Class that allows the calculation of simple variables to estimate the quality of a triplet of hits. More...

#include <ThreeHitVariables.h>

Public Member Functions
	ThreeHitVariables ()
	basic constructor

	ThreeHitVariables (const B2Vector3D &oHit, const B2Vector3D &cHit, const B2Vector3D &iHit)
	actual useful constructor

void	setHits (const B2Vector3D &oHit, const B2Vector3D &cHit, const B2Vector3D &iHit)
	Set hits if not given in constructor of if they need to be changed.

double	calcAvgDistanceXY (const B2Vector3D &circleCenter)
	helper function which calculates the average distance in XY from the given center

double	getAngle3D ()
	calculates the angle between the hits/vectors (3D), returning unit: angle in radian

double	getAngle3DSimple ()
	calculates the angle between the hits/vectors (3D), returning unit: none (calculation for degrees is incomplete, if you want readable numbers, use Angle3DFull instead)

double	getAngleRZ ()
	calculates the angle between the hits/vectors (RZ), returning unit: angle in radian

double	getCosAngleRZSimple ()
	calculates the cosine of the angle between the hits/vectors (RZ), returning unit: none (calculation for degrees is incomplete, if you want readable numbers, use AngleRZFull instead)

double	getAngleXY ()
	Calculates the angle in x-y between two vectors return unit: rad (0 - pi)

B2Vector3D	getCircleCenterXY ()
	calculates an estimation of circleCenter position, result is returned as the x and y value of the B2Vector3.

double	getCircleDistanceIP ()
	calculates the distance of the point of closest approach of circle to the IP, returning unit: cm

double	getCircleRadius ()
	calculates the estimation of the circle radius of the 3-hit-tracklet, returning unit: cm.

double	getCosAngleXY ()
	calculates the angle between the hits/vectors (XY), returning unit: none (calculation for degrees is incomplete, if you want readable numbers, use AngleXYFull instead)

double	getDeltaSlopeRZ ()
	calculates deviations in the slope of the inner segment and the outer segment, returning unit: none

double	getDeltaSlopeZoverS ()
	compares the "slopes" z over arc length. calcDeltaSlopeZOverS is invariant under rotations in the r-z plane.

double	getDeltaSoverZ ()
	calculates the helixparameter describing the deviation in arc length per unit in z. returning unit: radians*cm

double	performHelixParamterFit ()
	calculates the helixparameter describing the deviation in z per unit angle, returning unit: none

double	getSimplePTEstimate ()
	calculates the estimation of the transverse momentum of the 3-hit-tracklet, returning unit: GeV/c

int	getCurvatureSign ()
	calculates calculates the sign of the curvature of given 3-hit-tracklet.

void	setBFieldZ (const double bfieldZ=1.5)
	Set the B-Field value used for pT calculations.

Static Public Member Functions
static int	getCurvatureSign (const B2Vector3D &oHit, const B2Vector3D &cHit, const B2Vector3D &iHit)
	calculates calculates the sign of the curvature of 3-hit-tracklet given as arguments.

Private Attributes
B2Vector3D	m_oHit
	outermost hit position

B2Vector3D	m_cHit
	center hit position

B2Vector3D	m_iHit
	innermost hit position

B2Vector3D	m_outerDifferenceVector
	The following two differences are used very often, so calculate once on construction vector containing the difference m_oHit - m_cHit.

B2Vector3D	m_innerDifferenceVector
	vector containing the difference m_cHit - m_iHit

double	m_BFieldZ = 1.5
	BField along z to estimate pT.

Detailed Description

Class that allows the calculation of simple variables to estimate the quality of a triplet of hits.

Definition at line 24 of file ThreeHitVariables.h.

Constructor & Destructor Documentation

◆ ThreeHitVariables() [1/2]

ThreeHitVariables ( )

inline

basic constructor

Definition at line 27 of file ThreeHitVariables.h.

                          : m_oHit(0., 0., 0.), m_cHit(0., 0., 0.), m_iHit(0., 0., 0.),
        m_outerDifferenceVector(0., 0., 0.), m_innerDifferenceVector(0., 0., 0.)
      {};

◆ ThreeHitVariables() [2/2]

ThreeHitVariables	(	const B2Vector3D &	oHit,
		const B2Vector3D &	cHit,
		const B2Vector3D &	iHit )

inline

actual useful constructor

Parameters

oHit	B2Vector3D of the outer hit used for calculating the single variables
cHit	B2Vector3D of the center hit used for calculating the single variables
iHit	B2Vector3D of the inner hit used for calculating the single variables

Definition at line 35 of file ThreeHitVariables.h.

