ThreePointCircle Class Reference

#include <PRD_TruthTrajectorySelectorID.h>

Collaboration diagram for ThreePointCircle:

Public Member Functions
	ThreePointCircle (const std::vector< Amg::Vector3D > &vecPoints)
	The constructor from three points.
	~ThreePointCircle ()
	Destructor.
const Amg::Vector2D &	center () const
	center
const Amg::Translation3D *	frameTranslation () const
	Translation.
ThreePointCircle &	operator= (const ThreePointCircle &)=delete
	ThreePointCircle (const ThreePointCircle &)=delete
double	d0 () const
double	z0 () const
double	phi0 () const
double	eta () const
double	pT () const
double	radius () const

Private Member Functions
void	constructCircle (const Amg::Vector3D &, const Amg::Vector3D &, const Amg::Vector3D &)

Private Attributes
Amg::Translation3D *	m_translation
double	m_d0
double	m_z0
double	m_phi0
double	m_eta
double	m_pt
double	m_radius {}
Amg::Vector2D	m_center

Detailed Description

Definition at line 16 of file PRD_TruthTrajectorySelectorID.h.

Constructor & Destructor Documentation

ThreePointCircle() [1/2]

ThreePointCircle::ThreePointCircle

(

const std::vector< Amg::Vector3D > &

vecPoints

)

The constructor from three points.

Definition at line 42 of file PRD_TruthTrajectorySelectorID.cxx.

                                                                       :
    m_translation(nullptr), m_d0(0.), m_z0(0.), m_phi0(0.), m_eta(0.), m_pt(0.)
{
    if (posVec.size() <3)
        std::cout << "[WARNING] not enough points" << std::endl;
    else
        constructCircle(posVec[0],posVec[1],posVec[2]); 
}

~ThreePointCircle()

ThreePointCircle::~ThreePointCircle

(

)

Destructor.

Definition at line 51 of file PRD_TruthTrajectorySelectorID.cxx.

{
    delete m_translation;
}

ThreePointCircle() [2/2]

ThreePointCircle::ThreePointCircle ( const ThreePointCircle & )

delete

Member Function Documentation

center()

const Amg::Vector2D & ThreePointCircle::center ( ) const

inline

center

Definition at line 62 of file PRD_TruthTrajectorySelectorID.h.

{ return m_center; }

constructCircle()

void ThreePointCircle::constructCircle ( const Amg::Vector3D & p1, const Amg::Vector3D & p2, const Amg::Vector3D & p3 )

private

Definition at line 56 of file PRD_TruthTrajectorySelectorID.cxx.

                                           {
    
    // get the (x/y) coordinates of all points
  double translationX = m_translation ? -(m_translation->translation()).x() : 0.;
  double translationY = m_translation ? -(m_translation->translation()).y() : 0.;
    
  double bx = p1.x()+translationX; 
    double by = p1.y()+translationY;
  double cx = p2.x()+translationX;
    double cy = p2.y()+translationY;
  double dx = p3.x()+translationX;
    double dy = p3.y()+translationY;
    
  double temp = cx*cx+cy*cy;
 
    // prepare the matrix for the linear equation
  double bc = (bx*bx + by*by - temp)/2.0;
  double cd = (temp - dx*dx - dy*dy)/2.0;
  double det = (bx-cx)*(cy-dy)-(cx-dx)*(by-cy);
  //if (std::abs(det) < 1.0e-6) {
  //std::cout << "[WARNING] Determinant is close to 0 " << std::endl;
  //}
 
    // invert the determinant
  det = 1./det;
 
    // x / y coordinate of the center
  double cRx= (bc*(cy-dy)-cd*(by-cy))*det;
  double cRy = ((bx-cx)*cd-(cx-dx)*bc)*det;
 
    // get the center, radius and momentum
  m_center = Amg::Vector2D(cRx,cRy); 
  m_radius = sqrt((cRx-bx)*(cRx-bx)+(cRy-by)*(cRy-by));
    m_pt = m_radius*(0.3*2.);
 
    // transverse parameters
    m_d0 = std::sqrt(cRx*cRx+cRy*cRy)-m_radius;
 
