[u/mrichter/AliRoot.git] / STEER / AliVertexerTracks.cxx

/**************************************************************************
 * Copyright(c) 1998-2003, 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.                  *
 **************************************************************************/

//-----------------------------------------------------------------
//    Implementation of the vertexer from ESD tracks
//
// Origin: AliITSVertexerTracks
//         A.Dainese, Padova, 
//         andrea.dainese@pd.infn.it
//         M.Masera,  Torino, 
//         massimo.masera@to.infn.it
// Moved to STEER and adapted to ESD tracks: 
//          F.Prino,  Torino, prino@to.infn.it
//-----------------------------------------------------------------

//---- Root headers --------
#include <TTree.h>
//---- AliRoot headers -----
#include "AliStrLine.h"
#include "AliVertexerTracks.h"
#include "AliESD.h"
#include "AliESDtrack.h"

ClassImp(AliVertexerTracks)


//----------------------------------------------------------------------------
AliVertexerTracks::AliVertexerTracks():
 TObject(),fVert() 
{
//
// Default constructor
//
  SetVtxStart();
  SetMinTracks();
  fDCAcut=0;
  fAlgo=1;
}
//-----------------------------------------------------------------------------
AliVertexerTracks::AliVertexerTracks(Double_t xStart, Double_t yStart):
 TObject(),fVert() 
{
//
// Standard constructor
//
  SetVtxStart(xStart,yStart);
  SetMinTracks();
  fDCAcut=0;
  fAlgo=1;
}
//-----------------------------------------------------------------------------
AliVertexerTracks::~AliVertexerTracks() {
  // Default Destructor
  // The objects poited by the following pointers are not owned
  // by this class and are not deleted
}
//----------------------------------------------------------------------------
Int_t AliVertexerTracks::PrepareTracks(TTree &trkTree) {
//
// Propagate tracks to initial vertex position and store them in a TObjArray
//
  Double_t alpha,xlStart;
  Int_t    nTrks    = 0;

  Int_t    nEntries = (Int_t)trkTree.GetEntries();
  if(!fTrkArray.IsEmpty()) fTrkArray.Clear();
  fTrkArray.Expand(nEntries);

  for(Int_t i=0; i<nEntries; i++) {
    AliESDtrack *track = new AliESDtrack; 
    trkTree.SetBranchAddress("tracks",&track);
    trkTree.GetEvent(i);

    // propagate track to vtxSeed
    alpha  = track->GetAlpha();
    xlStart = fNominalPos[0]*TMath::Cos(alpha)+fNominalPos[1]*TMath::Sin(alpha);
    track->PropagateTo(xlStart,GetField());   // to vtxSeed
    fTrkArray.AddLast(track);
    nTrks++; 
  }
  return nTrks;
} 
//----------------------------------------------------------------------------
AliVertex* AliVertexerTracks::VertexForSelectedTracks(TTree *trkTree) {
//
// Return vertex from tracks in trkTree
//

  // get tracks and propagate them to initial vertex position
  Int_t nTrks = PrepareTracks(*trkTree);
  if(nTrks < fMinTracks) {
    printf("TooFewTracks\n");
    Double_t vtx[3]={0,0,0};
    fVert.SetXYZ(vtx);
    fVert.SetDispersion(999);
    fVert.SetNContributors(-5);
    return &fVert;
  }
 
  // Set initial vertex position from ESD
  if(fAlgo==1)  StrLinVertexFinderMinDist(1);
  if(fAlgo==2)  StrLinVertexFinderMinDist(0);
  if(fAlgo==3)  HelixVertexFinder();
  if(fAlgo==4)  VertexFinder(1);
  if(fAlgo==5)  VertexFinder(0);
  return &fVert;
}

//----------------------------------------------------------------------------
AliESDVertex* AliVertexerTracks::FindVertex(const AliESD *event) {
//
// This is a simple wrapping (by Jouri.Belikov@cern.ch) over the original
// code by the authors of this class.
//
  Int_t nt=event->GetNumberOfTracks(), nacc=0;
  while (nt--) {
    AliESDtrack *t=event->GetTrack(nt);
    if ((t->GetStatus()&AliESDtrack::kITSrefit)==0) continue;
    fTrkArray.AddLast(t);
    nacc++;
  }

