/**************************************************************************
 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
 *                                                                        *
 * Author: The ALICE Off-line Project.                                    *
 * Contributors are mentioned in the code where appropriate.              *
 *                                                                        *
 * Permission to use, copy, modify and distribute this software and its   *
 * documentation strictly for non-commercial purposes is hereby granted   *
 * without fee, provided that the above copyright notice appears in all   *
 * copies and that both the copyright notice and this permission notice   *
 * appear in the supporting documentation. The authors make no claims     *
 * about the suitability of this software for any purpose. It is          *
 * provided "as is" without express or implied warranty.                  *
 **************************************************************************/

/* $Id$ */

#include <stdlib.h> // for exit()
#include <Riostream.h>
#include <TClonesArray.h>
#include <TArrayD.h>
#include <TMatrixD.h>

#include "AliMUONTrackK.h"
#include "AliCallf77.h"
#include "AliMUON.h"
#include "AliMUONChamber.h"
#include "AliMUONEventReconstructor.h"
#include "AliMagF.h"
#include "AliMUONSegment.h"
#include "AliMUONHitForRec.h"
#include "AliMUONRawCluster.h"
#include "AliMUONTrackParam.h"
#include "AliRun.h"
#include "AliLog.h"

const Int_t AliMUONTrackK::fgkSize = 5;
const Int_t AliMUONTrackK::fgkNSigma = 6; 
const Double_t AliMUONTrackK::fgkChi2max = 25; 
const Int_t AliMUONTrackK::fgkTriesMax = 10000; 
const Double_t AliMUONTrackK::fgkEpsilon = 0.002; 

void mnvertLocalK(Double_t* a, Int_t l, Int_t m, Int_t n, Int_t& ifail);

ClassImp(AliMUONTrackK) // Class implementation in ROOT context

Int_t AliMUONTrackK::fgDebug = -1;
Int_t AliMUONTrackK::fgNOfPoints = 0; 
AliMUON* AliMUONTrackK::fgMUON = NULL;
AliMUONEventReconstructor* AliMUONTrackK::fgEventReconstructor = NULL; 
TClonesArray* AliMUONTrackK::fgHitForRec = NULL; 
//FILE *lun1 = fopen("window.dat","w");

  //__________________________________________________________________________
AliMUONTrackK::AliMUONTrackK()
  //AZ: TObject()
  : AliMUONTrack() 
{
  // Default constructor

  fgEventReconstructor = NULL; // pointer to event reconstructor
  fgMUON = NULL; // pointer to Muon module
  fgHitForRec = NULL; // pointer to points
  fgNOfPoints = 0; // number of points

  fStartSegment = NULL;
  fTrackHitsPtr = NULL;
  fNTrackHits = 0;
  fTrackPar = fTrackParNew = NULL;
  fCovariance = fWeight = NULL;
  fSkipHit = NULL;
  fParExtrap = fParFilter = fParSmooth = NULL;
  fCovExtrap = fCovFilter = NULL;
  fJacob = NULL; 
  fSteps = NULL; fNSteps = 0; 
  fChi2Array = NULL;
  fChi2Smooth = NULL;

  return;
}

  //__________________________________________________________________________
AliMUONTrackK::AliMUONTrackK(AliMUONEventReconstructor *EventReconstructor, TClonesArray *hitForRec)
  //AZ: TObject()
  : AliMUONTrack()
{
  // Constructor

  if (!EventReconstructor) return;
  fgEventReconstructor = EventReconstructor; // pointer to event reconstructor
  fgMUON = (AliMUON*) gAlice->GetModule("MUON"); // pointer to Muon module
  fgHitForRec = hitForRec; // pointer to points
  fgNOfPoints = fgHitForRec->GetEntriesFast(); // number of points

  fStartSegment = NULL;
  fTrackHitsPtr = NULL;
  fNTrackHits = 0;
  fChi2 = 0;
  fTrackPar = fTrackParNew = NULL;
  fCovariance = fWeight = NULL;
  fSkipHit = NULL;
  fParExtrap = fParFilter = fParSmooth = NULL;
  fCovExtrap = fCovFilter = NULL;
  fJacob = NULL; 
  fSteps = NULL; fNSteps = 0; 
  fChi2Array = NULL;
  fChi2Smooth = NULL;
}

  //__________________________________________________________________________
AliMUONTrackK::AliMUONTrackK(AliMUONSegment *segment)
  //AZ: TObject()
  : AliMUONTrack(segment, segment, fgEventReconstructor)
{
  // Constructor from a segment
  Double_t dX, dY, dZ;
  AliMUONHitForRec *hit1, *hit2;
  AliMUONRawCluster *clus;
  TClonesArray *rawclusters;

  fStartSegment = segment;
  fRecover = 0;
  fSkipHit = NULL;
  // Pointers to hits from the segment
  hit1 = segment->GetHitForRec1();
  hit2 = segment->GetHitForRec2();
  hit1->SetNTrackHits(hit1->GetNTrackHits()+1); // mark hit as being on track
  hit2->SetNTrackHits(hit2->GetNTrackHits()+1); // mark hit as being on track
  // check sorting in Z
  if (TMath::Abs(hit1->GetZ()) > TMath::Abs(hit2->GetZ())) {
    hit1 = hit2;
    hit2 = segment->GetHitForRec1();
  }
  // memory allocation for the TObjArray of pointers to reconstructed TrackHit's
  fTrackHitsPtr = new TObjArray(13);
  fNTrackHits = 2;
  fChi2 = 0;
  fBPFlag = kFALSE;
  fTrackPar = new TMatrixD(fgkSize,1); // track parameters
  fTrackParNew = new TMatrixD(fgkSize,1); // track parameters
  fCovariance = new TMatrixD(fgkSize,fgkSize); // covariance matrix
  fWeight = new TMatrixD(fgkSize,fgkSize); // weight matrix (inverse of covariance)

  // Fill array of track parameters
  if (hit1->GetChamberNumber() > 7) {
    // last tracking station
    (*fTrackPar)(0,0) = hit1->GetBendingCoor(); // y
    (*fTrackPar)(1,0) = hit1->GetNonBendingCoor(); // x
    fPosition = hit1->GetZ(); // z
    fTrackHitsPtr->Add(hit2); // add hit 2
    fTrackHitsPtr->Add(hit1); // add hit 1
    //AZ(Z->-Z) fTrackDir = -1;
    fTrackDir = 1;
  } else {
    // last but one tracking station
    (*fTrackPar)(0,0) = hit2->GetBendingCoor(); // y
    (*fTrackPar)(1,0) = hit2->GetNonBendingCoor(); // x
    fPosition = hit2->GetZ(); // z
    fTrackHitsPtr->Add(hit1); // add hit 1
    fTrackHitsPtr->Add(hit2); // add hit 2
    //AZ(Z->-Z) fTrackDir = 1;
    fTrackDir = -1;
  }
  dZ = hit2->GetZ() - hit1->GetZ();
  dY = hit2->GetBendingCoor() - hit1->GetBendingCoor();
  dX = hit2->GetNonBendingCoor() - hit1->GetNonBendingCoor();
  (*fTrackPar)(2,0) = TMath::ATan2(dY,dZ); // alpha
  (*fTrackPar)(3,0) = TMath::ATan2(dX,dZ/TMath::Cos((*fTrackPar)(2,0))); // beta
  (*fTrackPar)(4,0) = 1/fgEventReconstructor->GetBendingMomentumFromImpactParam(segment->GetBendingImpact()); // 1/Pt
  (*fTrackPar)(4,0) *= TMath::Cos((*fTrackPar)(3,0)); // 1/p
  // Evaluate covariance (and weight) matrix
  EvalCovariance(dZ);

  // For smoother
  fParExtrap = new TObjArray(15);
  fParFilter = new TObjArray(15);
  fCovExtrap = new TObjArray(15);
  fCovFilter = new TObjArray(15);
  fJacob = new TObjArray(15);
  fSteps = new TArrayD(15);
  fNSteps = 0;
  fChi2Array = new TArrayD(13);
  fChi2Smooth = NULL;
  fParSmooth = NULL;

  if (fgDebug < 0 ) return;
  cout << fgEventReconstructor->GetBendingMomentumFromImpactParam(segment->GetBendingImpact()) << " " << 1/(*fTrackPar)(4,0) << " ";
  if (fgEventReconstructor->GetRecTrackRefHits()) { 
    // from track ref. hits
    cout << ((AliMUONHitForRec*)((*fTrackHitsPtr)[0]))->GetTTRTrack() << "<-->" << ((AliMUONHitForRec*)((*fTrackHitsPtr)[1]))->GetTTRTrack() << " @ " << fStartSegment->GetHitForRec1()->GetChamberNumber() << endl;
  } else {
    // from raw clusters
    for (Int_t i=0; i<2; i++) {
      hit1 = (AliMUONHitForRec*) ((*fTrackHitsPtr)[i]);
      rawclusters = fgEventReconstructor->GetMUONData()->RawClusters(hit1->GetChamberNumber());
      clus = (AliMUONRawCluster*) rawclusters->UncheckedAt(hit1->GetHitNumber());
      cout << clus->GetTrack(1)-1;
      if (clus->GetTrack(2) != 0) cout << " " << clus->GetTrack(2)-1;
      if (i == 0) cout << " <--> ";
    }
    cout << " @ " << fStartSegment->GetHitForRec1()->GetChamberNumber() << endl;
  }
}

  //__________________________________________________________________________
AliMUONTrackK::~AliMUONTrackK()
{
  // Destructor

  if (fTrackHitsPtr) {
    delete fTrackHitsPtr; // delete the TObjArray of pointers to TrackHit's
    fTrackHitsPtr = NULL;
  }
  if (fTrackPar) {
    delete fTrackPar; delete fTrackParNew; delete fCovariance;
    delete fWeight;
  } 

  if (fSteps) delete fSteps; 
  if (fChi2Array) delete fChi2Array;
  if (fChi2Smooth) delete fChi2Smooth;
  if (fParSmooth) {fParSmooth->Delete(); delete fParSmooth; }
  // Delete only matrices not shared by several tracks
  if (!fParExtrap) return;

  Int_t id = 0;
  for (Int_t i=0; i<fNSteps; i++) {
    //if (fParExtrap->UncheckedAt(i)->GetUniqueID() > 1) 
    //  fParExtrap->UncheckedAt(i)->SetUniqueID(fParExtrap->RemoveAt(i)->GetUniqueID()-1);
    id = fParExtrap->UncheckedAt(i)->GetUniqueID();
    if (id > 1) { 
      fParExtrap->UncheckedAt(i)->SetUniqueID(id-1);
      fParExtrap->RemoveAt(i);
    }
    //if (fParFilter->UncheckedAt(i)->GetUniqueID() > 1) 
    //  fParFilter->UncheckedAt(i)->SetUniqueID(fParFilter->RemoveAt(i)->GetUniqueID()-1);
    id = fParFilter->UncheckedAt(i)->GetUniqueID();
    if (id > 1) { 
      fParFilter->UncheckedAt(i)->SetUniqueID(id-1);
      fParFilter->RemoveAt(i);
    }
    //if (fCovExtrap->UncheckedAt(i)->GetUniqueID() > 1) 
    //  fCovExtrap->UncheckedAt(i)->SetUniqueID(fCovExtrap->RemoveAt(i)->GetUniqueID()-1);
    id = fCovExtrap->UncheckedAt(i)->GetUniqueID();
    if (id > 1) { 
      fCovExtrap->UncheckedAt(i)->SetUniqueID(id-1);
      fCovExtrap->RemoveAt(i);
    }

    //if (fCovFilter->UncheckedAt(i)->GetUniqueID() > 1) 
    //  fCovFilter->UncheckedAt(i)->SetUniqueID(fCovFilter->RemoveAt(i)->GetUniqueID()-1);
    id = fCovFilter->UncheckedAt(i)->GetUniqueID();
    if (id > 1) { 
      fCovFilter->UncheckedAt(i)->SetUniqueID(id-1);
      fCovFilter->RemoveAt(i);
    }
    //if (fJacob->UncheckedAt(i)->GetUniqueID() > 1) 
    //  fJacob->UncheckedAt(i)->SetUniqueID(fJacob->RemoveAt(i)->GetUniqueID()-1);
    id = fJacob->UncheckedAt(i)->GetUniqueID();
    if (id > 1) { 
      fJacob->UncheckedAt(i)->SetUniqueID(id-1);
      fJacob->RemoveAt(i);
    }
  }
  /*
  for (Int_t i=0; i<fNSteps; i++) {
    if (fParExtrap->UncheckedAt(i)) ((TMatrixD*)fParExtrap->UncheckedAt(i))->Delete();
    if (fParFilter->UncheckedAt(i)) ((TMatrixD*)fParFilter->UncheckedAt(i))->Delete();
    if (fCovExtrap->UncheckedAt(i)) ((TMatrixD*)fCovExtrap->UncheckedAt(i))->Delete();
    cout << fCovFilter->UncheckedAt(i) << " " << (*fSteps)[i] << endl;
    if (fCovFilter->UncheckedAt(i)) ((TMatrixD*)fCovFilter->UncheckedAt(i))->Delete();
    if (fJacob->UncheckedAt(i)) ((TMatrixD*)fJacob->UncheckedAt(i))->Delete();
  }
  */
  fParExtrap->Delete(); fParFilter->Delete();
  fCovExtrap->Delete(); fCovFilter->Delete();
  fJacob->Delete();
  delete fParExtrap; delete fParFilter;
  delete fCovExtrap; delete fCovFilter;
  delete fJacob;
}

  //__________________________________________________________________________
AliMUONTrackK::AliMUONTrackK (const AliMUONTrackK& source)
  //AZ: TObject(source)
  : AliMUONTrack(source)
{
// Protected copy constructor
  AliFatal("Not implemented.");
}

  //__________________________________________________________________________
AliMUONTrackK & AliMUONTrackK::operator=(const AliMUONTrackK& source)
{
  // Assignment operator
  // Members
  if(&source == this) return *this;

  // base class assignement
  //AZ TObject::operator=(source);
  AliMUONTrack::operator=(source);

  fStartSegment = source.fStartSegment;
  fNTrackHits = source.fNTrackHits;
  fChi2 = source.fChi2;
  fPosition = source.fPosition;
  fPositionNew = source.fPositionNew;
  fTrackDir = source.fTrackDir;
  fBPFlag = source.fBPFlag;
  fRecover = source.fRecover;
  fSkipHit = source.fSkipHit;

  // Pointers
  fTrackHitsPtr = new TObjArray(*source.fTrackHitsPtr);
  //source.fTrackHitsPtr->Dump();
  //fTrackHitsPtr->Dump();
  
  fTrackPar = new TMatrixD(*source.fTrackPar); // track parameters
  fTrackParNew = new TMatrixD(*source.fTrackParNew); // track parameters
  fCovariance = new TMatrixD(*source.fCovariance); // covariance matrix
  fWeight = new TMatrixD(*source.fWeight); // weight matrix (inverse of covariance)

