CbmRichRingFitterEllipseBase.h

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/* Copyright (C) 2009-2012 UGiessen/JINR-LIT, Giessen/Dubna
   SPDX-License-Identifier: GPL-3.0-only
   Authors: Semen Lebedev [committer] */
 
#ifndef CBM_RICH_RING_FITTER_ELLIPSE_BASE
#define CBM_RICH_RING_FITTER_ELLIPSE_BASE
 
#include "CbmRichRingFitterBase.h"
 
class CbmRichRingFitterEllipseBase : public CbmRichRingFitterBase {
 public:
  CbmRichRingFitterEllipseBase(){};
 
  virtual ~CbmRichRingFitterEllipseBase(){};
 
 protected:
  virtual void CalcChi2(CbmRichRingLight* ring)
  {
    int nofHits = ring->GetNofHits();
    if (nofHits <= 5) {
      ring->SetChi2(-1.);
      return;
    }
 
    double axisA = ring->GetAaxis();
    double axisB = ring->GetBaxis();
 
    if (axisA < axisB) {
      ring->SetChi2(-1.);
      return;
    }
 
    // calculate ellipse focuses
    double xf1 = ring->GetXF1();
    double yf1 = ring->GetYF1();
    double xf2 = ring->GetXF2();
    double yf2 = ring->GetYF2();
 
    // calculate chi2
    double chi2 = 0.;
    for (int iHit = 0; iHit < nofHits; iHit++) {
      double x = ring->GetHit(iHit).fX;
      double y = ring->GetHit(iHit).fY;
 
      double d1 = sqrt((x - xf1) * (x - xf1) + (y - yf1) * (y - yf1));
      double d2 = sqrt((x - xf2) * (x - xf2) + (y - yf2) * (y - yf2));
 
      chi2 += (d1 + d2 - 2. * axisA) * (d1 + d2 - 2. * axisA);
    }
    ring->SetChi2(chi2);
  }
 
  virtual void CalcChi2(double A, double B, double C, double D, double E, double F, CbmRichRingLight* ring)
  {
    int nofHits = ring->GetNofHits();
    if (nofHits <= 5) {
      ring->SetChi2(-1.);
      return;
    }
    double chi2 = 0.;
    for (int iHit = 0; iHit < nofHits; iHit++) {
      double x = ring->GetHit(iHit).fX;
      double y = ring->GetHit(iHit).fY;
 
      double d1 = fabs(A * x * x + B * x * y + C * y * y + D * x + E * y + F);
      double d2 = sqrt(pow(2 * A * x + B * y + D, 2) + pow(B * x + 2 * C * y + E, 2));
 
      chi2 += (d1 * d1) / (d2 * d2);
    }
    ring->SetChi2(chi2);
  }
};
 
#endif /* CBMRICHRINGFITTERELLIPSEBASEH */