T3DLineFitter Class Reference

A class to fit a TTrackBase object to a 3D line. More...

#include <T3DLineFitter.h>

Inheritance diagram for T3DLineFitter:

Public Member Functions
	T3DLineFitter (const std::string &name)
	Constructor.
	T3DLineFitter (const std::string &name, bool m_sag, int m_prop, bool m_tof)
virtual	~T3DLineFitter ()
	Destructor.
void	dump (const std::string &message=std::string(""), const std::string &prefix=std::string("")) const
	dumps debug information.
virtual int	fit (TTrackBase &) const
virtual int	fit (TTrackBase &, float t0Offset) const
void	sag (bool)
void	propagation (int)
void	tof (bool)
Public Member Functions inherited from TMFitter
	TMFitter (const std::string &name)
	Constructor.
virtual	~TMFitter ()
	Destructor.
const std::string &	name (void) const
	returns name.
void	dump (const std::string &message=std::string(""), const std::string &prefix=std::string("")) const
virtual int	fit (TTrackBase &) const =0

Additional Inherited Members
Protected Member Functions inherited from TMFitter
void	fitDone (TTrackBase &) const
	sets the fitted flag. (Bad implementation)

Detailed Description

A class to fit a TTrackBase object to a 3D line.

Definition at line 41 of file T3DLineFitter.h.

Constructor & Destructor Documentation

T3DLineFitter() [1/2]

T3DLineFitter::T3DLineFitter

(

const std::string &

name

)

Constructor.

Definition at line 80 of file T3DLineFitter.cxx.

  : TMFitter(name),
//    _sag(true),_propagation(1),_tof(false){
    _sag(false),_propagation(0),_tof(true){   //Liuqg, tmp
 
}

T3DLineFitter() [2/2]

T3DLineFitter::T3DLineFitter	(	const std::string &	name,
		bool	m_sag,
		int	m_prop,
		bool	m_tof
	)

Definition at line 86 of file T3DLineFitter.cxx.

  : TMFitter(name),
    _sag(m_sag),_propagation(m_prop),_tof(m_tof){
}

~T3DLineFitter()

T3DLineFitter::~T3DLineFitter ( )

virtual

Destructor.

Definition at line 92 of file T3DLineFitter.cxx.

                              {
}

Member Function Documentation

dump()

void T3DLineFitter::dump	(	const std::string &	message = std::string(""),
		const std::string &	prefix = std::string("")
	)		const

dumps debug information.

fit() [1/2]

int T3DLineFitter::fit ( TTrackBase &  tb ) const

virtual

Implements TMFitter.

Definition at line 211 of file T3DLineFitter.cxx.

                                          {
  return fit(tb,0);
}

Referenced by fit().

fit() [2/2]

int T3DLineFitter::fit ( TTrackBase &  tb, float  t0Offset  ) const

virtual

Definition at line 215 of file T3DLineFitter.cxx.

                                                          {
 
  //std::cout<<"T3DLineFitter::fit  start"<<std::endl;
 
  //...Type check...
  if(tb.objectType() != Line3D) return TFitUnavailable;
  T3DLine& t = (T3DLine&) tb;
 
  //...Already fitted ?...
  if(t.fitted()) return TFitAlreadyFitted;
 
  //...Count # of hits...
  AList<TMLink> cores = t.cores();
  unsigned nCores = cores.length();
  unsigned nStereoCores = NStereoHits(cores);
 
  
  //...Check # of hits...
  bool flag2D = false;
  if ((nStereoCores == 0) && (nCores > 3)) flag2D = true;
  else if ((nStereoCores < 2) || (nCores - nStereoCores < 3))
    return TFitErrorFewHits;
 
  //...Move pivot to ORIGIN...
  const HepPoint3D pivot_bak = t.pivot();
  t.pivot(ORIGIN);
 
  //...Setup...
  Vector a(4),da(4);
  a = t.a();
  Vector dxda(4);
  Vector dyda(4);
  Vector dzda(4);
  Vector dDda(4);
  Vector dchi2da(4);
  SymMatrix d2chi2d2a(4,0);
  static const SymMatrix zero4(4,0);
  double chi2;
  double chi2Old = DBL_MAX;
  double factor = 1.0;
  int err = 0;
  SymMatrix e(2,0);
  Vector f(2);
 
  //...Fitting loop...
  unsigned nTrial = 0;
  while(nTrial < 100){
    
    //...Set up...
    chi2 = 0;
    for (unsigned j=0;j<4;j++) dchi2da[j]=0;
    d2chi2d2a=zero4;
 