  // For smoother
  fParExtrap = new TObjArray(*source.fParExtrap);
  fParFilter = new TObjArray(*source.fParFilter);
  fCovExtrap = new TObjArray(*source.fCovExtrap);
  fCovFilter = new TObjArray(*source.fCovFilter);
  fJacob = new TObjArray(*source.fJacob);
  fSteps = new TArrayD(*source.fSteps);
  fNSteps = source.fNSteps;
  fChi2Array = NULL;
  if (source.fChi2Array) fChi2Array = new TArrayD(*source.fChi2Array);
  fChi2Smooth = NULL;
  fParSmooth = NULL;

  for (Int_t i=0; i<fParExtrap->GetEntriesFast(); i++) {
    fParExtrap->UncheckedAt(i)->SetUniqueID(fParExtrap->UncheckedAt(i)->GetUniqueID()+1);
    fParFilter->UncheckedAt(i)->SetUniqueID(fParFilter->UncheckedAt(i)->GetUniqueID()+1);
    fCovExtrap->UncheckedAt(i)->SetUniqueID(fCovExtrap->UncheckedAt(i)->GetUniqueID()+1);
    fCovFilter->UncheckedAt(i)->SetUniqueID(fCovFilter->UncheckedAt(i)->GetUniqueID()+1);
    fJacob->UncheckedAt(i)->SetUniqueID(fJacob->UncheckedAt(i)->GetUniqueID()+1);
  }
  return *this;
}

  //__________________________________________________________________________
void AliMUONTrackK::EvalCovariance(Double_t dZ)
{
  // Evaluate covariance (and weight) matrix for track candidate
  Double_t sigmaB, sigmaNonB, tanA, tanB, dAdY, rad, dBdX, dBdY;

  sigmaB = fgEventReconstructor->GetBendingResolution(); // bending resolution
  sigmaNonB = fgEventReconstructor->GetNonBendingResolution(); // non-bending resolution

  (*fWeight)(0,0) = sigmaB*sigmaB; // <yy>

  (*fWeight)(1,1) = sigmaNonB*sigmaNonB; // <xx>

  tanA = TMath::Tan((*fTrackPar)(2,0));
  dAdY = 1/(1+tanA*tanA)/dZ;
  (*fWeight)(2,2) = dAdY*dAdY*(*fWeight)(0,0)*2; // <aa>
  (*fWeight)(0,2) = dAdY*(*fWeight)(0,0); // <ya>
  (*fWeight)(2,0) = (*fWeight)(0,2);

  rad = dZ/TMath::Cos((*fTrackPar)(2,0));
  tanB = TMath::Tan((*fTrackPar)(3,0));
  dBdX = 1/(1+tanB*tanB)/rad;
  dBdY = 0; // neglect
  (*fWeight)(3,3) = dBdX*dBdX*(*fWeight)(1,1)*2; // <bb>
  (*fWeight)(1,3) = dBdX*(*fWeight)(1,1); // <xb>
  (*fWeight)(3,1) = (*fWeight)(1,3);

  //(*fWeight)(4,4) = ((*fTrackPar)(4,0)*0.2)*((*fTrackPar)(4,0)*0.2); // error 20%
  (*fWeight)(4,4) = ((*fTrackPar)(4,0)*0.5)*((*fTrackPar)(4,0)*0.5); // error 50%

  // check whether the Invert method returns flag if matrix cannot be inverted,
  // and do not calculate the Determinant in that case !!!!
  if (fWeight->Determinant() != 0) {
    // fWeight->Invert();
    Int_t ifailWeight;
    mnvertLocalK(&((*fWeight)(0,0)), fgkSize,fgkSize,fgkSize,ifailWeight);
  } else {
    AliWarning(" Determinant fWeight=0:");
  }
  return;
}

  //__________________________________________________________________________
Bool_t AliMUONTrackK::KalmanFilter(Int_t ichamBeg, Int_t ichamEnd, Bool_t Back, Double_t zDipole1, Double_t zDipole2)
{
  // Follows track through detector stations 
  Bool_t miss, success;
  Int_t ichamb, iFB, iMin, iMax, dChamb, ichambOK;
  Int_t ihit, firstIndx, lastIndx, currIndx;
  Double_t zEnd, dChi2;
  AliMUONHitForRec *hitAdd, *firstHit, *lastHit, *hit;
  AliMUONRawCluster *clus;
  TClonesArray *rawclusters;
  hit = 0; clus = 0; rawclusters = 0;

  miss = success = kTRUE;
  Int_t endOfProp = 0;
  iFB = (ichamEnd == ichamBeg) ? fTrackDir : TMath::Sign(1,ichamEnd-ichamBeg);
  iMin = TMath::Min(ichamEnd,ichamBeg);
  iMax = TMath::Max(ichamEnd,ichamBeg);
  ichamb = ichamBeg;
  ichambOK = ichamb;

  if (Back) {
    // backpropagation
    currIndx = 1; 
    if (((AliMUONHitForRec*)fTrackHitsPtr->First())->GetChamberNumber() != ichamb) currIndx = 0;
  } else if (fRecover) {
    hit = GetHitLastOk();
    currIndx = fTrackHitsPtr->IndexOf(hit);
    if (currIndx < 0) hit = fStartSegment->GetHitForRec1(); // for station 3
    Back = kTRUE;
    ichamb = hit->GetChamberNumber();
    if (hit == fSkipHit || fRecover == 2 && currIndx >= 0) {
      // start from the last point or outlier
      // remove the skipped hit
      fTrackHitsPtr->Remove(fSkipHit); // remove hit
      fNTrackHits --;
      fSkipHit->SetNTrackHits(fSkipHit->GetNTrackHits()-1); // unmark hit 
      if (fRecover == 1) {
	// recovery
	Back = kFALSE;
	fRecover = 0; 
	ichambOK = ((AliMUONHitForRec*)((*fTrackHitsPtr)[fNTrackHits-1]))->GetChamberNumber();
	//if (ichambOK >= 8 && ((AliMUONHitForRec*)((*fTrackHitsPtr)[0]))->GetChamberNumber() == 6) ichambOK = 6;
	currIndx = fgHitForRec->IndexOf(fSkipHit);
      } else {
	// outlier
	fTrackHitsPtr->Compress();
      }
    } // if (hit == fSkipHit)
    else if (currIndx < 0) currIndx = fTrackHitsPtr->IndexOf(hit);
  } // else if (fRecover) 
  else {
    // Get indices of the 1'st and last hits on the track candidate
    firstHit = (AliMUONHitForRec*) fTrackHitsPtr->First();
    lastHit = (AliMUONHitForRec*) fTrackHitsPtr->Last();
    firstIndx = fgHitForRec->IndexOf(firstHit);
    lastIndx = fgHitForRec->IndexOf(lastHit);
    currIndx = TMath::Abs (TMath::Max(firstIndx*iFB,lastIndx*iFB));
  }

  while (ichamb>=iMin && ichamb<=iMax) {
  // Find the closest hit in Z, not belonging to the current plane
    if (Back) {
      // backpropagation
      if (currIndx < fNTrackHits) {
	hitAdd = (AliMUONHitForRec*) fTrackHitsPtr->UncheckedAt(currIndx);
	zEnd = hitAdd->GetZ();
	//AZ(z->-z) } else zEnd = -9999;
      } else zEnd = 9999;
    } else {
      //AZ(Z->-Z) zEnd = -9999;
      zEnd = 9999;
      for (ihit=currIndx+iFB; ihit>=0 && ihit<fgNOfPoints; ihit+=iFB) {
	hitAdd = (AliMUONHitForRec*) ((*fgHitForRec)[ihit]);
	//if (TMath::Abs(hitAdd->GetZ()-fPosition) > 0.1) {
	if (TMath::Abs(hitAdd->GetZ()-fPosition) > 0.5) {
	  zEnd = hitAdd->GetZ();
	  currIndx = ihit;
	  break;
	}
      }
    }
    //AZ(Z->-Z) if (zEnd<-999 && ichamb==ichamEnd) endOfProp = 1; // end-of-propagation
    if (zEnd>999 && ichamb==ichamEnd) endOfProp = 1; // end-of-propagation
    else {
      // Check if there is a chamber without hits
      if (zEnd>999 || TMath::Abs(hitAdd->GetChamberNumber()-ichamb) > 1) {
	if (!Back && zEnd<999) currIndx -= iFB;
	ichamb += iFB;
	zEnd = (&(fgMUON->Chamber(ichamb)))->Z();
	miss = kTRUE;
      } else {
	ichamb = hitAdd->GetChamberNumber();
	miss = kFALSE;
      }
    }
    if (ichamb<iMin || ichamb>iMax) break;
    // Check for missing station 
    if (!Back) {
      dChamb = TMath::Abs(ichamb-ichambOK); 
      //cout << dChamb << " " << ichambOK << " " << fgNOfPoints << endl;
      Int_t dStatMiss = TMath::Abs (ichamb/2 - ichambOK/2);
      if (zEnd > 999) dStatMiss++;
      if (dStatMiss > 1) {
	// missing station - abandon track
	//cout << dChamb << " " << ichambOK << " " << fgNOfPoints << " " << 1/(*fTrackPar)(4,0) << endl;
	if (fgDebug >= 10) {
	  for (Int_t i1=0; i1<fgNOfPoints; i1++) {
	    cout << " Hit #" << ((AliMUONHitForRec*)((*fgHitForRec)[i1]))->GetChamberNumber() << " ";
	    cout << ((AliMUONHitForRec*)((*fgHitForRec)[i1]))->GetBendingCoor() << " ";
	    cout << ((AliMUONHitForRec*)((*fgHitForRec)[i1]))->GetNonBendingCoor() << " ";
	    cout << ((AliMUONHitForRec*)((*fgHitForRec)[i1]))->GetZ() << " " << " ";
	    cout << ((AliMUONHitForRec*)((*fgHitForRec)[i1]))->GetTTRTrack() << endl;
	  }
	  cout << endl;
	  cout << fNTrackHits << endl;
	  for (Int_t i1=0; i1<fNTrackHits; i1++) {
	    hit = (AliMUONHitForRec*) ((*fTrackHitsPtr)[i1]);
	    printf(" * %d %10.4f %10.4f %10.4f", 
	           hit->GetChamberNumber(), hit->GetBendingCoor(), 
		   hit->GetNonBendingCoor(), hit->GetZ());
	    if (fgEventReconstructor->GetRecTrackRefHits()) { 
	      // from track ref. hits
	      printf(" %3d %3d \n", hit->GetTrackRefSignal(), hit->GetTTRTrack());
	    } else {
	      // from raw clusters
	      rawclusters = fgEventReconstructor->GetMUONData()->RawClusters(hit->GetChamberNumber());
	      clus = (AliMUONRawCluster*) rawclusters->UncheckedAt(hit->GetHitNumber());
	      printf("%3d", clus->GetTrack(1)-1); 
	      if (clus->GetTrack(2) != 0) printf("%3d \n", clus->GetTrack(2)-1);
	      else printf("\n");
	    }
	  }
	} // if (fgDebug >= 10) 
	if (fNTrackHits>2 && fRecover==0) Recover(); // try to recover track later
	return kFALSE;
      } // if (dStatMiss > 1)
    } // if (!Back)
    if (endOfProp != 0) break;

    // propagate to the found Z

    // Check if track steps into dipole
    //AZ(z->-z) if (fPosition>zDipole2 && zEnd<zDipole2) {
    if (fPosition<zDipole2 && zEnd>zDipole2) {
      //LinearPropagation(zDipole2-zBeg); 
      ParPropagation(zDipole2); 
      MSThin(1); // multiple scattering in the chamber
      WeightPropagation(zDipole2, kTRUE); // propagate weight matrix
      fPosition = fPositionNew;
      *fTrackPar = *fTrackParNew; 
      //MagnetPropagation(zEnd); 
      ParPropagation(zEnd); 
      WeightPropagation(zEnd, kTRUE);
      fPosition = fPositionNew;
    } 
    // Check if track steps out of dipole
    //AZ(z->-z) else if (fPosition>zDipole1 && zEnd<zDipole1) {
    else if (fPosition<zDipole1 && zEnd>zDipole1) {
      //MagnetPropagation(zDipole1-zBeg); 
      ParPropagation(zDipole1); 
      MSThin(1); // multiple scattering in the chamber
      WeightPropagation(zDipole1, kTRUE);
      fPosition = fPositionNew;
      *fTrackPar = *fTrackParNew; 
      //LinearPropagation(zEnd-zDipole1); 
      ParPropagation(zEnd); 
      WeightPropagation(zEnd, kTRUE);
      fPosition = fPositionNew;
    } else {
      ParPropagation(zEnd);
      //MSThin(1); // multiple scattering in the chamber
      if (TMath::Abs(zEnd-fPosition) > 5) MSThin(1); // multiple scattering in the chamber
      WeightPropagation(zEnd, kTRUE);
      fPosition = fPositionNew;
    }

    // Add measurement
    if (fRecover != 0 && hitAdd == fSkipHit && !miss) {
      // recovered track - remove the hit
      miss = kTRUE;
      ichamb = fSkipHit->GetChamberNumber();
      // remove the skipped hit
      fTrackHitsPtr->Remove(fSkipHit); 
      fNTrackHits --;
      fSkipHit->SetNTrackHits(fSkipHit->GetNTrackHits()-1); // unmark hit 
      Back = kFALSE;
      fRecover =0;
      ichambOK = ((AliMUONHitForRec*)((*fTrackHitsPtr)[fNTrackHits-1]))->GetChamberNumber();
      currIndx = fgHitForRec->IndexOf(fSkipHit);
    }

    if (Back && !miss) {
      // backward propagator
      if (currIndx) {
	TMatrixD pointWeight(fgkSize,fgkSize);
	TMatrixD point(fgkSize,1);
	TMatrixD trackParTmp = point;
	point(0,0) = hitAdd->GetBendingCoor();
	point(1,0) = hitAdd->GetNonBendingCoor();
	pointWeight(0,0) = 1/hitAdd->GetBendingReso2();
	pointWeight(1,1) = 1/hitAdd->GetNonBendingReso2();
	TryPoint(point,pointWeight,trackParTmp,dChi2);
	*fTrackPar = trackParTmp;
	*fWeight += pointWeight; 
	//AZ(z->-z) if (fTrackDir < 0) AddMatrices (this, dChi2, hitAdd);
	if (fTrackDir > 0) AddMatrices (this, dChi2, hitAdd);
	fChi2 += dChi2; // Chi2
      } else *fTrackPar = *fTrackParNew; // adjust end point to the last hit
      if (ichamb==ichamEnd) break; 
      currIndx ++;
    } else {
      // forward propagator
      if (miss || !FindPoint(ichamb,zEnd,currIndx,iFB,hitAdd)) {
	// missing point
	*fTrackPar = *fTrackParNew; 
      } else {
	//add point
	fTrackHitsPtr->Add(hitAdd); // add hit
	fNTrackHits ++;
	hitAdd->SetNTrackHits(hitAdd->GetNTrackHits()+1); // mark hit as being on track
	ichambOK = ichamb;
	currIndx = fgHitForRec->IndexOf(hitAdd); // Check
      }
    }
  } // while
  if (fgDebug > 0) cout << fNTrackHits << " " << fChi2 << " " << 1/(*fTrackPar)(4,0) << " " << fPosition << endl;
  if (1/TMath::Abs((*fTrackPar)(4,0)) < fgEventReconstructor->GetMinBendingMomentum()) success = kFALSE; // p < p_min
  return success;
}