  // get tracks and propagate them to initial vertex position
  if(nacc < fMinTracks) {
    printf("TooFewTracks\n");
    Double_t vtx[3]={0,0,0};
    fVert.SetXYZ(vtx);
    fVert.SetDispersion(999);
    fVert.SetNContributors(-5);
  } else 
    switch (fAlgo) {
       case 1: StrLinVertexFinderMinDist(1); break;
       case 2: StrLinVertexFinderMinDist(0); break;
       case 3: HelixVertexFinder();          break;
       case 4: VertexFinder(1);              break;
       case 5: VertexFinder(0);              break;
       default: printf("Wrong algorithm\n"); break;  
    }

  fTrkArray.Clear();
  return &fVert;
}


//----------------------------------------------------------------------------
AliVertex* AliVertexerTracks::VertexForSelectedTracks(TObjArray *trkArray) {
//
// Return vertex from array of tracks
//

  // get tracks and propagate them to initial vertex position
  Int_t nTrks = trkArray->GetEntriesFast();
  if(nTrks < fMinTracks) {
    printf("TooFewTracks\n");
    Double_t vtx[3]={0,0,0};
    fVert.SetXYZ(vtx);
    fVert.SetDispersion(999);
    fVert.SetNContributors(-5);
    return &fVert;
  }
  TTree *trkTree = new TTree("TreeT","tracks");
  AliESDtrack *esdTrack = 0;
  trkTree->Branch("tracks","AliESDtrack",&esdTrack);
  for(Int_t i=0; i<nTrks; i++){
    esdTrack = (AliESDtrack*)trkArray->At(i);
    trkTree->Fill();
  }
    
  AliVertex *vtx =  VertexForSelectedTracks(trkTree);
  delete trkTree;
  return vtx;
}

//---------------------------------------------------------------------------
void AliVertexerTracks::VertexFinder(Int_t optUseWeights) {

  // Get estimate of vertex position in (x,y) from tracks DCA
 
  Double_t initPos[3];
  initPos[2] = 0.;
  for(Int_t i=0;i<2;i++)initPos[i]=fNominalPos[i];
  Int_t nacc = (Int_t)fTrkArray.GetEntriesFast();
  Double_t aver[3]={0.,0.,0.};
  Double_t aversq[3]={0.,0.,0.};
  Double_t sigmasq[3]={0.,0.,0.};
  Double_t sigma=0;
  Int_t ncombi = 0;
  AliESDtrack *track1;
  AliESDtrack *track2;
  Double_t alpha,mindist;
  Double_t field=GetField();

  for(Int_t i=0; i<nacc; i++){
    track1 = (AliESDtrack*)fTrkArray.At(i);
    alpha=track1->GetAlpha();
    mindist = TMath::Cos(alpha)*fNominalPos[0]+TMath::Sin(alpha)*fNominalPos[1];

    Double_t pos[3]; track1->GetXYZAt(mindist,field,pos);
    Double_t dir[3]; track1->GetPxPyPzAt(mindist,field,dir);
    AliStrLine *line1 = new AliStrLine(pos,dir);
   
    for(Int_t j=i+1; j<nacc; j++){
      track2 = (AliESDtrack*)fTrkArray.At(j);
      alpha=track2->GetAlpha();
      mindist = TMath::Cos(alpha)*fNominalPos[0]+TMath::Sin(alpha)*fNominalPos[1];

      Double_t pos[3]; track2->GetXYZAt(mindist,field,pos);
      Double_t dir[3]; track2->GetPxPyPzAt(mindist,field,dir);
      AliStrLine *line2 = new AliStrLine(pos,dir);

