#include <PRD_TruthTrajectorySelectorID.h>

Collaboration diagram for ThreePointCircle:

Public Member Functions
	ThreePointCircle (const std::vector< Amg::Vector3D > &vecPoints)
	The constructor from three points. More...

	~ThreePointCircle ()
	Destructor. More...

const Amg::Vector2D &	center () const
	center More...

const Amg::Translation3D *	frameTranslation () const
	Translation. More...

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.

62 { 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);
     
 }