  //__________________________________________________________________________
void AliMUONTrackK::ParPropagation(Double_t zEnd)
{
  // Propagation of track parameters to zEnd
  Int_t iFB, nTries;
  Double_t dZ, step, distance, charge;
  Double_t vGeant3[7], vGeant3New[7];
  AliMUONTrackParam* trackParam = 0;
  nTries = 0;
  // First step using linear extrapolation
  dZ = zEnd - fPosition;
  fPositionNew = fPosition;
  *fTrackParNew = *fTrackPar;
  if (dZ == 0) return; //AZ ???
  iFB = (Int_t)TMath::Sign(Double_t(1.0),dZ);
  step = dZ/TMath::Cos((*fTrackPar)(2,0))/TMath::Cos((*fTrackPar)(3,0)); // linear estimate
  //AZ(z->-z) charge = iFB*TMath::Sign(Double_t(1.0),(*fTrackPar)(4,0));
  charge = -iFB*TMath::Sign(Double_t(1.0),(*fTrackPar)(4,0));
  SetGeantParam(vGeant3,iFB);

  // Check if overstep
  do {
    step = TMath::Abs(step);
    // Propagate parameters
    trackParam->ExtrapOneStepRungekutta(charge,step,vGeant3,vGeant3New);
    //    extrap_onestep_rungekutta(charge,step,vGeant3,vGeant3New);
    distance = zEnd - vGeant3New[2];
    step *= dZ/(vGeant3New[2]-fPositionNew);
    nTries ++;
  } while (distance*iFB < 0 && TMath::Abs(distance) > fgkEpsilon);

  GetFromGeantParam(vGeant3New,iFB);

  // Position adjustment (until within tolerance)
  while (TMath::Abs(distance) > fgkEpsilon) {
    dZ = zEnd - fPositionNew;
    iFB = (Int_t)TMath::Sign(Double_t(1.0),dZ);
    step = dZ/TMath::Cos((*fTrackParNew)(2,0))/TMath::Cos((*fTrackParNew)(3,0));
    step = TMath::Abs(step);
    SetGeantParam(vGeant3,iFB);
    do {
      // binary search
      // Propagate parameters
      //   extrap_onestep_rungekutta(charge,step,vGeant3,vGeant3New);
      trackParam->ExtrapOneStepRungekutta(charge,step,vGeant3,vGeant3New);

      distance = zEnd - vGeant3New[2];
      step /= 2;
      nTries ++;
      if (nTries > fgkTriesMax) {
	cout << " ***** ParPropagation: too many tries " << nTries << endl;
	AliFatal("Too many tries.");
      }
    } while (distance*iFB < 0);

    GetFromGeantParam(vGeant3New,iFB);
  }
  //cout << nTries << endl;
  return;
}
/*
  //__________________________________________________________________________
void AliMUONTrackK::WeightPropagation(void)
{
  // Propagation of the weight matrix
  // W = DtWD, where D is Jacobian 

  // !!! not implemented TMatrixD weight1(*fJacob,TMatrixD::kAtBA,*fWeight); // DtWD
  TMatrixD weight1(*fWeight,TMatrixD::kMult,*fJacob); // WD
  *fWeight = TMatrixD(*fJacob,TMatrixD::kTransposeMult,weight1); // DtWD
  return;
}
*/
  //__________________________________________________________________________
void AliMUONTrackK::WeightPropagation(Double_t zEnd, Bool_t smooth)
{
  // Propagation of the weight matrix
  // W = DtWD, where D is Jacobian 
  Int_t i, j;
  Double_t dPar;

  TMatrixD jacob(fgkSize,fgkSize);
  jacob = 0;

  // Save initial and propagated parameters
  TMatrixD trackPar0 = *fTrackPar;
  TMatrixD trackParNew0 = *fTrackParNew;
  Double_t savePosition = fPositionNew;

  // Get covariance matrix
  *fCovariance = *fWeight;
  // check whether the Invert method returns flag if matrix cannot be inverted,
  // and do not calculate the Determinant in that case !!!!
  if (fCovariance->Determinant() != 0) {
    //   fCovariance->Invert();
    Int_t ifailCov;
    mnvertLocalK(&((*fCovariance)(0,0)), fgkSize,fgkSize,fgkSize,ifailCov);
  } else {
    AliWarning(" Determinant fCovariance=0:");
  }

  // Loop over parameters to find change of the initial vs propagated ones
  zEnd = fPosition;
  fPosition = fPositionNew;
  for (i=0; i<fgkSize; i++) {
    dPar = TMath::Sqrt((*fCovariance)(i,i));
    *fTrackPar = trackParNew0;
    (*fTrackPar)(i,0) += dPar;
    ParPropagation(zEnd);
    for (j=0; j<fgkSize; j++) {
      jacob(j,i) = ((*fTrackParNew)(j,0)-trackPar0(j,0))/dPar;
    }
  }

  //jacob->Print();
  //trackParNew0.Print();
  //TMatrixD par1(jacob,TMatrixD::kMult,trackPar0); //
  //par1.Print();
  /*
  if (jacob.Determinant() != 0) {
    //  jacob.Invert();
  } else {
    cout << " ***** Warning in WeightPropagation: Determinant jacob=0:" << endl;
  }
  */
  TMatrixD weight1(*fWeight,TMatrixD::kMult,jacob); // WD
  *fWeight = TMatrixD(jacob,TMatrixD::kTransposeMult,weight1); // DtWD
  //fWeight->Print();

  // Restore initial and propagated parameters
  *fTrackPar = trackPar0;
  *fTrackParNew = trackParNew0;
  fPosition = zEnd;
  fPositionNew = savePosition;

  // Save for smoother
  if (!smooth) return; // do not use smoother
  //AZ(z->-z) if (fTrackDir > 0) return; // only for propagation towards int. point
  if (fTrackDir < 0) return; // only for propagation towards int. point
  TMatrixD *tmp = new TMatrixD(*fTrackParNew); // extrapolated parameters
  fParExtrap->Add(tmp);
  tmp->SetUniqueID(1);
  tmp = new TMatrixD(*fTrackParNew); // filtered parameters (if no measurement will be found)
  fParFilter->Add(tmp);
  tmp->SetUniqueID(1);
  *fCovariance = *fWeight;
  if (fCovariance->Determinant() != 0) {
    Int_t ifailCov;
    mnvertLocalK(&((*fCovariance)(0,0)), fgkSize,fgkSize,fgkSize,ifailCov);
  } else {
    AliWarning(" Determinant fCovariance=0:");
  }
  tmp = new TMatrixD(*fCovariance); // extrapolated covariance
  fCovExtrap->Add(tmp);
  tmp->SetUniqueID(1);
  tmp = new TMatrixD(*fCovariance); // filtered covariance (if no measurement will be found)
  fCovFilter->Add(tmp);
  tmp->SetUniqueID(1);
  tmp = new TMatrixD(jacob); // Jacobian
  tmp->Invert();
  fJacob->Add(tmp);
  tmp->SetUniqueID(1);
  if (fSteps->fN <= fNSteps) fSteps->Set(fSteps->fN+10);
  fSteps->AddAt(fPositionNew,fNSteps++); 
  if (fgDebug > 0) cout << " WeightPropagation " << fNSteps << " " << fPositionNew << endl;
  return;
}

  //__________________________________________________________________________
Bool_t AliMUONTrackK::FindPoint(Int_t ichamb, Double_t zEnd, Int_t currIndx, Int_t iFB, AliMUONHitForRec *&hitAdd)
{
  // Picks up point within a window for the chamber No ichamb 
  // Split the track if there are more than 1 hit
  Int_t ihit, nRecTracks;
  Double_t windowB, windowNonB, dChi2Tmp=0, dChi2, y, x, savePosition=0;
  TClonesArray *trackPtr;
  AliMUONHitForRec *hit, *hitLoop;
  AliMUONTrackK *trackK;

  Bool_t ok = kFALSE;
  //sigmaB = fgEventReconstructor->GetBendingResolution(); // bending resolution
  //sigmaNonB = fgEventReconstructor->GetNonBendingResolution(); // non-bending resolution
  *fCovariance = *fWeight;
  // check whether the Invert method returns flag if matrix cannot be inverted,
  // and do not calculate the Determinant in that case !!!!
  if (fCovariance->Determinant() != 0) {
    //  fCovariance->Invert();
      Int_t ifailCov;
      mnvertLocalK(&((*fCovariance)(0,0)), fgkSize,fgkSize,fgkSize,ifailCov);
  } else {
    AliWarning("Determinant fCovariance=0:");
  }
  //windowB = fgkNSigma*TMath::Sqrt((*fCovariance)(0,0)+sigmaB*sigmaB);
  //windowNonB = fgkNSigma*TMath::Sqrt((*fCovariance)(1,1)+sigmaNonB*sigmaNonB);
  // Loop over all hits and take hits from the chamber
  TMatrixD pointWeight(fgkSize,fgkSize);
  TMatrixD saveWeight = pointWeight;
  TMatrixD pointWeightTmp = pointWeight;
  TMatrixD point(fgkSize,1);
  TMatrixD trackPar = point;
  TMatrixD trackParTmp = point;
  Int_t nHitsOK = 0;
  Double_t zLast;
  zLast = ((AliMUONHitForRec*)fTrackHitsPtr->Last())->GetZ();

  for (ihit=currIndx; ihit>=0 && ihit<fgNOfPoints; ihit+=iFB) {
    hit = (AliMUONHitForRec*) ((*fgHitForRec)[ihit]);
    if (hit->GetChamberNumber() == ichamb) {
      //if (TMath::Abs(hit->GetZ()-zEnd) < 0.1) {
      if (TMath::Abs(hit->GetZ()-zEnd) < 0.5) {
        if (TMath::Abs(hit->GetZ()-zEnd) > 0.1) {
	  // adjust position: for multiple hits in the chamber
	  // (mostly (only?) for GEANT hits)
	  zEnd = hit->GetZ();
	  *fTrackPar = *fTrackParNew;
	  ParPropagation(zEnd);
	  WeightPropagation(zEnd, kTRUE);
	  fPosition = fPositionNew;
	  *fTrackPar = *fTrackParNew;
	  // Get covariance
	  *fCovariance = *fWeight;
	  if (fCovariance->Determinant() != 0) {
	    //fCovariance->Invert();
	    Int_t ifailCov;
	    mnvertLocalK(&((*fCovariance)(0,0)), fgkSize,fgkSize,fgkSize,ifailCov);
	  } else {
	    AliWarning("Determinant fCovariance=0:" );
	  }
	}
	y = hit->GetBendingCoor();
	x = hit->GetNonBendingCoor();
	windowB = fgkNSigma*TMath::Sqrt((*fCovariance)(0,0)+hit->GetBendingReso2());
	windowNonB = fgkNSigma*TMath::Sqrt((*fCovariance)(1,1)+hit->GetNonBendingReso2());
	//fprintf(lun1,"%3d %10.4f %10.4f %10.4f \n", ichamb, windowB, windowNonB, TMath::Abs(hit->GetZ()-zLast));

	windowB = TMath::Min (windowB,5.);
	/*
	if (TMath::Abs(hit->GetZ()-zLast) < 50) {
	  windowB = TMath::Min (windowB,0.5);
	  windowNonB = TMath::Min (windowNonB,3.);
	} else if (TMath::Abs(hit->GetZ()-zLast) < 200) {
	  windowB = TMath::Min (windowB,1.5);
	  windowNonB = TMath::Min (windowNonB,3.);
	} else if (TMath::Abs(hit->GetZ()-zLast) < 350) {
	  windowB = TMath::Min (windowB,4.);
	  windowNonB = TMath::Min (windowNonB,6.);
	}
	*/

	// Test
	/*
	if (TMath::Abs(hit->GetZ()-zLast) < 50) {
	  windowB = 5*TMath::Sqrt((*fCovariance)(0,0)+hit->GetBendingReso2());
	  windowNonB = 5*TMath::Sqrt((*fCovariance)(1,1)+hit->GetNonBendingReso2());
	} else {
	  windowB = fgkNSigma*TMath::Sqrt((*fCovariance)(0,0)+hit->GetBendingReso2());
	  windowNonB = fgkNSigma*TMath::Sqrt((*fCovariance)(1,1)+hit->GetNonBendingReso2());
	}
	*/