                                                                                                :
        m_oHit(oHit), m_cHit(cHit), m_iHit(iHit),
        m_outerDifferenceVector(oHit - cHit), m_innerDifferenceVector(cHit - iHit)
      {
      };

Member Function Documentation

◆ calcAvgDistanceXY()

double calcAvgDistanceXY ( const B2Vector3D & circleCenter )

inline

helper function which calculates the average distance in XY from the given center

Parameters

circleCenter center of the circle for which the average distance is calculated returns the average distance in cm of the hits to the circle center position

Definition at line 57 of file ThreeHitVariables.h.

      {
        return (sqrt(std::pow(circleCenter.X() - m_oHit.X(), 2) + std::pow(circleCenter.Y() - m_oHit.Y(), 2)) +
                sqrt(std::pow(circleCenter.X() - m_cHit.X(), 2) + std::pow(circleCenter.Y() - m_cHit.Y(), 2)) +
                sqrt(std::pow(circleCenter.X() - m_iHit.X(), 2) + std::pow(circleCenter.Y() - m_iHit.Y(), 2))) / 3.;
      }

◆ getAngle3D()

double getAngle3D ( )

inline

calculates the angle between the hits/vectors (3D), returning unit: angle in radian

Definition at line 66 of file ThreeHitVariables.h.

      {
        double result = acos(m_outerDifferenceVector.Dot(m_innerDifferenceVector) /
                             (m_outerDifferenceVector.Mag() * m_innerDifferenceVector.Mag())); // 0-pi
        return (std::isnan(result) || std::isinf(result)) ? double(0) : result;
      }

◆ getAngle3DSimple()

double getAngle3DSimple ( )

inline

calculates the angle between the hits/vectors (3D), returning unit: none (calculation for degrees is incomplete, if you want readable numbers, use Angle3DFull instead)

Definition at line 75 of file ThreeHitVariables.h.

      {
        // fullCalc would be acos(m_vecAB.Dot(m_vecBC) / m_vecAB.Mag()*m_vecBC.Mag()), but here time-consuming parts have been neglected
        double result = m_outerDifferenceVector.Dot(m_innerDifferenceVector) /
                        (m_outerDifferenceVector.Mag2() * m_innerDifferenceVector.Mag2());
        return (std::isnan(result) || std::isinf(result)) ? double(0) : result;
      }

◆ getAngleRZ()

double getAngleRZ ( )

inline

calculates the angle between the hits/vectors (RZ), returning unit: angle in radian

Definition at line 85 of file ThreeHitVariables.h.

      {
        B2Vector3D rzVecAB(m_outerDifferenceVector.Perp(), m_outerDifferenceVector.Z(), 0.);
        B2Vector3D rzVecBC(m_innerDifferenceVector.Perp(), m_innerDifferenceVector.Z(), 0.);
        TwoHitVariables twoHitVariables(rzVecAB, rzVecBC);
 
        double result = acos(twoHitVariables.getCosXY());  // 0-pi
        return (std::isnan(result) || std::isinf(result)) ? double(0) : result;
      } // return unit: rad (0 - pi)

◆ getAngleXY()

double getAngleXY ( )

inline

Calculates the angle in x-y between two vectors return unit: rad (0 - pi)

Definition at line 108 of file ThreeHitVariables.h.

      {
        TwoHitVariables twoHitVariables(m_outerDifferenceVector, m_innerDifferenceVector);
        double result = acos(twoHitVariables.getCosXY());   // 0-pi
        return (std::isnan(result) || std::isinf(result)) ? double(0) : result;
      }

◆ getCircleCenterXY()

B2Vector3D getCircleCenterXY ( )

inline

calculates an estimation of circleCenter position, result is returned as the x and y value of the B2Vector3.

Definition at line 117 of file ThreeHitVariables.h.

