TrkDriftCircleMath::DCSLFitter Class Reference

#include <DCSLFitter.h>

Inheritance diagram for TrkDriftCircleMath::DCSLFitter:

Collaboration diagram for TrkDriftCircleMath::DCSLFitter:

Classes
struct	FitData

Public Member Functions
	DCSLFitter ()=default
virtual	~DCSLFitter ()=default
virtual bool	fit (Segment &result, const Line &line, const DCOnTrackVec &dcs, double t0Seed=-99999.) const
virtual bool	fit (Segment &result, const Line &line, const DCOnTrackVec &dcs, const HitSelection &selection, double t0Seed=-99999.) const

Detailed Description

Definition at line 17 of file Tracking/TrkUtilityPackages/TrkDriftCircleMath/TrkDriftCircleMath/DCSLFitter.h.

Constructor & Destructor Documentation

DCSLFitter()

TrkDriftCircleMath::DCSLFitter::DCSLFitter ( )

default

~DCSLFitter()

virtual TrkDriftCircleMath::DCSLFitter::~DCSLFitter ( )

virtualdefault

Member Function Documentation

fit() [1/2]

bool TrkDriftCircleMath::DCSLFitter::fit ( Segment & result, const Line & line, const DCOnTrackVec & dcs, const HitSelection & selection, double t0Seed = -99999. ) const

virtual

Reimplemented in TrkDriftCircleMath::MdtSegmentT0Fitter.

Definition at line 14 of file Tracking/TrkUtilityPackages/TrkDriftCircleMath/src/DCSLFitter.cxx.

                                                                 {
 
  unsigned int N = dcs.size();
 
  if (N < 2) {
    return false;
  }
 
  if (selection.size() != N) {
    return false;
  } else {
    int used(0);
    for (unsigned int i = 0; i < N; ++i) {
      if (selection[i] == 0)
        ++used;
    }
    if (used < 2) {
      return false;
    }
  }
 
  double S{0}, Sz{0}, Sy{0};
  double Zc{0}, Yc{0};
  // reserve enough space for hits
  std::vector<FitData> data;
  data.reserve(N);
  unsigned int ii = 0;
  for (const DCOnTrack& it : dcs) {
    FitData datum{};
    datum.y = it.y();
    datum.z = it.x();
    datum.r = std::abs(it.r());
    datum.w = std::pow(it.dr() > 0. ? 1. / it.dr() : 0., 2);
 
    if (selection[ii] == 0) {
      S += datum.w;
      Sz += datum.w * datum.z;
      Sy += datum.w * datum.y;
    }
    data.push_back(std::move(datum));
    ++ii;
  }
  if (not close_to_zero(S)){
    Zc = Sz / S;
    Yc = Sy / S;
  } else{
    throw std::runtime_error("DCSLFitter::fit: S is approx. zero!");
  }
 
  //
  //    shift hits
  //
  Sy = 0;
  Sz = 0;
  double Syy{0}, Szy{0}, Syyzz{0};
 
  for (unsigned int i = 0; i < N; ++i) {
    FitData& datum = data[i];
 
    datum.y -= Yc;
    datum.z -= Zc;
 
    if (selection[i])
      continue;
 
    datum.rw = datum.r * datum.w;
    datum.ryw = datum.rw * datum.y;
    datum.rzw = datum.rw * datum.z;
 
    Syy += datum.y * datum.y * datum.w;
    Szy += datum.y * datum.z * datum.w;
    Syyzz += (datum.y - datum.z) * (datum.y + datum.z) * datum.w;
  }
 
  unsigned int count{0};
  double R{0}, Ry{0}, Rz{0}, Att{0}, Add{S}, Bt{0}, Bd{0}, Stt{0}, Sd{0};
 
  double theta = line.phi();
  CxxUtils::sincos sc (theta);
 
  // make sure 0 <= theta < PI
  if (sc.sn < 0.0) {
    sc.sn = -sc.sn;
    sc.cs = -sc.cs;
  } else if (sc.sn == 0.0 && sc.cs < 0.0) {
    sc.cs = -sc.cs;
  }
  //
  // calculate shift
  double d = line.y0() + sc.apply (Zc, -Yc);
 
  while (count < 100) {
    R = Ry = Rz = 0;
 
    for (unsigned int i = 0; i < N; ++i) {
      if (selection[i])
        continue;
 
      FitData& datum = data[i];
 
      double dist = sc.apply (-datum.z, datum.y);;
      if (dist > d) {
        R -= datum.rw;
        Ry -= datum.ryw;
        Rz -= datum.rzw;
      } else {
        R += datum.rw;
        Ry += datum.ryw;
        Rz += datum.rzw;
      }
    }
    Att = Syy + sc.cs * (2 * sc.sn * Szy - sc.cs * Syyzz);
    Bt = -Szy + sc.cs * (sc.sn * Syyzz + 2 * sc.cs * Szy + Rz) + sc.sn * Ry;
    Bd = -S * d + R;
    if (Att == 0) {
      if (data.capacity() > 100) {
        data.reserve(100);
        result.dcs().reserve(100);
      }
      return false;
    }
    theta += Bt / Att;
    if (theta < 0.0)
      theta += M_PI;
    if (theta >= M_PI)
      theta -= M_PI;
    sc = CxxUtils::sincos (theta);
    sc.sn = std::abs(sc.sn);
    d = R / S;
    if (std::abs(Bt / Att) < 0.001 && std::abs(Bd / Add) < 0.001) {
      Stt = std::sqrt(1 / Att);
      Sd = std::sqrt(1 / Add);
      break;
    }
    ++count;
  }
  // Fit did not converge
  if (count >= 100) {
    return false;
  }
 
  double yl{0}, chi2{0};
 
  double dtheta = Stt;
  double dy0 = Sd;
 
  result.dcs().clear();
  result.clusters().clear();
  result.emptyTubes().clear();
 
  unsigned int nhits{0};
 
  // calculate predicted hit positions from track parameters
  result.dcs().reserve(N);
  for (unsigned int i = 0; i < N; ++i) {
    FitData& datum = data[i];
    yl = sc.apply (-datum.z, datum.y) - d;
    double dth = -sc.apply (datum.y, datum.z) * Stt;
    double errorResiduals = std::hypot(dth, Sd);
    double residuals = std::abs(yl) - datum.r;
    if (selection[i] == 0) {
      ++nhits;
      chi2 += residuals * residuals * datum.w;
    }
    result.dcs().emplace_back(dcs[i]);
    result.dcs().back().residual(residuals);
    result.dcs().back().errorTrack(errorResiduals);
  }
  if (nhits>=2){
    result.set(chi2, nhits - 2, dtheta, dy0);
    result.line().set(LocVec2D(Zc - sc.sn * d, Yc + sc.cs * d), theta);
  }
 
  return true;
}

fit() [2/2]

bool TrkDriftCircleMath::DCSLFitter::fit ( Segment & result, const Line & line, const DCOnTrackVec & dcs, double t0Seed = -99999. ) const

inlinevirtual

Reimplemented in TrkDriftCircleMath::MdtSegmentT0Fitter.

Definition at line 38 of file Tracking/TrkUtilityPackages/TrkDriftCircleMath/TrkDriftCircleMath/DCSLFitter.h.

                                                                   {
  HitSelection selection(dcs.size(), 0);
  return fit(result, line, dcs, selection);
}

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

• Tracking/TrkUtilityPackages/TrkDriftCircleMath/TrkDriftCircleMath/DCSLFitter.h
• Tracking/TrkUtilityPackages/TrkDriftCircleMath/src/DCSLFitter.cxx