	//cout << TMath::Abs((*fTrackParNew)(0,0)-y) << " " << windowB << " " << TMath::Abs((*fTrackParNew)(1,0)-x) << " " << windowNonB << " " << zEnd << endl;
	if (TMath::Abs((*fTrackParNew)(0,0)-y) <= windowB &&
	    TMath::Abs((*fTrackParNew)(1,0)-x) <= windowNonB) {
	//if (TMath::Abs((*fTrackParNew)(0,0)-y) <= windowB &&
	  //    TMath::Abs((*fTrackParNew)(1,0)-x) <= windowNonB &&
	  //  hit->GetTrackRefSignal() == 1) { // just for test
	  // Vector of measurements and covariance matrix
	  point.Zero();
	  point(0,0) = y;
	  point(1,0) = x;
	  pointWeight(0,0) = 1/hit->GetBendingReso2();
	  pointWeight(1,1) = 1/hit->GetNonBendingReso2();
	  TryPoint(point,pointWeight,trackPar,dChi2);
	  if (TMath::Abs(1./(trackPar)(4,0)) < fgEventReconstructor->GetMinBendingMomentum()) continue; // p < p_min - next hit
	  ok = kTRUE;
	  nHitsOK++;
	  //if (nHitsOK > -1) {
	  if (nHitsOK == 1) {
	    // Save current members
	    saveWeight = *fWeight;
	    savePosition = fPosition;
	    // temporary storage for the current track
	    dChi2Tmp = dChi2;
	    trackParTmp = trackPar;
	    pointWeightTmp = pointWeight;
	    hitAdd = hit;
	  } else {
	    // branching: create a new track
	    trackPtr = fgEventReconstructor->GetRecTracksPtr();
	    nRecTracks = fgEventReconstructor->GetNRecTracks();
	    trackK = new ((*trackPtr)[nRecTracks]) AliMUONTrackK(NULL, NULL); 
	    *trackK = *this;
	    fgEventReconstructor->SetNRecTracks(nRecTracks+1);
	    if (fgDebug > 0) cout << " ******** New track: " << ichamb << " " << hit->GetTTRTrack() << " " << 1/(trackPar)(4,0) << " " << hit->GetBendingCoor() << " " << hit->GetNonBendingCoor() << " " << fNTrackHits << " " << nRecTracks << endl;
	    trackK->fRecover = 0;
	    *(trackK->fTrackPar) = trackPar;
	    *(trackK->fWeight) += pointWeight; 
	    trackK->fChi2 += dChi2;
	    // Check
	    /*
	    *(trackK->fCovariance) = *(trackK->fWeight);
	    if (trackK->fCovariance->Determinant() != 0) {
	      Int_t ifailCov;
	      mnvertLocalK(&((*(trackK->fCovariance))(0,0)), fgkSize,fgkSize,fgkSize,ifailCov);
	    }
	    cout << (*(trackK->fCovariance))(0,0) << " " << (*(trackK->fCovariance))(1,1) << " " << (*fCovariance)(0,0) << " " << (*fCovariance)(1,1) << endl;
	    */
	    // Add filtered matrices for the smoother
	    //AZ(z->-z) if (fTrackDir < 0) {
	    if (fTrackDir > 0) {
	      if (nHitsOK > 2) { // check for position adjustment
		for (Int_t i=trackK->fNSteps-1; i>=0; i--) {
		  if (TMath::Abs(hit->GetZ()-(*trackK->fSteps)[i]) > 0.1) {
		  //if (TMath::Abs(hit->GetZ()-(trackK->fSteps)[i]) > 0.1) {
		    RemoveMatrices(trackK);
		    cout << " *** Position adjustment 1 " << hit->GetZ() << " " 
                         << (*trackK->fSteps)[i] << endl;
		    AliFatal("Position adjustment 1.");
		  }
		  else break;
		}
	      }
	      AddMatrices (trackK, dChi2, hit);
	    }
	    // Mark hits as being on 2 tracks
	    for (Int_t i=0; i<fNTrackHits; i++) {
	      hitLoop = (AliMUONHitForRec*) ((*fTrackHitsPtr)[i]);
	      hitLoop->SetNTrackHits(hitLoop->GetNTrackHits()+1); 
	      if (fgDebug >=10) {
		cout << " ** ";
		cout << hitLoop->GetChamberNumber() << " ";
		cout << hitLoop->GetBendingCoor() << " ";
		cout << hitLoop->GetNonBendingCoor() << " ";
		cout << hitLoop->GetZ() << " " << " ";
		cout << hitLoop->GetTrackRefSignal() << " " << " ";
		cout << hitLoop->GetTTRTrack() << endl;
		printf(" ** %d %10.4f %10.4f %10.4f %d %d \n", 
		       hitLoop->GetChamberNumber(), hitLoop->GetBendingCoor(), 
		       hitLoop->GetNonBendingCoor(), hitLoop->GetZ(), 
		       hitLoop->GetTrackRefSignal(), hitLoop->GetTTRTrack());
	      }
	    }
	    //add point
	    trackK->fTrackHitsPtr->Add(hit); // add hit
	    trackK->fNTrackHits ++;
	    hit->SetNTrackHits(hit->GetNTrackHits()+1); // mark hit as being on track
	    if (ichamb == 9) {
	      // the last chamber
	      //AZ(z->-z) trackK->fTrackDir = -1;
	      trackK->fTrackDir = 1;
	      trackK->fBPFlag = kTRUE; 
	    }
	  }
	}
      }
    } else break; // different chamber
  } // for (ihit=currIndx;
  if (ok) {
    // Restore members
    *fTrackPar = trackParTmp;
    *fWeight = saveWeight;
    *fWeight += pointWeightTmp; 
    fChi2 += dChi2Tmp; // Chi2
    fPosition = savePosition;
    // Add filtered matrices for the smoother
    //AZ(z->-z) if (fTrackDir < 0) {
    if (fTrackDir > 0) {
      for (Int_t i=fNSteps-1; i>=0; i--) {
	if (TMath::Abs(fPosition-(*fSteps)[i]) > 0.1) {
	//if (TMath::Abs(fPosition-fSteps[i]) > 0.1) {
	  RemoveMatrices(this);
	  if (fgDebug > 1) cout << " *** Position adjustment 2 " << fPosition << " " << (*fSteps)[i] << endl;
	}
	else break;
      } // for (Int_t i=fNSteps-1;
      AddMatrices (this, dChi2Tmp, hitAdd);
      /*
      if (nHitsOK > 1) {
	for (Int_t i=0; i<fNSteps; i++) cout << (*fSteps)[i] << " "; cout << endl;
	for (Int_t i=0; i<trackK->fNSteps; i++) cout << (*trackK->fSteps)[i] << " "; cout << endl;
      }
      */
    } // if (fTrackDir > 0)
  }
  return ok;
}

  //__________________________________________________________________________
void AliMUONTrackK::TryPoint(TMatrixD &point, const TMatrixD &pointWeight, TMatrixD &trackParTmp, Double_t &dChi2)
{
  // Adds a measurement point (modifies track parameters and computes
  // change of Chi2)

  // Solving linear system (W+U)p' = U(m-p) + (W+U)p
  TMatrixD wu = *fWeight;
  wu += pointWeight; // W+U
  trackParTmp = point;
  trackParTmp -= *fTrackParNew; // m-p
  TMatrixD right(pointWeight,TMatrixD::kMult,trackParTmp); // U(m-p)
  TMatrixD right1(wu,TMatrixD::kMult,*fTrackParNew); // (W+U)p
  right += right1; // U(m-p) + (W+U)p

  // check whether the Invert method returns flag if matrix cannot be inverted,
  // and do not calculate the Determinant in that case !!!!
  if (wu.Determinant() != 0) {
    //  wu.Invert();
     Int_t ifailWU;
      mnvertLocalK(&((wu)(0,0)), fgkSize,fgkSize,fgkSize,ifailWU);
  } else {
    AliWarning("Determinant wu=0:");
  }
  trackParTmp = TMatrixD(wu,TMatrixD::kMult,right); 

  right1 = trackParTmp;
  right1 -= point; // p'-m
  point = trackParTmp;
  point -= *fTrackParNew; // p'-p
  right = TMatrixD(*fWeight,TMatrixD::kMult,point); // W(p'-p)
  TMatrixD value(point,TMatrixD::kTransposeMult,right); // (p'-p)'W(p'-p)
  dChi2 = value(0,0);
  right = TMatrixD(pointWeight,TMatrixD::kMult,right1); // U(p'-m)
  value = TMatrixD(right1,TMatrixD::kTransposeMult,right); // (p'-m)'U(p'-m)
  dChi2 += value(0,0);
  return;
}

  //__________________________________________________________________________
void AliMUONTrackK::MSThin(Int_t sign)
{
  // Adds multiple scattering in a thin layer (only angles are affected)
  Double_t cosAlph, cosBeta, momentum, velo, path, theta0;

  // check whether the Invert method returns flag if matrix cannot be inverted,
  // and do not calculate the Determinant in that case !!!!
  if (fWeight->Determinant() != 0) {
    //fWeight->Invert(); // covariance

    Int_t ifailWeight;
    mnvertLocalK(&((*fWeight)(0,0)), fgkSize,fgkSize,fgkSize,ifailWeight);
  } else {
    AliWarning("Determinant fWeight=0:");
  }

  cosAlph = TMath::Cos((*fTrackParNew)(2,0));
  cosBeta = TMath::Cos((*fTrackParNew)(3,0));
  momentum = 1/(*fTrackParNew)(4,0); // particle momentum
  //velo = momentum/TMath::Sqrt(momentum*momentum+muonMass*muonMass); // velocity/c for muon hypothesis
  velo = 1; // relativistic
  path = TMath::Abs(fgEventReconstructor->GetChamberThicknessInX0()/cosAlph/cosBeta); // path length
  theta0 = 0.0136/velo/momentum*TMath::Sqrt(path)*(1+0.038*TMath::Log(path)); // projected scattering angle

  (*fWeight)(2,2) += sign*theta0/cosBeta*theta0/cosBeta; // alpha
  (*fWeight)(3,3) += sign*theta0*theta0; // beta
  //fWeight->Invert(); // weight

  Int_t ifailWeight;
  mnvertLocalK(&((*fWeight)(0,0)), fgkSize,fgkSize,fgkSize,ifailWeight);
  return;
}

  //__________________________________________________________________________
void AliMUONTrackK::StartBack(void)
{
  // Starts backpropagator
  
  fBPFlag = kTRUE;
  fChi2 = 0;
  for (Int_t i=0; i<fgkSize; i++) {
    for (Int_t j=0; j<fgkSize; j++) {
      if (j==i) (*fWeight)(i,i) /= 100;
      //if (j==i) (*fWeight)(i,i) /= fNTrackHits*fNTrackHits;
      else (*fWeight)(j,i) = 0;
    }
  }
  // Sort hits on track in descending order in abs(z)
  SortHits(0, fTrackHitsPtr);
}

  //__________________________________________________________________________
void AliMUONTrackK::SortHits(Int_t iflag, TObjArray *array)
{
  // Sort hits in Z if the seed segment in the last but one station
  // (if iflag==0 in descending order in abs(z), if !=0 - unsort)
  
  if (iflag && ((AliMUONHitForRec*)(array->UncheckedAt(0)))->GetChamberNumber() == 6) return;
  Double_t z = 0, zmax = TMath::Abs(((AliMUONHitForRec*)(array->UncheckedAt(0)))->GetZ());
  Int_t i = 1, entries = array->GetEntriesFast(); 
  for ( ; i<entries; i++) {
    if (iflag) {
      if (((AliMUONHitForRec*)(array->UncheckedAt(i)))->GetChamberNumber() == 6) break;
    } else {
      z = TMath::Abs(((AliMUONHitForRec*)(array->UncheckedAt(i)))->GetZ());
      if (z < zmax) break;
      zmax = z;
      if (fgDebug >= 10) cout << " " << zmax << " " << z << " " << i << endl;
    }
  }
  if (!iflag) i--;
  for (Int_t j=0; j<=(i-1)/2; j++) {
    TObject *hit = array->UncheckedAt(j);
    array->AddAt(array->UncheckedAt(i-j),j);
    array->AddAt(hit,i-j);
  }
  if (fgDebug >= 10) {
    for (i=0; i<entries; i++) 
      cout << ((AliMUONHitForRec*)(array->UncheckedAt(i)))->GetZ() << " ";
    cout << " - Sort" << endl;
  }
}

  //__________________________________________________________________________
void AliMUONTrackK::SetGeantParam(Double_t *VGeant3, Int_t iFB)
{
  // Set vector of Geant3 parameters pointed to by "VGeant3"
  // from track parameters 

  VGeant3[0] = (*fTrackParNew)(1,0); // X
  VGeant3[1] = (*fTrackParNew)(0,0); // Y
  VGeant3[2] = fPositionNew; // Z
  //AZ(z->-z) VGeant3[3] = iFB*TMath::Sin((*fTrackParNew)(3,0)); // Px/Ptot
  //AZ)z->-z) VGeant3[4] = iFB*TMath::Cos((*fTrackParNew)(3,0))*TMath::Sin((*fTrackParNew)(2,0)); // Py/Ptot
  VGeant3[3] = -iFB*TMath::Sin((*fTrackParNew)(3,0)); // Px/Ptot
  VGeant3[4] = -iFB*TMath::Cos((*fTrackParNew)(3,0))*TMath::Sin((*fTrackParNew)(2,0)); // Py/Ptot
  VGeant3[5] = iFB*TMath::Sqrt(1.0-VGeant3[3]*VGeant3[3]-VGeant3[4]*VGeant3[4]); // Pz/Ptot
  VGeant3[6] = 1/TMath::Abs((*fTrackParNew)(4,0)); // Ptot
}

  //__________________________________________________________________________
void AliMUONTrackK::GetFromGeantParam(Double_t *VGeant3, Int_t iFB)
{
  // Get track parameters from vector of Geant3 parameters pointed 
  // to by "VGeant3"

  fPositionNew = VGeant3[2]; // Z
  (*fTrackParNew)(0,0) = VGeant3[1]; // Y 
  (*fTrackParNew)(1,0) = VGeant3[0]; // X
  //AZ(z->-z) (*fTrackParNew)(3,0) = TMath::ASin(iFB*VGeant3[3]); // beta
  //AZ(z->-z) (*fTrackParNew)(2,0) = TMath::ASin(iFB*VGeant3[4]/TMath::Cos((*fTrackParNew)(3,0))); // alpha
  (*fTrackParNew)(3,0) = TMath::ASin(-iFB*VGeant3[3]); // beta
  (*fTrackParNew)(2,0) = TMath::ASin(iFB*VGeant3[4]/TMath::Cos((*fTrackParNew)(3,0))) - TMath::Pi(); // alpha
  (*fTrackParNew)(4,0) = 1/VGeant3[6]*TMath::Sign(Double_t(1.0),(*fTrackPar)(4,0)); // 1/Ptot
}

  //__________________________________________________________________________
void AliMUONTrackK::SetTrackQuality(Int_t iChi2)
{
  // Computes "track quality" from Chi2 (if iChi2==0) or vice versa

  if (fChi2 > 500) {
    cout << " ***** Too high Chi2: " << fChi2 << endl;
    fChi2 = 500;
  }
  if (iChi2 == 0) fChi2 = fNTrackHits + (500.-fChi2)/501;
  else fChi2 = 500 - (fChi2-fNTrackHits)*501;
}

  //__________________________________________________________________________
Int_t AliMUONTrackK::Compare(const TObject* trackK) const
{
  // "Compare" function to sort with decreasing "track quality".
  // Returns +1 (0, -1) if quality of current track
  // is smaller than (equal to, larger than) quality of trackK

  if (fChi2 < ((AliMUONTrackK*)trackK)->fChi2) return(+1);
  else if (fChi2 == ((AliMUONTrackK*)trackK)->fChi2) return(0);
  else return(-1);
}