      {
        // calculates the intersection point using Cramer's rule.
        // x_1+s*n_1==x_2+t*n_2 --> n_1 *s - n_2 *t == x_2 - x_1 --> http://en.wikipedia.org/wiki/Cramer%27s_rule
        double inX = m_cHit.X() - m_iHit.X(); // x value of the normal vector of the inner segment (m_cHit-m_iHit)
        double inY = m_cHit.Y() - m_iHit.Y(); // y value of the normal vector of the inner segment (m_cHit-m_iHit)
        double outX = m_oHit.X() - m_cHit.X(); // x value of the normal vector of the outer segment (m_oHit-m_cHit)
        double outY = m_oHit.Y() - m_cHit.Y(); // y value of the normal vector of the outer segment (m_oHit-m_cHit)
 
        // searching solution for Ax = b, aij are the matrix elements of A, bi are elements of b
        double a11 = inY;
        double a12 = -inX;
        double a21 = -outY;
        double a22 = outX;
        double b1 = m_cHit.X() + outX * 0.5 - (m_iHit.X() + inX * 0.5);
        double b2 = m_cHit.Y() + outY * 0.5 - (m_iHit.Y() + inY * 0.5);
 
        // protect against the determinant being zero
        if (a11 * a22 == a12 * a21) {
          return B2Vector3D(1e30, 1e30, 1e30);
        }
 
        // the determinant is zero if the three hits are on a line in (x,y), which is checked above.
        double s = (b1 * a22 - b2 * a21) / (a11 * a22 - a12 * a21);
 
        return B2Vector3D(m_iHit.X() + inX * 0.5 + s * inY, m_iHit.Y() + inY * 0.5 - s * inX, 0.);
      }

◆ getCircleDistanceIP()

double getCircleDistanceIP ( )

inline

calculates the distance of the point of closest approach of circle to the IP, returning unit: cm

Definition at line 147 of file ThreeHitVariables.h.

      {
        B2Vector3D circleCenter = getCircleCenterXY();
        if (circleCenter.Perp2() > 1e30) {
          return NAN;
        }
        double circleRadius = calcAvgDistanceXY(circleCenter);
 
        // distance of closest approach of circle to the IP :
        // WARNING only valid for IP=0,0,X
        return (fabs(circleCenter.Perp() - circleRadius));
      }

◆ getCircleRadius()

double getCircleRadius ( )

inline

calculates the estimation of the circle radius of the 3-hit-tracklet, returning unit: cm.

Definition at line 162 of file ThreeHitVariables.h.

      {
        B2Vector3D circleCenter = getCircleCenterXY();
        if (circleCenter.Perp2() > 1e30) {
          return NAN;
        }
        return calcAvgDistanceXY(circleCenter);
      }

◆ getCosAngleRZSimple()

double getCosAngleRZSimple ( )

inline

calculates the cosine of the angle between the hits/vectors (RZ), returning unit: none (calculation for degrees is incomplete, if you want readable numbers, use AngleRZFull instead)

Definition at line 97 of file ThreeHitVariables.h.

      {
        B2Vector3D rzVecAB(m_outerDifferenceVector.Perp(), m_outerDifferenceVector.Z(), 0.);
        B2Vector3D rzVecBC(m_innerDifferenceVector.Perp(), m_innerDifferenceVector.Z(), 0.);
        TwoHitVariables twoHitVariables(rzVecAB, rzVecBC);
 
        return twoHitVariables.getCosXY();
      }

◆ getCosAngleXY()

double getCosAngleXY ( )

inline

calculates the angle between the hits/vectors (XY), returning unit: none (calculation for degrees is incomplete, if you want readable numbers, use AngleXYFull instead)

Definition at line 174 of file ThreeHitVariables.h.

      {
        double result = (m_outerDifferenceVector.X() * m_innerDifferenceVector.X() +
                         m_outerDifferenceVector.Y() * m_innerDifferenceVector.Y()) /
                        (m_outerDifferenceVector.Perp() * m_innerDifferenceVector.Perp());
 
        return (std::isnan(result) || std::isinf(result)) ? double(0) : result;
      }

◆ getCurvatureSign() [1/2]

int getCurvatureSign ( )

inline

calculates calculates the sign of the curvature of given 3-hit-tracklet.

A positive value represents a left-oriented curvature, a negative value means having a right-oriented curvature. 0 means that it is exactly straight or that two hits are identical.

Definition at line 284 of file ThreeHitVariables.h.

      {
        using boost::math::sign;
        B2Vector3D ba(m_oHit.X() - m_cHit.X(), m_oHit.Y() - m_cHit.Y(), 0.0);
        B2Vector3D bc(m_cHit.X() - m_iHit.X(), m_cHit.Y() - m_iHit.Y(), 0.0);
        return sign(bc.Orthogonal() * ba); //normal vector of m_vecBC times segment of ba
      }

◆ getCurvatureSign() [2/2]

static int getCurvatureSign	(	const B2Vector3D &	oHit,
		const B2Vector3D &	cHit,
		const B2Vector3D &	iHit )

inlinestatic

calculates calculates the sign of the curvature of 3-hit-tracklet given as arguments.

