KalmanCalculator.h

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//****************************************************************************
//*                   This file is part of PandaRoot.                        *
//*                                                                          *
//*            PandaRoot is distributed under the terms of the               *
//*              GNU General Public License (GPL) version 3,                 *
//*                 copied verbatim in the file "LICENSE".                   *
//*                                                                          *
//*  Copyright (C) 2006 - 2024 FAIR GmbH and copyright holders of PandaRoot  *
//*     The copyright holders are listed in the file "COPYRIGHTHOLDERS".     *
//*               The authors are listed in the file "AUTHORS".              *
//****************************************************************************

// ******************************************************
// DecayTreeFitter Package
// We thank the original author Wouter Hulsbergen
// (BaBar, LHCb) for providing the sources.
// http://arxiv.org/abs/physics/0503191v1 (2005)
// Adaptation & Development for PANDA: Ralf Kliemt (2015)
// ******************************************************
#ifndef KALMANCALCULATOR_H
#define KALMANCALCULATOR_H 1

#include "TVectorD.h"
#include "TMatrixD.h"
#include "TMatrixDSym.h"
#include "FitParams.h"
#include "ErrCode.h"
#include "Rtypes.h"

namespace DecayTreeFitter {

class KalmanCalculator {
 public:
  KalmanCalculator(){};
  virtual ~KalmanCalculator(){};

  ErrCode init(const TVectorD &value, const TMatrixD &G, const FitParams *fitparams, const TMatrixDSym &V, int weight = 1);
  void updatePar(FitParams *fitparams);
  void updatePar(const TVectorD &prediction, FitParams *fitparams);
  void updateCov(FitParams *fitparams);
  double chisq() const { return m_chisq; }

 private:
  int m_nconstraints; // dimension of the constraint
  int m_nparameters;  // dimension of the state
  const TVectorD *m_value;
  const TMatrixD *m_matrixG;
  TMatrixDSym m_matrixR;    // cov of residual
  TMatrixDSym m_matrixRinv; // inverse of cov of residual
  TMatrixD m_matrixK;       // kalman gain matrix
  double m_chisq;
  int m_ierr;
  // some temporary results
  TMatrixD m_matrixCGT;
  ClassDef(KalmanCalculator, 1)
};
} // namespace DecayTreeFitter

#endif