    // longitudinal parameters
    double theta = 1./3*(p1.theta() + p2.theta() + p3.theta());
    double r1 = p1.perp();
    double z1 = p1.z();
    double deltaz = r1/tan(theta);
    m_z0 = z1 - deltaz;
    // eta
    m_eta = 1./3*(p1.eta() + p2.eta() + p3.eta());
    
  // get the point of closest approach
    Amg::Vector2D poca = -m_d0*m_center.unit();
 
  // find the closest measurement
    Amg::Vector2D closestMeasurement = p1.perp() < p2.perp() ? 
      Amg::Vector2D(p1.x(),p1.y()) : Amg::Vector2D(p2.x(),p2.y());
    if (p3.perp() < p1.perp()) closestMeasurement = Amg::Vector2D(p3.x(),p3.y());
 
  // phi0 is the most difficult one, two solution possible
    Amg::Vector2D directionOne(-cRy,cRx);
    Amg::Vector2D directionTwo(cRy,-cRx);
 
    // build difference vector closest measurement, poca
    Amg::Vector2D toFirstMeas(closestMeasurement-poca);
 
    // check with scalar product
    m_phi0 = directionOne.dot(toFirstMeas) > 0. ? directionOne.phi() : directionTwo.phi();
 
    // now sign d0
    Amg::Vector3D pocaDir(poca.x(),poca.y(),0.);
    Amg::Vector3D momDir(std::cos(m_phi0),std::sin(m_phi0),0.);
  double signD0 = pocaDir.cross(momDir).z() > 0. ? 1. : -1.;    
    m_d0 = signD0 * std::abs(m_d0);
        
    // update the center for the translation
    m_center += Amg::Vector2D(translationX,translationY);
    
}

d0()

double ThreePointCircle::d0 ( ) const

inline

Definition at line 55 of file PRD_TruthTrajectorySelectorID.h.

{ return m_d0; }

eta()

double ThreePointCircle::eta ( ) const

inline

Definition at line 58 of file PRD_TruthTrajectorySelectorID.h.

{ return m_eta; }

frameTranslation()

const Amg::Translation3D * ThreePointCircle::frameTranslation ( ) const

inline

Translation.

Definition at line 64 of file PRD_TruthTrajectorySelectorID.h.

{ return m_translation; }

operator=()

ThreePointCircle & ThreePointCircle::operator= ( const ThreePointCircle & )

delete

phi0()

double ThreePointCircle::phi0 ( ) const

inline

Definition at line 57 of file PRD_TruthTrajectorySelectorID.h.

{ return m_phi0; }

pT()

double ThreePointCircle::pT ( ) const

inline

Definition at line 59 of file PRD_TruthTrajectorySelectorID.h.

{ return m_pt; }

radius()

double ThreePointCircle::radius ( ) const

inline

Definition at line 60 of file PRD_TruthTrajectorySelectorID.h.

{ return m_radius; }

z0()

double ThreePointCircle::z0 ( ) const

inline

Definition at line 56 of file PRD_TruthTrajectorySelectorID.h.

{ return m_z0; }

Member Data Documentation

m_center

Amg::Vector2D ThreePointCircle::m_center

private

Definition at line 51 of file PRD_TruthTrajectorySelectorID.h.

m_d0

double ThreePointCircle::m_d0

private

Definition at line 49 of file PRD_TruthTrajectorySelectorID.h.

m_eta

double ThreePointCircle::m_eta

private

Definition at line 49 of file PRD_TruthTrajectorySelectorID.h.

m_phi0

double ThreePointCircle::m_phi0

private

Definition at line 49 of file PRD_TruthTrajectorySelectorID.h.

m_pt

double ThreePointCircle::m_pt

private

Definition at line 49 of file PRD_TruthTrajectorySelectorID.h.

m_radius

double ThreePointCircle::m_radius {}

private

Definition at line 50 of file PRD_TruthTrajectorySelectorID.h.

{};

m_translation

Amg::Translation3D* ThreePointCircle::m_translation

private

Definition at line 47 of file PRD_TruthTrajectorySelectorID.h.

m_z0

double ThreePointCircle::m_z0

private

Definition at line 49 of file PRD_TruthTrajectorySelectorID.h.

---

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

• PRD_TruthTrajectorySelectorID.h
• PRD_TruthTrajectorySelectorID.cxx