A positive value represents a left-oriented curvature, a negative value means having a right-oriented curvature. 0 means that it is exactly straight or that two hits are identical.

Definition at line 295 of file ThreeHitVariables.h.

      {
        using boost::math::sign;
        B2Vector3D ba(oHit.X() - cHit.X(), oHit.Y() - cHit.Y(), 0.0);
        B2Vector3D bc(cHit.X() - iHit.X(), cHit.Y() - iHit.Y(), 0.0);
        return sign(bc.Orthogonal() * ba); //normal vector of m_vecBC times segment of ba
      }

◆ getDeltaSlopeRZ()

double getDeltaSlopeRZ ( )

inline

calculates deviations in the slope of the inner segment and the outer segment, returning unit: none

Definition at line 185 of file ThreeHitVariables.h.

      {
        TwoHitVariables outerTwoHitVariables(m_oHit, m_cHit);
        TwoHitVariables innerTwoHitVariables(m_cHit, m_iHit);
        double slopeOC = outerTwoHitVariables.getRZSlope();
        double slopeCI = innerTwoHitVariables.getRZSlope();
 
        return slopeCI - slopeOC;
      }

◆ getDeltaSlopeZoverS()

double getDeltaSlopeZoverS ( )

inline

compares the "slopes" z over arc length. calcDeltaSlopeZOverS is invariant under rotations in the r-z plane.

Definition at line 197 of file ThreeHitVariables.h.

      {
        B2Vector3D circleCenter = getCircleCenterXY();
        if (circleCenter.Perp2() > 1e30) {
          return NAN;
        }
        double circleRadius = calcAvgDistanceXY(circleCenter);
        B2Vector3D vecOuter2cC  = m_oHit - circleCenter;
        B2Vector3D vecCenter2cC = m_cHit - circleCenter;
        B2Vector3D vecInner2cC  = m_iHit - circleCenter;
 
        TwoHitVariables outerTwoHitVariables(vecOuter2cC, vecCenter2cC);
        TwoHitVariables innerTwoHitVariables(vecCenter2cC, vecInner2cC);
 
        // WARNING: this is only approximately S (valid in the limit of small angles) but might be OK for this use!!!
        //  want to replace id with 2*sin ( alfa ) * circleRadius
        double alfaOCr = acos(outerTwoHitVariables.getCosXY()) * circleRadius ;
        double alfaCIr = acos(innerTwoHitVariables.getCosXY()) * circleRadius ;
 
        // Beware of z>r!:
        double result = (asin(double(m_oHit.Z() - m_cHit.Z()) / alfaOCr)) - asin(double(m_cHit.Z() - m_iHit.Z()) / alfaCIr);
 
        return (std::isnan(result) || std::isinf(result)) ? double(0) : result;
      }

◆ getDeltaSoverZ()

double getDeltaSoverZ ( )

inline

calculates the helixparameter describing the deviation in arc length per unit in z. returning unit: radians*cm

Definition at line 224 of file ThreeHitVariables.h.

      {
        B2Vector3D circleCenter = getCircleCenterXY();
        if (circleCenter.Perp2() > 1e30) {
          return NAN;
        }
        B2Vector3D vecOuter2cC  = m_oHit - circleCenter;
        B2Vector3D vecCenter2cC = m_cHit - circleCenter;
        B2Vector3D vecInner2cC  = m_iHit - circleCenter;
 
        TwoHitVariables outerTwoHitVariables(vecOuter2cC, vecCenter2cC);
        TwoHitVariables innerTwoHitVariables(vecCenter2cC, vecInner2cC);
        double alfaOC = acos(outerTwoHitVariables.getCosXY());
        double alfaCI = acos(innerTwoHitVariables.getCosXY());
 
        // equals to alfaAB/dZAB and alfaBC/dZBC, but this solution here can not produce a division by zero:
        return (alfaOC * double(m_cHit.Z() - m_iHit.Z())) - (alfaCI * double(m_oHit.Z() - m_cHit.Z()));
      }

◆ getSimplePTEstimate()

double getSimplePTEstimate ( )

inline

calculates the estimation of the transverse momentum of the 3-hit-tracklet, returning unit: GeV/c

Definition at line 269 of file ThreeHitVariables.h.

      {
        B2Vector3D circleCenter = getCircleCenterXY();
        if (circleCenter.Perp2() > 1e30) {
          return NAN;
        }
        double circleRadius = calcAvgDistanceXY(circleCenter);
 
        return 0.00299792458 * m_BFieldZ * circleRadius;
      }

◆ performHelixParamterFit()

double performHelixParamterFit ( )

inline

calculates the helixparameter describing the deviation in z per unit angle, returning unit: none

Definition at line 245 of file ThreeHitVariables.h.

