FastVertexFit Class Reference

#include <FastVertexFit.h>

Public Member Functions
	~FastVertexFit ()
void	init ()
void	addTrack (const int number, const HepVector helix, const HepSymMatrix err)
bool	Fit ()
double	chisq () const
VertexParameter	vtx () const
HepVector	Vx () const
HepSymMatrix	Evx () const
HepVector	Pull () const

Static Public Member Functions
static FastVertexFit *	instance ()

Detailed Description

Definition at line 18 of file FastVertexFit.h.

Constructor & Destructor Documentation

~FastVertexFit()

FastVertexFit::~FastVertexFit

(

)

Definition at line 15 of file FastVertexFit.cxx.

{;}

Member Function Documentation

addTrack()

void FastVertexFit::addTrack	(	const int	number,
		const HepVector	helix,
		const HepSymMatrix	err )

Definition at line 29 of file FastVertexFit.cxx.

                                                                                            {
  int ifail;
  int ierr;
  //HepSymMatrix err0(5, 0); //inverse of err;
  //err0 = err.inverse(ifail);
  HepSymMatrix Wc(2, 0);
  Wc[0][0] = err[0][0];
  Wc[0][1] = Wc[1][0] = err[0][3];
  Wc[1][1] = err[3][3];
  Wc = Wc.inverse(ifail);
 
  HepVector p0(3, 0), v0(3, 0);
  double pxy = 1./fabs(helix[2]);
  p0[0] = 0 - pxy*sin(helix[1]); //px
  p0[1] = pxy*cos(helix[1]);     //py
  p0[2] = pxy * helix[4];        //pz
  v0[0] = helix[0]*cos(helix[1]);//x
  v0[1] = helix[0]*sin(helix[1]);//y
  v0[2] = helix[3];              //z  
 
  HepPoint3D vv0(v0[0], v0[1], v0[2]);
  double bField = VertexFitBField::instance()->getBFieldZRef();
 
  int charge = (helix[2]>0 ? +1 :-1);
  double a = alpha * bField * charge;
  double T0 = sqrt((p0[0]+a*p0[1])*(p0[0]+a*p0[1])+(p0[1]-a*p0[0])*(p0[1]-a*p0[0]));
 
  HepMatrix Dc(2, 3, 0);
  Dc[0][0] = (p0[1] - a*v0[0])/T0;
  Dc[0][1] = 0 - (p0[0] + a*v0[1])/T0;
  Dc[1][0] = 0 - (p0[2]/T0) * (p0[0] + a*v0[1])/T0;
  Dc[1][1] = 0 - (p0[2]/T0) * (p0[1] - a*v0[0])/T0;
  Dc[1][2] = 1;
 
  m_D.push_back(Dc);
  m_W.push_back(Wc);
 
  HepSymMatrix DTWD(3, 0);
  DTWD = Wc.similarity(Dc.T());
  HepVector qTrk(2, 0);
  qTrk[0] = helix[0];
  qTrk[1] = helix[3];
  //HepVector xp(3, 0);
  //xp = Dc.inverse(ierr) * qTrk;
  m_DTWD.push_back(DTWD);
  m_xp.push_back(v0);
}

Referenced by DQASelHadron::execute().

chisq()

double FastVertexFit::chisq ( ) const

inline

Definition at line 38 of file FastVertexFit.h.

{return m_chisq;}

Referenced by Fit().

Evx()

HepSymMatrix FastVertexFit::Evx ( ) const

inline

Definition at line 41 of file FastVertexFit.h.

{return m_Evx;}   

Fit()

bool FastVertexFit::Fit

(

)

Definition at line 77 of file FastVertexFit.cxx.

                        {
  bool fitResult = false;
 
  int ifail;
  HepSymMatrix total_DTWD(3, 0);
  HepVector total_xp(3, 0);
 
  for(int i = 0; i < m_DTWD.size(); i++) {
    total_DTWD += m_DTWD[i];  
    total_xp += m_DTWD[i]*m_xp[i]; 
  }
  m_Vx = total_DTWD.inverse(ifail) * total_xp;
  m_Evx = total_DTWD.inverse(ifail);
 
  double chisq = 0;
  for(int i = 0; i < m_xp.size(); i++) {
    double chi2 = (m_DTWD[i].similarity((m_xp[i] - m_Vx).T()))[0][0];  
    chisq += chi2;
  }
  m_chisq = chisq;
 
  fitResult = true;
  return fitResult;
}

Referenced by DQASelHadron::execute().

init()

void FastVertexFit::init

(

)

Definition at line 19 of file FastVertexFit.cxx.

                         {
  m_D.clear();
  m_W.clear();
  m_DTWD.clear();
  m_xp.clear();
  m_chisq = 999;
  m_Vx = HepVector(3, 0);
  m_Evx = HepSymMatrix(3,0);
}

Referenced by DQASelHadron::execute().

instance()

FastVertexFit * FastVertexFit::instance ( )

static

Definition at line 9 of file FastVertexFit.cxx.

                                        {
  if(m_pointer) return m_pointer;
  m_pointer = new FastVertexFit();
  return m_pointer;
}

Referenced by DQASelHadron::execute().

Pull()

HepVector FastVertexFit::Pull

(

)

const

Definition at line 102 of file FastVertexFit.cxx.

                                    {
  HepVector pull(3, 0);
  pull[0] = m_Vx[0]/sqrt(m_Evx[0][0]);
  pull[1] = m_Vx[1]/sqrt(m_Evx[1][1]);
  pull[2] = m_Vx[2]/sqrt(m_Evx[2][2]);
  return pull;
}

vtx()

VertexParameter FastVertexFit::vtx ( ) const

inline

Definition at line 39 of file FastVertexFit.h.

{return m_vtx_infit;}

Vx()

HepVector FastVertexFit::Vx ( ) const

inline

Definition at line 40 of file FastVertexFit.h.

{return m_Vx;}

Referenced by DQASelHadron::execute().

---

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

• FastVertexFit.h
• FastVertexFit.cxx