  //__________________________________________________________________________
Bool_t AliMUONTrackK::KeepTrack(AliMUONTrackK* track0) const
{
  // Check whether or not to keep current track 
  // (keep, if it has less than half of common hits with track0)
  Int_t hitsInCommon, nHits0, i, j, nTrackHits2;
  AliMUONHitForRec *hit0, *hit1;

  hitsInCommon = 0;
  nHits0 = track0->fNTrackHits;
  nTrackHits2 = fNTrackHits/2;

  for (i=0; i<nHits0; i++) {
    // Check if hit belongs to several tracks
    hit0 = (AliMUONHitForRec*) (*track0->fTrackHitsPtr)[i]; 
    if (hit0->GetNTrackHits() == 1) continue; 
    for (j=0; j<fNTrackHits; j++) {
      hit1 = (AliMUONHitForRec*) (*fTrackHitsPtr)[j]; 
      if (hit1->GetNTrackHits() == 1) continue; 
      if (hit0 == hit1) {
	hitsInCommon++;
	if (hitsInCommon >= nTrackHits2) return kFALSE;
	break;
      }
    } // for (j=0; 
  } // for (i=0; 
  return kTRUE;
}

  //__________________________________________________________________________
void AliMUONTrackK::Kill(void)
{
  // Kill track candidate
  Int_t i;
  AliMUONHitForRec *hit;

  if (fTrackHitsPtr) {
    // Remove track mark from hits
    for (i=0; i<fNTrackHits; i++) {
      hit = (AliMUONHitForRec*) (*fTrackHitsPtr)[i]; 
      hit->SetNTrackHits(hit->GetNTrackHits()-1); 
    }
  }
  fgEventReconstructor->GetRecTracksPtr()->Remove(this);
}

  //__________________________________________________________________________
void AliMUONTrackK::FillMUONTrack(void)
{
  // Compute track parameters at hit positions (as for AliMUONTrack)

  // Set number of hits per track
  ((AliMUONTrack*)this)->SetNTrackHits(fNTrackHits);

  // Set track parameters at vertex
  AliMUONTrackParam trackParam;
  SetTrackParam(&trackParam, fTrackPar, fPosition);
  ((AliMUONTrack*)this)->SetTrackParamAtVertex(&trackParam);

  // Set track parameters at hits
  for (Int_t i = fNTrackHits-1; i>=0; i--) {
    if ((*fChi2Smooth)[i] < 0) {
      // Propagate through last chambers
      trackParam.ExtrapToZ(((AliMUONHitForRec*)((*fTrackHitsPtr)[i]))->GetZ());
    } else {
      // Take saved info
      SetTrackParam(&trackParam, (TMatrixD*)fParSmooth->UncheckedAt(i), ((AliMUONHitForRec*)((*fTrackHitsPtr)[i]))->GetZ());
    }
    ((AliMUONTrack*)this)->AddTrackParamAtHit(&trackParam); 
  }
}

  //__________________________________________________________________________
void AliMUONTrackK::SetTrackParam(AliMUONTrackParam *trackParam, TMatrixD *par, Double_t z)
{
  // Fill AliMUONTrackParam object

  trackParam->SetBendingCoor((*par)(0,0));
  trackParam->SetNonBendingCoor((*par)(1,0));
  trackParam->SetBendingSlope(TMath::Tan((*par)(2,0)));
  trackParam->SetNonBendingSlope(TMath::Tan((*par)(3,0))/TMath::Cos((*par)(2,0)));
  trackParam->SetInverseBendingMomentum((*par)(4,0)/TMath::Cos((*par)(3,0)));
  trackParam->SetZ(z);
}

  //__________________________________________________________________________
void AliMUONTrackK::Branson(void)
{
  // Propagates track to the vertex thru absorber using Branson correction
  // (makes use of the AliMUONTrackParam class)
 
  AliMUONTrackParam *trackParam = new AliMUONTrackParam();
  /*
  trackParam->SetBendingCoor((*fTrackPar)(0,0));
  trackParam->SetNonBendingCoor((*fTrackPar)(1,0));
  trackParam->SetBendingSlope(TMath::Tan((*fTrackPar)(2,0)));
  trackParam->SetNonBendingSlope(TMath::Tan((*fTrackPar)(3,0))/TMath::Cos((*fTrackPar)(2,0)));
  trackParam->SetInverseBendingMomentum((*fTrackPar)(4,0)/TMath::Cos((*fTrackPar)(3,0)));
  trackParam->SetZ(fPosition);
  */
  SetTrackParam(trackParam, fTrackPar, fPosition);

  trackParam->ExtrapToVertex(Double_t(0.), Double_t(0.), Double_t(0.));

  (*fTrackPar)(0,0) = trackParam->GetBendingCoor();
  (*fTrackPar)(1,0) = trackParam->GetNonBendingCoor();
  (*fTrackPar)(2,0) = TMath::ATan(trackParam->GetBendingSlope());
  (*fTrackPar)(3,0) = TMath::ATan(TMath::Cos((*fTrackPar)(2,0))*trackParam->GetNonBendingSlope());
  (*fTrackPar)(4,0) = TMath::Cos((*fTrackPar)(3,0))*trackParam->GetInverseBendingMomentum();
  fPosition = trackParam->GetZ();
  delete trackParam;
  cout << 1/(*fTrackPar)(4,0) << " " << fPosition << " " << (*fTrackPar)(0,0) << endl;

  // Get covariance matrix
  *fCovariance = *fWeight;
  if (fCovariance->Determinant() != 0) {
      Int_t ifailCov;
      mnvertLocalK(&((*fCovariance)(0,0)), fgkSize,fgkSize,fgkSize,ifailCov);
  } else {
    AliWarning("Determinant fCovariance=0:");
  }
}

  //__________________________________________________________________________
void AliMUONTrackK::GoToZ(Double_t zEnd)
{
  // Propagates track to given Z

  ParPropagation(zEnd);
  MSThin(1); // multiple scattering in the chamber
  WeightPropagation(zEnd, kFALSE);
  fPosition = fPositionNew;
  *fTrackPar = *fTrackParNew; 
}

  //__________________________________________________________________________
void AliMUONTrackK::GoToVertex(Int_t iflag)
{
  // Version 3.08
  // Propagates track to the vertex
  // All material constants are taken from AliRoot

    static Double_t x01[5] = { 24.282,  // C
  			       24.282,  // C
  			       11.274,  // Concrete
  			        1.758,  // Fe 
  			        1.758}; // Fe (cm)
  // inner part theta < 3 degrees
    static Double_t x02[5] = { 30413,  // Air
			       24.282, // C
			       11.274, // Concrete
			       1.758,  // Fe
			       0.369}; // W (cm)
  // z positions of the materials inside the absober outer part theta > 3 degres
  static Double_t zPos[10] = {-90, -105, -315, -443, -468};

  Double_t dZ, r0Norm, x0, deltaP, dChi2, pTotal, pOld;
  AliMUONHitForRec *hit;
  AliMUONRawCluster *clus;
  TClonesArray *rawclusters;

  // First step to the rear end of the absorber
  //AZ(z->-z) Double_t zRear = 503;
  Double_t zRear = -503;
  GoToZ(zRear);
  Double_t tan3 = TMath::Tan(3./180*TMath::Pi());

  // Go through absorber
  pOld = 1/(*fTrackPar)(4,0);
  Double_t r0Rear = (*fTrackPar)(0,0)*(*fTrackPar)(0,0) + 
                    (*fTrackPar)(1,0)*(*fTrackPar)(1,0);
  r0Rear = TMath::Sqrt(r0Rear)/TMath::Abs(fPosition)/tan3;
  r0Norm = r0Rear;
  Double_t p0, cos25, cos60;
  if (!iflag) goto vertex;

  for (Int_t i=4; i>=0; i--) {
    ParPropagation(zPos[i]);
    WeightPropagation(zPos[i], kFALSE);
    dZ = TMath::Abs (fPositionNew-fPosition);
    if (r0Norm > 1) x0 = x01[i];
    else x0 = x02[i];
    MSLine(dZ,x0); // multiple scattering in the medium (linear approximation)
    fPosition = fPositionNew;
    *fTrackPar = *fTrackParNew; 
    r0Norm = (*fTrackPar)(0,0)*(*fTrackPar)(0,0) + 
             (*fTrackPar)(1,0)*(*fTrackPar)(1,0);
    r0Norm = TMath::Sqrt(r0Norm)/TMath::Abs(fPosition)/tan3;
  }
  // Correct momentum for energy losses
  pTotal = 1/TMath::Abs((*fTrackPar)(4,0));
  p0 = pTotal;
  cos25 = TMath::Cos(2.5/180*TMath::Pi());
  cos60 = TMath::Cos(6.0/180*TMath::Pi());
  for (Int_t j=0; j<1; j++) {
    /*
    if (r0Rear > 1) {
      if (p0 < 20) {
	deltaP = 2.164 + 0.145e-1*p0 - 0.417e-3*p0*p0;
      } else {
	deltaP = 2.275 + 0.102e-2*p0 - 0.674e-6*p0*p0;
      }
    } else {
      if (p0 < 20) {
	deltaP = 2.581 + 0.188e-1*p0 - 0.398e-3*p0*p0;
      } else {
	deltaP = 2.727 + 0.356e-2*p0 + 0.242e-5*p0*p0;
      }
    }
    */
    /*
    if (r0Rear < 1) {
      //W
      if (p0<15) {
	deltaP = 2.737 + 0.0494*p0 - 0.001123*p0*p0;
      } else {
	deltaP = 3.0643 + 0.01346*p0;
      }
      deltaP *= 0.95;
    } else {
      //Pb
      if (p0<15) {
	deltaP  = 2.1380 + 0.0351*p0 - 0.000853*p0*p0;
      } else {
	deltaP = 2.407 + 0.00702*p0;
      }
      deltaP *= 0.95;
    }
    */
    /*
    if (r0Rear < 1) {
      //W
      if (p0<18) {
	deltaP = 2.439 + 0.806e-1*p0 - 0.500e-2*p0*p0 + 0.106e-3*p0*p0*p0;
      } else {
	deltaP = 2.767 + 0.742e-2*p0 - 0.196e-4*p0*p0 + 0.403e-7*p0*p0*p0;
      }
      //deltaP += 0.2;
      deltaP *= cos25;
    } else {
      //Pb
      if (p0<18) {
	deltaP  = 2.209 + 0.800e-2*p0;
      } else {
	deltaP = 2.285 + 0.141e-2*p0 - 0.446e-6*p0*p0;
      }
      //deltaP += 0.2;
      deltaP *= cos60;
    }
    deltaP *= 1.1;
    */
    //*
    if (r0Rear  < 1) {
      if (p0 < 20) {
	deltaP = 2.5938 + 0.0570 * p0 - 0.001151 * p0 * p0;
      } else {
	deltaP = 3.0714 + 0.011767 * p0;
      }
    } else {
      if (p0 < 20) {
	deltaP  = 2.1207 + 0.05478 * p0 - 0.00145079 * p0 * p0;
      } else { 
	deltaP = 2.6069 + 0.0051705 * p0;
      }
    }
    deltaP *= 0.9; 
    //*/

    p0 = pTotal + deltaP/TMath::Abs(TMath::Cos((*fTrackPar)(2,0))/TMath::Cos((*fTrackPar)(3,0)));
  }
  (*fTrackPar)(4,0) = 1/p0*TMath::Sign((Double_t)1.,(*fTrackPar)(4,0));

  // Go to the vertex
vertex:
  ParPropagation((Double_t)0.);
  WeightPropagation((Double_t)0., kFALSE);
  fPosition = fPositionNew;
  //*fTrackPar = *fTrackParNew; 
  // Add vertex as a hit
  TMatrixD pointWeight(fgkSize,fgkSize);
  TMatrixD point(fgkSize,1);
  TMatrixD trackParTmp = point;
  point(0,0) = 0; // vertex coordinate - should be taken somewhere
  point(1,0) = 0; // vertex coordinate - should be taken somewhere
  pointWeight(0,0) = 1/1.e-3/1.e-3; // 10 um error
  pointWeight(1,1) = 1/1.e-3/1.e-3; // 10 um error
  TryPoint(point,pointWeight,trackParTmp,dChi2);
  *fTrackPar = trackParTmp;
  *fWeight += pointWeight; 
  fChi2 += dChi2; // Chi2
  if (fgDebug < 0) return; // no output

  cout << pOld << " " << 1/(*fTrackPar)(4,0) << " " << dChi2 << " " << fChi2 << " " << fNTrackHits << endl;
  for (Int_t i1=0; i1<fNTrackHits; i1++) {
    hit =  (AliMUONHitForRec*) ((*fTrackHitsPtr)[i1]);
    printf ("%4d", hit->GetChamberNumber()); 
  }
  cout << endl;
  if (fgDebug > 0) {
    for (Int_t i1=0; i1<fNTrackHits; i1++) {
      hit =  (AliMUONHitForRec*) ((*fTrackHitsPtr)[i1]);
      //cout << ((AliMUONHitForRec*)((*fTrackHitsPtr)[i1]))->GetHitNumber() << " ";
      //cout << ((AliMUONHitForRec*)((*fTrackHitsPtr)[i1]))->GetZ() << " ";
      printf ("%4d", fgHitForRec->IndexOf(hit)); 
    }
    cout << endl;
  }
  if (fgEventReconstructor->GetRecTrackRefHits()) { 
      // from track ref. hits
    for (Int_t i1=0; i1<fNTrackHits; i1++) {
      hit =  (AliMUONHitForRec*) ((*fTrackHitsPtr)[i1]);
      cout << hit->GetTTRTrack() + hit->GetTrackRefSignal()*10000 << " ";
    }
  } else {
    // from raw clusters
    for (Int_t i1=0; i1<fNTrackHits; i1++) {
      hit =  (AliMUONHitForRec*) ((*fTrackHitsPtr)[i1]);
      rawclusters = fgEventReconstructor->GetMUONData()->RawClusters(hit->GetChamberNumber());
      clus = (AliMUONRawCluster*) rawclusters->UncheckedAt(hit->GetHitNumber());
      printf ("%4d", clus->GetTrack(1) - 1); 
    }
    cout << endl;
    for (Int_t i1=0; i1<fNTrackHits; i1++) {
      hit =  (AliMUONHitForRec*) ((*fTrackHitsPtr)[i1]);
      rawclusters = fgEventReconstructor->GetMUONData()->RawClusters(hit->GetChamberNumber());
      clus = (AliMUONRawCluster*) rawclusters->UncheckedAt(hit->GetHitNumber());
      if (clus->GetTrack(2) != 0) printf ("%4d", clus->GetTrack(2) - 1);
      else printf ("%4s", "   ");
    }
  }
  cout << endl;
  for (Int_t i1=0; i1<fNTrackHits; i1++) {
    //cout << ((AliMUONHitForRec*)((*fTrackHitsPtr)[i1]))->GetHitNumber() << " ";
    cout << ((AliMUONHitForRec*)((*fTrackHitsPtr)[i1]))->GetZ() << " ";
    //cout << fgHitForRec->IndexOf(((AliMUONHitForRec*)((*fTrackHitsPtr)[i1]))) << " ";
  }
  cout << endl;
  for (Int_t i1=0; i1<fNTrackHits; i1++) printf("%8.4f", (*fChi2Smooth)[i1]);
  cout << endl;
  cout << "---------------------------------------------------" << endl;