    //...Loop with hits...
    unsigned i=0;
    while(TMLink* l = cores[i++]){
      const TMDCWireHit& h = *l->hit();
 
      //...Cal. closest points...
      t.approach(*l,_sag);
      const HepPoint3D& onTrack=l->positionOnTrack();
      const HepPoint3D& onWire=l->positionOnWire();
      unsigned leftRight = WireHitRight;
      if (onWire.cross(onTrack).z() < 0.) leftRight = WireHitLeft;
 
      //...Obtain drift distance and its error...
      double distance;
      double eDistance;
      drift(t, * l, t0Offset, distance, eDistance);
      l->drift(distance,0);
      l->drift(distance,1);
      l->dDrift(eDistance,0);
      l->dDrift(eDistance,1);
      double eDistance2 = eDistance * eDistance;
      //cout<<"distance: "<< distance << " eDistance: " << eDistance << endl;
 
      //...Residual...
      HepVector3D v = onTrack - onWire;
      double vmag = v.mag();
      double dDistance = vmag - distance;
 
      HepVector3D vw;
      //...dxda...
      this->dxda(*l, t, dxda, dyda, dzda, vw);
 
      //...Chi2 related...
      dDda = (vmag > 0.)
    ? ((v.x() * (1. - vw.x() * vw.x()) -
        v.y() * vw.x() * vw.y() - v.z() * vw.x() * vw.z())
       * dxda + 
       (v.y() * (1. - vw.y() * vw.y()) -
        v.z() * vw.y() * vw.z() - v.x() * vw.y() * vw.x())
       * dyda + 
       (v.z() * (1. - vw.z() * vw.z()) -
        v.x() * vw.z() * vw.x() - v.y() * vw.z() * vw.y())
       * dzda) / vmag : Vector(4,0);
      if (vmag <= 0.0) {
    std::cout << "    in fit " << onTrack << ", " << onWire;
    h.dump();
      }
      dchi2da += (dDistance / eDistance2) * dDda;
      d2chi2d2a += vT_times_v(dDda) / eDistance2;
      double pChi2 = dDistance * dDistance / eDistance2;
      chi2 += pChi2;
      
      //...Store results...
      l->update(onTrack, onWire, leftRight, pChi2);
    }
 
    //...Check condition...
    double change = chi2Old - chi2;
 
    if (fabs(change) < 1.0e-5) break;
    if (change < 0.) {
      a += factor * da; //recover
      factor *= 0.1;
    }else{
      chi2Old = chi2;
      if(flag2D){
    f = dchi2da.sub(1,2);
    e = d2chi2d2a.sub(1,2);
    f = solve(e,f);
    da[0]=f[0];
    da[1]=f[1];
    da[2]= 0;
    da[3]= 0;
      }else{
    //...Cal. helix parameters for next loop...
    da = solve(d2chi2d2a, dchi2da);
      }
    }
    a -= factor * da;
    t.a(a);
    ++nTrial;
  }
 
  //...Cal. error matrix...
  SymMatrix Ea(4,0);
  unsigned dim;
  if(flag2D){
    dim=2;
    SymMatrix Eb(3,0),Ec(3,0);
    Eb = d2chi2d2a.sub(1,3);
    Ec = Eb.inverse(err);
    Ea[0][0] = Ec[0][0];
    Ea[0][1] = Ec[0][1];
    Ea[0][2] = Ec[0][2];
    Ea[1][1] = Ec[1][1];
    Ea[1][2] = Ec[1][2];
    Ea[2][2] = Ec[2][2];
  }else{
    dim=4;
    Ea = d2chi2d2a.inverse(err);
  }
 
  //...Store information...
  if(! err){
    t.a(a);
    t.Ea(Ea);
    t._fitted = true;
    if (flag2D) err = T3DLine2DFit;
  }else{
    err = TFitFailed;
  }
 
  t._ndf = nCores - dim;
  t._chi2 = chi2;
 
  //...Recover pivot...
  t.pivot(pivot_bak);
 
  return err;
}

propagation()

void T3DLineFitter::propagation

(

int

_in

)

Definition at line 98 of file T3DLineFitter.cxx.

                                      {
  _propagation = _in;
}

sag()

void T3DLineFitter::sag

(

bool

_in

)

Definition at line 95 of file T3DLineFitter.cxx.

                               {
  _sag = _in;
}

tof()

void T3DLineFitter::tof

(

bool

_in

)

Definition at line 101 of file T3DLineFitter.cxx.

                               {
  _tof = _in;
}

---

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

• T3DLineFitter.h
• T3DLineFitter.cxx