf = observations2D.size() - 1;
 
  if (not isOriginConstrained()) {
    --ndf;
  }
 
  if (not isLineConstrained()) {
    --ndf;
  }
 
  // Parameters to be fitted
  UncertainPerigeeCircle resultCircle;
  double chi2 = 0;
 
  size_t nObservationsWithDriftRadius = observations2D.getNObservationsWithDriftRadius();
  if (nObservationsWithDriftRadius > 0) {
    resultCircle = UncertainPerigeeCircle(::fit(s, isLineConstrained(), isOriginConstrained()));
    chi2 = calcChi2(resultCircle, s);
  } else {
    if (not isOriginConstrained()) {
      // Alternative implementation for comparison
 
      // Matrix of averages
      Eigen::Matrix< double, 4, 4> aNoL = sNoL / sNoL(iW);
 
      // Measurement means
      Eigen::Matrix< double, 4, 1> meansNoL = aNoL.row(iW);
 
      // Covariance matrix
      Eigen::Matrix< double, 4, 4> cNoL = aNoL - meansNoL * meansNoL.transpose();
 
      resultCircle = UncertainPerigeeCircle(fitSeperateOffset(meansNoL, cNoL, isLineConstrained()));
 
    } else {
      resultCircle = UncertainPerigeeCircle(::fit(sNoL, isLineConstrained(), isOriginConstrained()));
    }
 
    chi2 = calcChi2(resultCircle, sNoL);
  }
 
  // Covariance calculation does not need the drift lengths, which is why we do not forward them.
  PerigeePrecision perigeePrecision =
    calcPrecision(resultCircle, sNoL, isLineConstrained(), isOriginConstrained());
 
  // Use in pivoting in case the matrix is not full rank as it is for the constrained cases
  PerigeeCovariance perigeeCovariance = PerigeeUtil::covarianceFromPrecision(perigeePrecision);
 
  resultCircle.setNDF(ndf);
  resultCircle.setChi2(chi2);
  resultCircle.setPerigeeCovariance(perigeeCovariance);
  return resultCircle;
}

isLineConstrained()

bool isLineConstrained ( ) const

inline

Getter for the indicator that lines should be fitted by this fitter.

Definition at line 42 of file ExtendedRiemannsMethod.h.

      {
        return m_lineConstrained;
      }

isOriginConstrained()

bool isOriginConstrained ( ) const

inline

Getter for the indicator that curves through the origin should be fitted by this fitter.

Definition at line 48 of file ExtendedRiemannsMethod.h.

      {
        return m_originConstrained;
      }

setLineConstrained()

void setLineConstrained ( bool constrained = true )

inline

Indicator if this fitter is setup to fit lines.

Definition at line 54 of file ExtendedRiemannsMethod.h.

      {
        m_lineConstrained = constrained;
      }

setOriginConstrained()

void setOriginConstrained ( bool constrained = true )

inline

Indicator if this fitter is setup to fit curves through the origin.

Definition at line 60 of file ExtendedRiemannsMethod.h.

      {
        m_originConstrained = constrained;
      }

update()

void update	(	TrackingUtilities::CDCTrajectory2D &	trajectory2D,
		CDCObservations2D &	observations2D ) const

Executes the fit and updates the trajectory parameters This may render the information in the observation object.

Definition at line 37 of file ExtendedRiemannsMethod.cc.

{
  size_t nObservations = observations2D.size();
  trajectory2D.clear();
  if (not nObservations) return;
 
  ROOT::Math::XYVector origin = ROOT::Math::XYVector(0.0, 0.0);
  ROOT::Math::XYVector centralPoint = observations2D.getCentralPoint();
 
  const ROOT::Math::XYVector& ref = isOriginConstrained() ? origin : centralPoint;
  observations2D.passiveMoveBy(ref);
 
  UncertainPerigeeCircle perigeeCircle = fitInternal(observations2D);
 
  double frontX = observations2D.getX(0);
  double frontY = observations2D.getY(0);
  ROOT::Math::XYVector frontPos(frontX, frontY);
 
  double backX = observations2D.getX(nObservations - 1);
  double backY = observations2D.getY(nObservations - 1);
  ROOT::Math::XYVector backPos(backX, backY);
 
  ROOT::Math::XYVector overPos(0, 0);
  double totalPerps = (perigeeCircle->arcLengthBetween(frontPos, overPos) +
                       perigeeCircle->arcLengthBetween(overPos, backPos));
 
  if (totalPerps < 0) {
    perigeeCircle.reverse();
  }
 
  trajectory2D = CDCTrajectory2D(ref, perigeeCircle);
}

Member Data Documentation

m_lineConstrained

bool m_lineConstrained

private

Memory for the flag indicating that lines should be fitted.

Definition at line 67 of file ExtendedRiemannsMethod.h.

m_originConstrained

bool m_originConstrained

private

Memory for the flag indicating that curves through the origin shall be fitter.

Definition at line 70 of file ExtendedRiemannsMethod.h.

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

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