  // Get covariance matrix
  /* Not needed - covariance matrix is not interesting to anybody
  *fCovariance = *fWeight;
  if (fCovariance->Determinant() != 0) {
    //   fCovariance->Invert();
    Int_t ifailCov;
    mnvertLocalK(&((*fCovariance)(0,0)), fgkSize,fgkSize,fgkSize,ifailCov);
  } else {
    AliWarning("Determinant fCovariance=0:" );
  }
  */
}

  //__________________________________________________________________________
void AliMUONTrackK::MSLine(Double_t dZ, Double_t x0)
{
  // Adds multiple scattering in a thick layer for linear propagation

  Double_t cosAlph = TMath::Cos((*fTrackPar)(2,0));
  Double_t tanAlph = TMath::Tan((*fTrackPar)(2,0));
  Double_t cosBeta = TMath::Cos((*fTrackPar)(3,0));
  Double_t sinBeta;
  sinBeta = TMath::Sin((*fTrackPar)(3,0));
  Double_t tanBeta = TMath::Tan((*fTrackPar)(3,0));
  Double_t momentum = 1/(*fTrackPar)(4,0);
  Double_t velo = 1; // relativistic velocity
  Double_t step = TMath::Abs(dZ/cosAlph/cosBeta); // step length

  // Projected scattering angle
  Double_t theta0 = 0.0136/velo/momentum/TMath::Sqrt(x0)*(1+0.038*TMath::Log(step/x0)); 
  Double_t theta02 = theta0*theta0;
  Double_t dl2 = step*step/2*theta02;
  Double_t dl3 = dl2*step*2/3;

  //Derivatives
  Double_t dYdT = 1/cosAlph;
  Double_t dYdB = 0; //(*fTrackPar)(2,0)*sinBeta/cosAlph;
  Double_t dXdT = tanAlph*tanBeta;
  //Double_t dXdB = (1+(*fTrackPar)(2,0)*tanAlph*sinBeta*sinBeta)/cosBeta;
  Double_t dXdB = 1/cosBeta;
  Double_t dAdT = 1/cosBeta;
  Double_t dAdB = 0; //(*fTrackPar)(2,0)*tanBeta;

  // Get covariance matrix
  *fCovariance = *fWeight;
  if (fCovariance->Determinant() != 0) {
    //   fCovariance->Invert();
       Int_t ifailCov;
       mnvertLocalK(&((*fCovariance)(0,0)), fgkSize,fgkSize,fgkSize,ifailCov);
  } else {
    AliWarning("Determinant fCovariance=0:" );
  }

  (*fCovariance)(0,0) += dl3*(dYdT*dYdT+dYdB*dYdB); // <yy>
  (*fCovariance)(1,1) += dl3*(dXdT*dXdT+dXdB*dXdB); // <xx>
  (*fCovariance)(2,2) += theta02*step*(dAdT*dAdT+dAdB*dAdB); // <aa>
  (*fCovariance)(3,3) += theta02*step; // <bb>

  (*fCovariance)(0,1) += dl3*(dYdT*dXdT+dYdB*dXdB); // <yx>
  (*fCovariance)(1,0) = (*fCovariance)(0,1);

  (*fCovariance)(0,2) += dl2*(dYdT*dAdT+dYdB*dAdB); // <ya>
  (*fCovariance)(2,0) = (*fCovariance)(0,2);

  (*fCovariance)(0,3) += dl2*dYdB; // <yb>
  (*fCovariance)(3,0) = (*fCovariance)(0,3);

  (*fCovariance)(1,2) += dl2*(dXdT*dAdT+dXdB*dAdB); // <xa>
  (*fCovariance)(2,1) = (*fCovariance)(1,2);

  (*fCovariance)(1,3) += dl2*dXdB; // <xb>
  (*fCovariance)(3,1) = (*fCovariance)(1,3);

  (*fCovariance)(2,3) += theta02*step*dAdB; // <ab>
  (*fCovariance)(3,2) = (*fCovariance)(2,3);

  // Get weight matrix
  *fWeight = *fCovariance;
  if (fWeight->Determinant() != 0) {
    //  fWeight->Invert();
    Int_t ifailWeight;
    mnvertLocalK(&((*fWeight)(0,0)), fgkSize,fgkSize,fgkSize,ifailWeight);
  } else {
    AliWarning("Determinant fWeight=0:");
  }
}
 
  //__________________________________________________________________________
Bool_t AliMUONTrackK::Recover(void)
{
  // Adds new failed track(s) which can be tried to be recovered
  Int_t nRecTracks;
  TClonesArray *trackPtr;
  AliMUONTrackK *trackK;

  if (fgDebug > 0) cout << " ******** Enter Recover " << endl;
  trackPtr = fgEventReconstructor->GetRecTracksPtr();

  // Remove hit with the highest chi2
  Double_t chi2 = 0;
  if (fgDebug > 0) {
    for (Int_t i=0; i<fNTrackHits; i++) {
      chi2 = fChi2Smooth ? (*fChi2Smooth)[i] : (*fChi2Array)[i];
      printf("%10.4f", chi2);
    }
    printf("\n");
    for (Int_t i=0; i<fNTrackHits; i++) {
      printf("%10d", ((AliMUONHitForRec*)fTrackHitsPtr->UncheckedAt(i))->GetChamberNumber());
    }
    printf("\n");
  }
  Double_t chi2_max = 0;
  Int_t imax = 0;
  for (Int_t i=0; i<fNTrackHits; i++) {
    chi2 = fChi2Smooth ? (*fChi2Smooth)[i] : (*fChi2Array)[i];
    if (chi2 < chi2_max) continue;
    chi2_max = chi2;
    imax = i;
  }
  //if (chi2_max < 10) return kFALSE; // !!!
  //if (chi2_max < 25) imax = fNTrackHits - 1;
  if (chi2_max < 15) imax = fNTrackHits - 1; // discard the last point
  // Check if the outlier is not from the seed segment
  AliMUONHitForRec *skipHit = (AliMUONHitForRec*) fTrackHitsPtr->UncheckedAt(imax);
  if (skipHit == fStartSegment->GetHitForRec1() || skipHit == fStartSegment->GetHitForRec2()) {
    //DropBranches(fStartSegment); // drop all tracks with the same seed segment
    return kFALSE; // to be changed probably
  }
  
  // Make a copy of track hit collection
  TObjArray *hits = new TObjArray(*fTrackHitsPtr);
  Int_t imax0;
  imax0 = imax;

  // Hits after the found one will be removed
  if (GetStation0() == 3 && skipHit->GetChamberNumber() > 7) {
    SortHits(1, fTrackHitsPtr); // unsort hits
    imax = fTrackHitsPtr->IndexOf(skipHit);
  }
  Int_t nTrackHits = fNTrackHits;
  for (Int_t i=imax+1; i<nTrackHits; i++) {
    AliMUONHitForRec *hit = (AliMUONHitForRec*) fTrackHitsPtr->UncheckedAt(i);
    fTrackHitsPtr->Remove(hit);
    hit->SetNTrackHits(hit->GetNTrackHits()-1); // unmark hit 
    fNTrackHits--;
  }

  // Check if the track candidate doesn't exist yet
  if (ExistDouble()) { delete hits; return kFALSE; }

  //DropBranches(imax0, hits); // drop branches downstream the discarded hit
  delete hits;

  nRecTracks = fgEventReconstructor->GetNRecTracks();
  skipHit = (AliMUONHitForRec*) ((*fTrackHitsPtr)[fNTrackHits-1]);
  // Remove all saved steps and smoother matrices after the skipped hit 
  RemoveMatrices(skipHit->GetZ());

  //AZ(z->-z) if (skipHit->GetZ() > fStartSegment->GetHitForRec2()->GetZ() || !fNSteps) {
  if (TMath::Abs(skipHit->GetZ()) > TMath::Abs(fStartSegment->GetHitForRec2()->GetZ()) || !fNSteps) {
    // Propagation toward high Z or skipped hit next to segment - 
    // start track from segment 
    trackK = new ((*trackPtr)[nRecTracks]) AliMUONTrackK(fStartSegment); 
    fgEventReconstructor->SetNRecTracks(nRecTracks+1);
    trackK->fRecover = 1;
    trackK->fSkipHit = skipHit;
    trackK->fNTrackHits = fNTrackHits;
    delete trackK->fTrackHitsPtr; // not efficient ?
    trackK->fTrackHitsPtr = new TObjArray(*fTrackHitsPtr);
    if (fgDebug > 0) cout << nRecTracks << " " << trackK->fRecover << endl;
    return kTRUE;
  } 

  trackK = new ((*trackPtr)[nRecTracks]) AliMUONTrackK(NULL, NULL);
  *trackK = *this;
  fgEventReconstructor->SetNRecTracks(nRecTracks+1);
  //AZ(z->-z) trackK->fTrackDir = -1;
  trackK->fTrackDir = 1;
  trackK->fRecover = 1;
  trackK->fSkipHit = skipHit;
  Int_t iD = trackK->fParFilter->Last()->GetUniqueID();
  if (iD > 1) { 
    trackK->fParFilter->Last()->SetUniqueID(iD-1);
    CreateMatrix(trackK->fParFilter); 
    iD = 1; 
    trackK->fParFilter->Last()->SetUniqueID(iD);
  }
  *((TMatrixD*)trackK->fParFilter->Last()) = *((TMatrixD*)fParExtrap->Last());
  *(trackK->fTrackPar) = *((TMatrixD*)trackK->fParFilter->Last());
  iD = trackK->fCovFilter->Last()->GetUniqueID();
  if (iD > 1) { 
    trackK->fCovFilter->Last()->SetUniqueID(iD-1);
    CreateMatrix(trackK->fCovFilter); 
    iD = 1; 
    trackK->fCovFilter->Last()->SetUniqueID(iD);
  }
  *((TMatrixD*)trackK->fCovFilter->Last()) = *((TMatrixD*)fCovExtrap->Last());
  *(trackK->fWeight) = *((TMatrixD*)trackK->fCovFilter->Last());
  if (trackK->fWeight->Determinant() != 0) {
    Int_t ifailCov;
    mnvertLocalK(&((*(trackK->fWeight))(0,0)), fgkSize,fgkSize,fgkSize,ifailCov);
  } else {
    AliWarning("Determinant fWeight=0:");
  }
  trackK->fPosition = trackK->fPositionNew = (*fSteps)[fNSteps-1];
  trackK->fChi2 = 0;
  for (Int_t i=0; i<fNTrackHits-1; i++) trackK->fChi2 += (*fChi2Array)[i];
  if (fgDebug > 0) cout << nRecTracks << " " << trackK->fRecover << endl;
  return kTRUE;
}

  //__________________________________________________________________________
void AliMUONTrackK::AddMatrices(AliMUONTrackK *trackK, Double_t dChi2, AliMUONHitForRec *hitAdd)
{
  // Adds matrices for the smoother and keep Chi2 for the point
  // Track parameters
  //trackK->fParFilter->Last()->Print();
  Int_t iD = trackK->fParFilter->Last()->GetUniqueID();
  if (iD > 1) { 
    trackK->fParFilter->Last()->SetUniqueID(iD-1);
    CreateMatrix(trackK->fParFilter); 
    iD = 1; 
  }
  *((TMatrixD*)(trackK->fParFilter->Last())) = *(trackK->fTrackPar);
  trackK->fParFilter->Last()->SetUniqueID(iD);
  if (fgDebug > 1) {
    cout << " Add matrices" << " " << fPosition << " " << dChi2 << " " << fgHitForRec->IndexOf(hitAdd) << endl;
    //trackK->fTrackPar->Print();
    //trackK->fTrackParNew->Print();
    trackK->fParFilter->Last()->Print();
    cout << " Add matrices" << endl;
  }
  // Covariance
  *(trackK->fCovariance) = *(trackK->fWeight);
  if (trackK->fCovariance->Determinant() != 0) {
    Int_t ifailCov;
    mnvertLocalK(&((*(trackK->fCovariance))(0,0)), fgkSize,fgkSize,fgkSize,ifailCov);
  } else {
    AliWarning("Determinant fCovariance=0:");
  }
  iD = trackK->fCovFilter->Last()->GetUniqueID();
  if (iD > 1) { 
    trackK->fCovFilter->Last()->SetUniqueID(iD-1);
    CreateMatrix(trackK->fCovFilter); 
    iD = 1; 
  }
  *((TMatrixD*)(trackK->fCovFilter->Last())) = *(trackK->fCovariance);
  trackK->fCovFilter->Last()->SetUniqueID(iD);

  // Save Chi2-increment for point
  Int_t indx = trackK->fTrackHitsPtr->IndexOf(hitAdd);
  if (indx < 0) indx = fNTrackHits;
  if (trackK->fChi2Array->fN <= indx) trackK->fChi2Array->Set(indx+10); 
  trackK->fChi2Array->AddAt(dChi2,indx);
}

  //__________________________________________________________________________
void AliMUONTrackK::CreateMatrix(TObjArray *objArray)
{
  // Create new matrix and add it to TObjArray 

  TMatrixD *matrix = (TMatrixD*) objArray->First();
  TMatrixD *tmp = new TMatrixD(*matrix);
  objArray->AddAt(tmp,objArray->GetLast());
  //cout << " !!! " << tmp << " " << tmp->GetUniqueID() << " " << tmp->GetNoElements() << endl;
}

  //__________________________________________________________________________
void AliMUONTrackK::RemoveMatrices(Double_t zEnd)
{
  // Remove matrices (and saved steps) in the smoother part with abs(z) < abs(zEnd)

  for (Int_t i=fNSteps-1; i>=0; i--) {
    if (fgDebug > 1) printf("%10.4f %10.4f \n", (*fSteps)[i], zEnd);
    if (TMath::Abs((*fSteps)[i]) > TMath::Abs(zEnd) - 0.01) break;
    RemoveMatrices(this);
  } // for (Int_t i=fNSteps-1;
}

  //__________________________________________________________________________
void AliMUONTrackK::RemoveMatrices(AliMUONTrackK* trackK)
{
  // Remove last saved matrices and steps in the smoother part 

  trackK->fNSteps--;
  Int_t i = trackK->fNSteps;