      {
        B2Vector3D circleCenter = getCircleCenterXY();
        if (circleCenter.Perp2() > 1e30) {
          return NAN;
        }
 
        B2Vector3D vecOuter2cC  = m_oHit - circleCenter;
        B2Vector3D vecCenter2cC = m_cHit - circleCenter;
        B2Vector3D vecInner2cC  = m_iHit - circleCenter;
        TwoHitVariables outerTwoHitVariables(vecOuter2cC, vecCenter2cC);
        TwoHitVariables innerTwoHitVariables(vecCenter2cC, vecInner2cC);
 
        double alfaAB = outerTwoHitVariables.getCosXY();
        double alfaBC = innerTwoHitVariables.getCosXY();
 
        // real calculation: ratio is (m_vecij[2] = deltaZ): alfaAB/deltaZab : alfaBC/deltaZbc, the following equation saves two times '/'
        double result = (alfaAB * double(m_cHit.Z() - m_iHit.Z())) / (alfaBC * double(m_oHit.Z() - m_cHit.Z()));
 
        return (std::isnan(result) || std::isinf(result)) ? double(0) : result;
      }

◆ setBFieldZ()

void setBFieldZ ( const double bfieldZ = 1.5 )

inline

Set the B-Field value used for pT calculations.

Parameters

bfieldZ B-Field value to be used

Definition at line 305 of file ThreeHitVariables.h.

305{ m_BFieldZ = bfieldZ; }

◆ setHits()

void setHits	(	const B2Vector3D &	oHit,
		const B2Vector3D &	cHit,
		const B2Vector3D &	iHit )

inline

Set hits if not given in constructor of if they need to be changed.

Parameters

oHit	B2Vector3D of the outer hit used for calculating the single variables
cHit	B2Vector3D of the center hit used for calculating the single variables
iHit	B2Vector3D of the inner hit used for calculating the single variables

Definition at line 45 of file ThreeHitVariables.h.

      {
        m_oHit = oHit;
        m_oHit = oHit;
        m_iHit = iHit;
        m_outerDifferenceVector = oHit - cHit;
        m_innerDifferenceVector = cHit - iHit;
      }

Member Data Documentation

◆ m_BFieldZ

double m_BFieldZ = 1.5

private

BField along z to estimate pT.

Definition at line 320 of file ThreeHitVariables.h.

◆ m_cHit

B2Vector3D m_cHit

private

center hit position

Definition at line 311 of file ThreeHitVariables.h.

◆ m_iHit

B2Vector3D m_iHit

private

innermost hit position

Definition at line 313 of file ThreeHitVariables.h.

◆ m_innerDifferenceVector

B2Vector3D m_innerDifferenceVector

private

vector containing the difference m_cHit - m_iHit

Definition at line 318 of file ThreeHitVariables.h.

◆ m_oHit

B2Vector3D m_oHit

private

outermost hit position

Definition at line 309 of file ThreeHitVariables.h.

◆ m_outerDifferenceVector

B2Vector3D m_outerDifferenceVector

private

The following two differences are used very often, so calculate once on construction vector containing the difference m_oHit - m_cHit.

Definition at line 316 of file ThreeHitVariables.h.

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

tracking/vxdHoughTracking/filters/pathFilters/include/ThreeHitVariables.h

Public Member Functions

Static Public Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ ThreeHitVariables() [1/2]

◆ ThreeHitVariables() [2/2]

Member Function Documentation

◆ calcAvgDistanceXY()

◆ getAngle3D()

◆ getAngle3DSimple()

◆ getAngleRZ()

◆ getAngleXY()

◆ getCircleCenterXY()

◆ getCircleDistanceIP()

◆ getCircleRadius()

◆ getCosAngleRZSimple()

◆ getCosAngleXY()

◆ getCurvatureSign() [1/2]

◆ getCurvatureSign() [2/2]

◆ getDeltaSlopeRZ()

◆ getDeltaSlopeZoverS()

◆ getDeltaSoverZ()

◆ getSimplePTEstimate()

◆ performHelixParamterFit()

◆ setBFieldZ()

◆ setHits()

Member Data Documentation

◆ m_BFieldZ

◆ m_cHit

◆ m_iHit

◆ m_innerDifferenceVector

◆ m_oHit

◆ m_outerDifferenceVector