  Int_t id = 0;
  // Delete only matrices not shared by several tracks
  id = trackK->fParExtrap->Last()->GetUniqueID();
  if (id > 1) {
    trackK->fParExtrap->Last()->SetUniqueID(id-1);
    trackK->fParExtrap->RemoveAt(i);
  }
  else ((TMatrixD*)(trackK->fParExtrap->RemoveAt(i)))->Delete();
  id = fParFilter->Last()->GetUniqueID();
  if (id > 1) { 
    trackK->fParFilter->Last()->SetUniqueID(id-1);
    trackK->fParFilter->RemoveAt(i);
  }
  else ((TMatrixD*)(trackK->fParFilter->RemoveAt(i)))->Delete();
  id = trackK->fCovExtrap->Last()->GetUniqueID();
  if (id > 1) { 
    trackK->fCovExtrap->Last()->SetUniqueID(id-1);
    trackK->fCovExtrap->RemoveAt(i);
  }
  else ((TMatrixD*)(trackK->fCovExtrap->RemoveAt(i)))->Delete();
  id = trackK->fCovFilter->Last()->GetUniqueID();
  if (id > 1) { 
    trackK->fCovFilter->Last()->SetUniqueID(id-1);
    trackK->fCovFilter->RemoveAt(i);
  }
  else ((TMatrixD*)(trackK->fCovFilter->RemoveAt(i)))->Delete();
  id = trackK->fJacob->Last()->GetUniqueID();
  if (id > 1) { 
    trackK->fJacob->Last()->SetUniqueID(id-1);
    trackK->fJacob->RemoveAt(i);
  }
  else ((TMatrixD*)(trackK->fJacob->RemoveAt(i)))->Delete();
}

  //__________________________________________________________________________
void mnvertLocalK(Double_t *a, Int_t l, Int_t, Int_t n, Int_t &ifail)
{
//*-*-*-*-*-*-*-*-*-*-*-*Inverts a symmetric matrix*-*-*-*-*-*-*-*-*-*-*-*-*
//*-*                    ==========================
//*-*        inverts a symmetric matrix.   matrix is first scaled to
//*-*        have all ones on the diagonal (equivalent to change of units)
//*-*        but no pivoting is done since matrix is positive-definite.
//*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*

  // taken from TMinuit package of Root (l>=n)
  // fVERTs, fVERTq and fVERTpp changed to localVERTs, localVERTq and localVERTpp
  //  Double_t localVERTs[n], localVERTq[n], localVERTpp[n];
  Double_t * localVERTs = new Double_t[n];
  Double_t * localVERTq = new Double_t[n];
  Double_t * localVERTpp = new Double_t[n];
  // fMaxint changed to localMaxint
  Int_t localMaxint = n;

    /* System generated locals */
    Int_t aOffset;

    /* Local variables */
    Double_t si;
    Int_t i, j, k, kp1, km1;

    /* Parameter adjustments */
    aOffset = l + 1;
    a -= aOffset;

    /* Function Body */
    ifail = 0;
    if (n < 1) goto L100;
    if (n > localMaxint) goto L100;
//*-*-                  scale matrix by sqrt of diag elements
    for (i = 1; i <= n; ++i) {
        si = a[i + i*l];
        if (si <= 0) goto L100;
        localVERTs[i-1] = 1 / TMath::Sqrt(si);
    }
    for (i = 1; i <= n; ++i) {
        for (j = 1; j <= n; ++j) {
            a[i + j*l] = a[i + j*l]*localVERTs[i-1]*localVERTs[j-1];
        }
    }
//*-*-                                       . . . start main loop . . . .
    for (i = 1; i <= n; ++i) {
        k = i;
//*-*-                  preparation for elimination step1
        if (a[k + k*l] != 0) localVERTq[k-1] = 1 / a[k + k*l];
        else goto L100;
        localVERTpp[k-1] = 1;
        a[k + k*l] = 0;
        kp1 = k + 1;
        km1 = k - 1;
        if (km1 < 0) goto L100;
        else if (km1 == 0) goto L50;
        else               goto L40;
L40:
        for (j = 1; j <= km1; ++j) {
            localVERTpp[j-1] = a[j + k*l];
            localVERTq[j-1]  = a[j + k*l]*localVERTq[k-1];
            a[j + k*l]   = 0;
        }
L50:
        if (k - n < 0) goto L51;
        else if (k - n == 0) goto L60;
        else                goto L100;
L51:
        for (j = kp1; j <= n; ++j) {
            localVERTpp[j-1] = a[k + j*l];
            localVERTq[j-1]  = -a[k + j*l]*localVERTq[k-1];
            a[k + j*l]   = 0;
        }
//*-*-                  elimination proper
L60:
        for (j = 1; j <= n; ++j) {
            for (k = j; k <= n; ++k) { a[j + k*l] += localVERTpp[j-1]*localVERTq[k-1]; }
        }
    }
//*-*-                  elements of left diagonal and unscaling
    for (j = 1; j <= n; ++j) {
        for (k = 1; k <= j; ++k) {
            a[k + j*l] = a[k + j*l]*localVERTs[k-1]*localVERTs[j-1];
            a[j + k*l] = a[k + j*l];
        }
    }
    delete [] localVERTs;
    delete [] localVERTq;
    delete [] localVERTpp;
    return;
//*-*-                  failure return
L100:
    delete [] localVERTs;
    delete [] localVERTq;
    delete [] localVERTpp;
    ifail = 1;
} /* mnvertLocal */

  //__________________________________________________________________________
Bool_t AliMUONTrackK::Smooth(void)
{
  // Apply smoother
  Int_t ihit = fNTrackHits - 1;
  AliMUONHitForRec *hit = (AliMUONHitForRec*) (*fTrackHitsPtr)[ihit];
  fChi2Smooth = new TArrayD(fNTrackHits);
  fChi2Smooth->Reset(-1);
  fChi2 = 0;
  fParSmooth = new TObjArray(15);
  fParSmooth->Clear();

  if (fgDebug > 0) {
    cout << " ******** Enter Smooth " << endl;
    cout << (*fSteps)[fNSteps-1] << " " << fPosition << " " << fPositionNew << endl; 
    /*
    for (Int_t i=fNSteps-1; i>=0; i--) cout << (*fSteps)[i] << " ";
    cout << endl;
    for (Int_t i=fNSteps-1; i>=0; i--) {cout << i; ((TMatrixD*)fParFilter->UncheckedAt(i))->Print(); }
    */
    for (Int_t i=ihit; i>=0; i--) cout << ((AliMUONHitForRec*)(*fTrackHitsPtr)[i])->GetZ() << " ";
    cout << endl;
  }

  // Find last point corresponding to the last hit
  Int_t iLast = fNSteps - 1;
  for ( ; iLast>=0; iLast--) {
    //AZ(z->-z) if ((*fSteps)[iLast] + 0.01 > ((AliMUONHitForRec*)(*fTrackHitsPtr)[fNTrackHits-1])->GetZ()) break;
    if (TMath::Abs((*fSteps)[iLast]) + 0.01 > TMath::Abs(((AliMUONHitForRec*)(*fTrackHitsPtr)[fNTrackHits-1])->GetZ())) break;
  }

  TMatrixD parSmooth = *((TMatrixD*)(fParFilter->UncheckedAt(iLast))); // last filtered = first smoothed
  //parSmooth.Dump();
  TMatrixD covSmooth = *((TMatrixD*)(fCovFilter->UncheckedAt(iLast))); // last filtered = first smoothed
  TMatrixD tmp=covSmooth, weight=covSmooth, gain = covSmooth;
  TMatrixD tmpPar = *fTrackPar;
  //parSmooth.Print(); ((TMatrixD*)(fParExtrap->Last()))->Print(); 

  Bool_t found;
  Double_t chi2_max = 0;
  for (Int_t i=iLast+1; i>0; i--) {
    if (i == iLast + 1) goto L33; // temporary fix

    // Smoother gain matrix
    weight = *((TMatrixD*)(fCovExtrap->UncheckedAt(i)));
    if (weight.Determinant() != 0) {
      Int_t ifailCov;
      mnvertLocalK(&(weight(0,0)), fgkSize,fgkSize,fgkSize,ifailCov);
    } else {
      AliWarning("Determinant weight=0:");
    }
    // Fk'Wkk+1
    tmp = TMatrixD(*((TMatrixD*)(fJacob->UncheckedAt(i))),TMatrixD::kTransposeMult,weight);
    gain = TMatrixD(*((TMatrixD*)(fCovFilter->UncheckedAt(i-1))),TMatrixD::kMult,tmp);
    //cout << (*fSteps)[i-1] << " " << (*fSteps)[i] << endl; gain.Print();

    // Smoothed parameter vector
    //((TMatrixD*)(fParExtrap->UncheckedAt(i)))->Dump();
    parSmooth -= *((TMatrixD*)(fParExtrap->UncheckedAt(i)));
    tmpPar = *((TMatrixD*)(fParFilter->UncheckedAt(i-1)));
    tmpPar += TMatrixD(gain,TMatrixD::kMult,parSmooth);
    parSmooth = tmpPar;

    // Smoothed covariance
    covSmooth -= *((TMatrixD*)(fCovExtrap->UncheckedAt(i)));
    weight = TMatrixD(TMatrixD::kTransposed,gain);
    tmp = TMatrixD(covSmooth,TMatrixD::kMult,weight);
    covSmooth = *((TMatrixD*)(fCovFilter->UncheckedAt(i-1)));
    covSmooth += TMatrixD(gain,TMatrixD::kMult,tmp);

    // Check if there was a measurement at given z
    found = kFALSE;
    for ( ; ihit>=0; ihit--) { 
      hit = (AliMUONHitForRec*) (*fTrackHitsPtr)[ihit];
      if (TMath::Abs(hit->GetZ()-(*fSteps)[i-1]) < 0.1) { found = kTRUE; break; }
      //AZ(z->-z) else if (ihit < fNTrackHits-1 && hit->GetZ() > (*fSteps)[i-1]) { ihit++; break; }
      else if (ihit < fNTrackHits-1 && TMath::Abs(hit->GetZ()) > TMath::Abs((*fSteps)[i-1])) { ihit++; break; }
    }
    if (!found) continue; // no measurement - skip the rest
    else if (fgDebug > 1) cout << i << " " << ihit << " " << hit->GetZ() << endl;
    if (ihit == 0) continue; // the first hit - skip the rest

L33:
    // Smoothed residuals
    tmpPar = 0;
    tmpPar(0,0) = hit->GetBendingCoor() - parSmooth(0,0); // bending coordinate
    tmpPar(1,0) = hit->GetNonBendingCoor() - parSmooth(1,0); // non-bending coordinate
    if (fgDebug > 1) {
      cout << hit->GetBendingCoor() << " " << parSmooth(0,0) << " " << tmpPar(0,0) << endl;
      cout << hit->GetNonBendingCoor() << " " << parSmooth(1,0) << " " << tmpPar(1,0) << endl;
    }
    // Cov. matrix of smoothed residuals
    tmp = 0;
    tmp(0,0) = hit->GetBendingReso2() - covSmooth(0,0);
    tmp(1,1) = hit->GetNonBendingReso2() - covSmooth(1,1);
    tmp(0,1) = tmp(1,0) = -covSmooth(0,1);
    tmp(2,2) = tmp(3,3) = tmp(4,4) = 1;

    // Calculate Chi2 of smoothed residuals
    if (tmp.Determinant() != 0) {
      Int_t ifailCov;
      mnvertLocalK(&(tmp(0,0)), fgkSize,fgkSize,fgkSize,ifailCov);
    } else {
      AliWarning("Determinant tmp=0:");
    }
    TMatrixD vector(tmp,TMatrixD::kMult,tmpPar);
    TMatrixD chi2(tmpPar,TMatrixD::kTransposeMult,vector);
    if (fgDebug > 1) chi2.Print();
    (*fChi2Smooth)[ihit] = chi2(0,0);
    if (chi2(0,0) > chi2_max) chi2_max = chi2(0,0); 
    fChi2 += chi2(0,0);
    if (chi2(0,0) < 0) { 
      chi2.Print(); cout << i << " " << iLast << endl;
      AliFatal("chi2 < 0.");
    }
    // Save smoothed parameters
    TMatrixD *par = new TMatrixD(parSmooth);
    fParSmooth->AddAt(par, ihit);

  } // for (Int_t i=iLast+1;

  //if (chi2_max > 16) { 
  //if (chi2_max > 25) { 
  //if (chi2_max > 50) { 
  //if (chi2_max > 100) { 
  if (chi2_max > fgkChi2max) { 
    //if (Recover()) DropBranches(); 
    //Recover();
    Outlier();
    return kFALSE; 
  }
  return kTRUE;
}
 
  //__________________________________________________________________________
void AliMUONTrackK::Outlier()
{
  // Adds new track with removed hit having the highest chi2

  if (fgDebug > 0) {
    cout << " ******** Enter Outlier " << endl;
    for (Int_t i=0; i<fNTrackHits; i++) printf("%10.4f", (*fChi2Smooth)[i]);
    printf("\n");
    for (Int_t i=0; i<fNTrackHits; i++) {
      printf("%10d", ((AliMUONHitForRec*)fTrackHitsPtr->UncheckedAt(i))->GetChamberNumber());
    }
    printf("\n");
  }

  Double_t chi2_max = 0;
  Int_t imax = 0;
  for (Int_t i=0; i<fNTrackHits; i++) {
    if ((*fChi2Smooth)[i] < chi2_max) continue;
    chi2_max = (*fChi2Smooth)[i];
    imax = i;
  }
  // Check if the outlier is not from the seed segment
  AliMUONHitForRec *hit = (AliMUONHitForRec*) fTrackHitsPtr->UncheckedAt(imax);
  if (hit == fStartSegment->GetHitForRec1() || hit == fStartSegment->GetHitForRec2()) return; // to be changed probably

  // Check for missing station
  Int_t ok = 1;
  if (imax == 0) {
    if (((AliMUONHitForRec*)fTrackHitsPtr->UncheckedAt(1))->GetChamberNumber() < 8) ok--; 
  } else if (imax == fNTrackHits-1) {
    if (((AliMUONHitForRec*)fTrackHitsPtr->UncheckedAt(fNTrackHits-2))->GetChamberNumber() > 1) ok--; 
  } 
  else if (((AliMUONHitForRec*)fTrackHitsPtr->UncheckedAt(imax-1))->GetChamberNumber()/2 - ((AliMUONHitForRec*)fTrackHitsPtr->UncheckedAt(imax+1))->GetChamberNumber()/2 > 1) ok--;
  if (!ok) { Recover(); return; } // try to recover track
  //AZ if (!ok) { if (fgDebug >= 0) cout << imax << endl; DropBranches(imax, 0); return; } 

  // Remove saved steps and smoother matrices after the outlier
  RemoveMatrices(hit->GetZ()); 
  
  // Check for possible double track candidates
  //if (ExistDouble(hit)) return;

  TClonesArray *trackPtr = fgEventReconstructor->GetRecTracksPtr();
  Int_t nRecTracks = fgEventReconstructor->GetNRecTracks();

  AliMUONTrackK *trackK = 0;
  if (!fNSteps || GetStation0() == 3 && hit->GetChamberNumber() > 7) {
    // start track from segment 
    trackK = new ((*trackPtr)[nRecTracks]) AliMUONTrackK(fStartSegment); 
    fgEventReconstructor->SetNRecTracks(nRecTracks+1);
    trackK->fRecover = 2;
    trackK->fSkipHit = hit;
    trackK->fNTrackHits = fNTrackHits;
    delete trackK->fTrackHitsPtr; // not efficient ?
    trackK->fTrackHitsPtr = new TObjArray(*fTrackHitsPtr);
    if (GetStation0() == 3) trackK->SortHits(1, trackK->fTrackHitsPtr);
    if (fgDebug > 0) cout << nRecTracks << " Outlier" << endl;
    return;
  } 
  trackK = new ((*trackPtr)[nRecTracks]) AliMUONTrackK(NULL, NULL);
  *trackK = *this;
  fgEventReconstructor->SetNRecTracks(nRecTracks+1);
  //AZ(z->-z) trackK->fTrackDir = -1;
  trackK->fTrackDir = 1;
  trackK->fRecover = 2;
  trackK->fSkipHit = hit;
  Int_t iD = trackK->fParFilter->Last()->GetUniqueID();
  if (iD > 1) { 
    trackK->fParFilter->Last()->SetUniqueID(iD-1);
    CreateMatrix(trackK->fParFilter); 
    iD = 1; 
    trackK->fParFilter->Last()->SetUniqueID(iD);
  }
  *((TMatrixD*)trackK->fParFilter->Last()) = *((TMatrixD*)fParExtrap->Last());
  *(trackK->fTrackPar) = *((TMatrixD*)trackK->fParFilter->Last());
  iD = trackK->fCovFilter->Last()->GetUniqueID();
  if (iD > 1) { 
    trackK->fCovFilter->Last()->SetUniqueID(iD-1);
    CreateMatrix(trackK->fCovFilter); 
    iD = 1; 
    trackK->fCovFilter->Last()->SetUniqueID(iD);
  }
  *((TMatrixD*)trackK->fCovFilter->Last()) = *((TMatrixD*)fCovExtrap->Last());
  *(trackK->fWeight) = *((TMatrixD*)trackK->fCovFilter->Last());
  if (trackK->fWeight->Determinant() != 0) {
    Int_t ifailCov;
    mnvertLocalK(&((*(trackK->fWeight))(0,0)), fgkSize,fgkSize,fgkSize,ifailCov);
  } else {
    AliWarning("Determinant fWeight=0:");
  }
  trackK->fPosition = trackK->fPositionNew = (*fSteps)[fNSteps-1];
  trackK->fChi2 = 0;
  for (Int_t i=0; i<fNTrackHits-1; i++) trackK->fChi2 += (*fChi2Array)[i];
  if (fgDebug > 0) cout << nRecTracks << " Outlier " << trackK->fChi2 << endl;
}

  //__________________________________________________________________________
Double_t AliMUONTrackK::GetChi2PerPoint(Int_t iPoint) const
{
  // Return Chi2 at point
  return fChi2Smooth ? (*fChi2Smooth)[iPoint] : (*fChi2Array)[iPoint];
  //return 0.;
}

  //__________________________________________________________________________
void AliMUONTrackK::Print(FILE *lun) const
{
  // Print out track information

  Int_t flag = 1;
  AliMUONHitForRec *hit = 0; 
  if (fgEventReconstructor->GetRecTrackRefHits()) { 
    // from track ref. hits
    for (Int_t j=0; j<fNTrackHits; j++) {
      hit = (AliMUONHitForRec*) fTrackHitsPtr->UncheckedAt(j);
      if (hit->GetTTRTrack() > 1) { flag = 0; break; }
    }
    for (Int_t j=0; j<fNTrackHits; j++) {
      printf("%10.4f", GetChi2PerPoint(j));
      if (GetChi2PerPoint(j) > -0.1) {
	hit = (AliMUONHitForRec*) fTrackHitsPtr->UncheckedAt(j);
	fprintf(lun,"%3d %3d %10.4f", gAlice->GetEvNumber(), hit->GetChamberNumber(), GetChi2PerPoint(j));
	fprintf(lun, "%3d %3d %3d \n", hit->GetTrackRefSignal(), hit->GetTTRTrack(), flag);
      }
    }
    printf("\n");
  } else {
    // from raw clusters
    AliMUONRawCluster *clus = 0;
    TClonesArray *rawclusters = 0;
    for (Int_t i1=0; i1<fNTrackHits; i1++) {
      hit =  (AliMUONHitForRec*) ((*fTrackHitsPtr)[i1]);
      rawclusters = fgEventReconstructor->GetMUONData()->RawClusters(hit->GetChamberNumber());
      clus = (AliMUONRawCluster*) rawclusters->UncheckedAt(hit->GetHitNumber());
      if (TMath::Abs(clus->GetTrack(1)-1) < 2) {
	if (clus->GetTrack(2)) flag = 2;
	continue;
      }
      if (clus->GetTrack(2) && TMath::Abs(clus->GetTrack(2)-1) < 2) {
	flag = 3;
	continue;
      }
      flag = 0;
      break;
    }
    Int_t sig[2]={1,1}, tid[2]={0};
    for (Int_t i1=0; i1<fNTrackHits; i1++) {
      if (GetChi2PerPoint(i1) < -0.1) continue;
      hit =  (AliMUONHitForRec*) ((*fTrackHitsPtr)[i1]);
      rawclusters = fgEventReconstructor->GetMUONData()->RawClusters(hit->GetChamberNumber());
      clus = (AliMUONRawCluster*) rawclusters->UncheckedAt(hit->GetHitNumber());
      for (Int_t j=0; j<2; j++) {
	tid[j] = clus->GetTrack(j+1) - 1;
	if (clus->GetTrack(j+1) < 0) { sig[j] = 0; tid[j] = 999; }
      }
      fprintf(lun,"%3d %3d %10.4f", gAlice->GetEvNumber(), hit->GetChamberNumber(), GetChi2PerPoint(i1));
      if (!(clus->GetTrack(2))) fprintf(lun, "%3d %3d", sig[0], tid[0]); // simple cluster
      else { // track overlap
	fprintf(lun, "%3d %3d", TMath::Max(sig[0],sig[1]), TMath::Min(tid[0],tid[1]));
	//if (tid[0] < 2) flag *= 2;
	//else if (tid[1] < 2) flag *= 3;
      }
      fprintf (lun, "%3d \n", flag); 
    }
  }
}

  //__________________________________________________________________________
void AliMUONTrackK::DropBranches(Int_t imax, TObjArray *hits)
{
  // Drop branches downstream of the skipped hit 
  Int_t nRecTracks;
  TClonesArray *trackPtr;
  AliMUONTrackK *trackK;

  trackPtr = fgEventReconstructor->GetRecTracksPtr();
  nRecTracks = fgEventReconstructor->GetNRecTracks();
  Int_t icand = trackPtr->IndexOf(this);
  if (!hits) hits = fTrackHitsPtr; 

  // Check if the track candidate doesn't exist yet
  for (Int_t i=icand+1; i<nRecTracks; i++) {
    trackK = (AliMUONTrackK*) ((*trackPtr)[i]);
    if (trackK->fNTrackHits == 2 && trackK->GetRecover() == 0) continue;
    if (trackK->GetRecover() < 0) continue;

    if (trackK->fNTrackHits >= imax + 1) {
      for (Int_t j=0; j<=imax; j++) {
	//if (j != fNTrackHits-1 && (*trackK->fTrackHitsPtr)[j] != (*fTrackHitsPtr)[j]) break;
	if ((*trackK->fTrackHitsPtr)[j] != (*hits)[j]) break;
	if (j == imax) {
	  if (hits != fTrackHitsPtr) {
	    // Drop all branches downstream the hit (for Recover)
	    trackK->SetRecover(-1);
	    if (fgDebug >= 0 )cout << " Recover " << i << endl;
	    continue;
	  }
	  // Check if the removal of the hit breaks the track
	  Int_t ok = 1;
	  if (imax == 0) {
	    if (((AliMUONHitForRec*)trackK->fTrackHitsPtr->UncheckedAt(1))->GetChamberNumber() < 8) ok--; }
	  else if (imax == trackK->fNTrackHits-1) continue;
	    // else if (imax == trackK->fNTrackHits-1) {
	    //if (((AliMUONHitForRec*)trackK->fTrackHitsPtr->UncheckedAt(trackK->fNTrackHits-2))->GetChamberNumber() > 1) ok--; 
	    //} 
	  else if (((AliMUONHitForRec*)trackK->fTrackHitsPtr->UncheckedAt(imax-1))->GetChamberNumber()/2 - ((AliMUONHitForRec*)trackK->fTrackHitsPtr->UncheckedAt(imax+1))->GetChamberNumber()/2 > 1) ok--;
	  if (!ok) trackK->SetRecover(-1);
	}
      } // for (Int_t j=0;
    }
  } // for (Int_t i=0;
}

  //__________________________________________________________________________
void AliMUONTrackK::DropBranches(AliMUONSegment *segment)
{
  // Drop all candidates with the same seed segment
  Int_t nRecTracks;
  TClonesArray *trackPtr;
  AliMUONTrackK *trackK;

  trackPtr = fgEventReconstructor->GetRecTracksPtr();
  nRecTracks = fgEventReconstructor->GetNRecTracks();
  Int_t icand = trackPtr->IndexOf(this);

  for (Int_t i=icand+1; i<nRecTracks; i++) {
    trackK = (AliMUONTrackK*) ((*trackPtr)[i]);
    if (trackK->fNTrackHits == 2 && trackK->GetRecover() == 0) continue;
    if (trackK->GetRecover() < 0) continue;
    if (trackK->fStartSegment == segment) trackK->SetRecover(-1);
  }
  if (fgDebug >= 0) cout << " Drop segment " << endl; 
}

  //__________________________________________________________________________
AliMUONHitForRec* AliMUONTrackK::GetHitLastOk(void)
{
  // Return the hit where track stopped

  if (!fNSteps) return (AliMUONHitForRec*)((*fTrackHitsPtr)[1]);
  return fSkipHit;
}

  //__________________________________________________________________________
Int_t AliMUONTrackK::GetStation0(void)
{
  // Return seed station number
  return fStartSegment->GetHitForRec1()->GetChamberNumber() / 2;
}

  //__________________________________________________________________________
Bool_t AliMUONTrackK::ExistDouble(AliMUONHitForRec *hit)
{
  // Check if the track will make a double after outlier removal

  TClonesArray *trackPtr = fgEventReconstructor->GetRecTracksPtr();
  Int_t nRecTracks = fgEventReconstructor->GetNRecTracks();
  TObjArray *hitArray = new TObjArray(*fTrackHitsPtr);
  TObjArray *hitArray1 = new TObjArray(*hitArray);
  hitArray1->Remove(hit);
  hitArray1->Compress();

  Bool_t same = kFALSE;
  for (Int_t i=0; i<nRecTracks; i++) {
    AliMUONTrackK *trackK = (AliMUONTrackK*) ((*trackPtr)[i]);
    if (trackK->fNTrackHits == 2 && trackK->GetRecover() == 0) continue;
    if (trackK == this) continue;
    if (trackK->fNTrackHits == fNTrackHits || trackK->fNTrackHits == fNTrackHits-1) {
      TObjArray *hits = new TObjArray(*trackK->fTrackHitsPtr);
      same = kTRUE;
      if (trackK->fNTrackHits == fNTrackHits) {
	for (Int_t j=0; j<fNTrackHits; j++) {
	  if (hits->UncheckedAt(j) != hitArray->UncheckedAt(j)) { same = kFALSE; break; }
	}
	if (same) { delete hits; break; }
	if (trackK->fSkipHit) {
	  TObjArray *hits1 = new TObjArray(*hits);
	  if (hits1->Remove(trackK->fSkipHit) > 0) {
	    hits1->Compress();
	    same = kTRUE;
	    for (Int_t j=0; j<fNTrackHits-1; j++) {
	      if (hits1->UncheckedAt(j) != hitArray1->UncheckedAt(j)) { same = kFALSE; break; }
	    }
	    if (same) { delete hits1; break; }
	  }
	  delete hits1;
	}
      } else {
	// Check with removed outlier
	same = kTRUE;
	for (Int_t j=0; j<fNTrackHits-1; j++) {
	  if (hits->UncheckedAt(j) != hitArray1->UncheckedAt(j)) { same = kFALSE; break; }
	}
	if (same) { delete hits; break; }
      } 
      delete hits;
    }
  } // for (Int_t i=0; i<nRecTracks;
  delete hitArray; delete hitArray1;
  if (same && fgDebug >= 0) cout << " Same" << endl;
  return same;
}

  //__________________________________________________________________________
Bool_t AliMUONTrackK::ExistDouble(void)
{
  // Check if the track will make a double after recovery

  TClonesArray *trackPtr = fgEventReconstructor->GetRecTracksPtr();
  Int_t nRecTracks = fgEventReconstructor->GetNRecTracks();

  TObjArray *hitArray = new TObjArray(*fTrackHitsPtr);
  if (GetStation0() == 3) SortHits(0, hitArray); // sort
  //if (GetStation0() == 3) SortHits(1, hitArray); // unsort

  Bool_t same = kFALSE;
  for (Int_t i=0; i<nRecTracks; i++) {
    AliMUONTrackK *trackK = (AliMUONTrackK*) ((*trackPtr)[i]);
    if (trackK->fNTrackHits == 2 && trackK->GetRecover() == 0) continue;
    if (trackK == this) continue;
    //AZ if (trackK->GetRecover() < 0) continue; //
    if (trackK->fNTrackHits >= fNTrackHits) {
      TObjArray *hits = new TObjArray(*trackK->fTrackHitsPtr);
      if (trackK->GetStation0() == 3) SortHits(0, hits); // sort
      //if (trackK->GetStation0() == 3) SortHits(1, hits); // unsort
      for (Int_t j=0; j<fNTrackHits; j++) {
	//cout << fNTrackHits << " " << i << " " << j << " " << (*hitArray)[j] << " " << (*hits)[j] << " " << trackK->fSkipHit << endl;
	if (j != fNTrackHits-1 && (*hitArray)[j] != (*hits)[j]) break; 
	if (j == fNTrackHits-1) {
	  if (trackK->fSkipHit && TMath::Abs(((AliMUONHitForRec*)((*hitArray)[j]))->GetZ()-trackK->fSkipHit->GetZ()) < 0.5) same = kTRUE; 
	  //if (trackK->fNTrackHits > fNTrackHits && 
	  //if (trackK->fSkipHit) cout << ((AliMUONHitForRec*)((*hitArray)[j]))->GetZ() << " " << trackK->fSkipHit->GetZ() << endl;
	}
      } // for (Int_t j=0;
      delete hits;
      if (same) break; 
    }
  } // for (Int_t i=0;
  delete hitArray;
  return same;
}