      Double_t distCA=line2->GetDCA(line1);
      if(fDCAcut<=0 || (fDCAcut>0&&distCA<fDCAcut)){
	Double_t pnt1[3],pnt2[3],crosspoint[3];

	if(optUseWeights<=0){
	  Int_t retcode = line2->Cross(line1,crosspoint);
	  if(retcode>=0){
	    ncombi++;
	    for(Int_t jj=0;jj<3;jj++)aver[jj]+=crosspoint[jj];
	    for(Int_t jj=0;jj<3;jj++)aversq[jj]+=(crosspoint[jj]*crosspoint[jj]);
	  }
	}
	if(optUseWeights>0){
	  Int_t retcode = line1->CrossPoints(line2,pnt1,pnt2);
	  if(retcode>=0){
	    Double_t alpha, cs, sn;
	    alpha=track1->GetAlpha();
	    cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);	  
	    Double_t sx1=sn*sn*track1->GetSigmaY2(), sy1=cs*cs*track1->GetSigmaY2();
	    alpha=track2->GetAlpha();
	    cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
	    Double_t sx2=sn*sn*track2->GetSigmaY2(), sy2=cs*cs*track2->GetSigmaY2();
	    Double_t sz1=track1->GetSigmaZ2(), sz2=track2->GetSigmaZ2();
	    Double_t wx1=sx2/(sx1+sx2), wx2=1.- wx1;
	    Double_t wy1=sy2/(sy1+sy2), wy2=1.- wy1;
	    Double_t wz1=sz2/(sz1+sz2), wz2=1.- wz1;
	    crosspoint[0]=wx1*pnt1[0] + wx2*pnt2[0]; 
	    crosspoint[1]=wy1*pnt1[1] + wy2*pnt2[1]; 
	    crosspoint[2]=wz1*pnt1[2] + wz2*pnt2[2];
	  
	    ncombi++;
	    for(Int_t jj=0;jj<3;jj++)aver[jj]+=crosspoint[jj];
	    for(Int_t jj=0;jj<3;jj++)aversq[jj]+=(crosspoint[jj]*crosspoint[jj]);
	  }
	}
      }
      delete line2;
    }
    delete line1;
  }
  if(ncombi>0){
    for(Int_t jj=0;jj<3;jj++){
      initPos[jj] = aver[jj]/ncombi;
      aversq[jj]/=ncombi;
      sigmasq[jj]=aversq[jj]-initPos[jj]*initPos[jj];
      sigma+=sigmasq[jj];
    }
    sigma=TMath::Sqrt(TMath::Abs(sigma));
  }
  else {
    Warning("VertexFinder","Finder did not succed");
    sigma=999;
  }
  fVert.SetXYZ(initPos);
  fVert.SetDispersion(sigma);
  fVert.SetNContributors(ncombi);
}
//---------------------------------------------------------------------------
void AliVertexerTracks::HelixVertexFinder() {

  // Get estimate of vertex position in (x,y) from tracks DCA


  Double_t initPos[3];
  initPos[2] = 0.;
  for(Int_t i=0;i<2;i++)initPos[i]=fNominalPos[i];
  Double_t field=GetField();

  Int_t nacc = (Int_t)fTrkArray.GetEntriesFast();

  Double_t aver[3]={0.,0.,0.};
  Double_t averquad[3]={0.,0.,0.};
  Double_t sigmaquad[3]={0.,0.,0.};
  Double_t sigma=0;
  Int_t ncombi = 0;
  AliESDtrack *track1;
  AliESDtrack *track2;
  Double_t distCA;
  Double_t x, par[5];
  Double_t alpha, cs, sn;
  Double_t crosspoint[3];
  for(Int_t i=0; i<nacc; i++){
    track1 = (AliESDtrack*)fTrkArray.At(i);
    

    for(Int_t j=i+1; j<nacc; j++){
      track2 = (AliESDtrack*)fTrkArray.At(j);

      distCA=track2->PropagateToDCA(track1,field);

      if(fDCAcut<=0 ||(fDCAcut>0&&distCA<fDCAcut)){
	track1->GetExternalParameters(x,par);
	alpha=track1->GetAlpha();
	cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
	Double_t x1=x*cs - par[0]*sn;
	Double_t y1=x*sn + par[0]*cs;
	Double_t z1=par[1];
	Double_t sx1=sn*sn*track1->GetSigmaY2(), sy1=cs*cs*track1->GetSigmaY2(); 
	track2->GetExternalParameters(x,par);
	alpha=track2->GetAlpha();
	cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
	Double_t x2=x*cs - par[0]*sn;
	Double_t y2=x*sn + par[0]*cs;
	Double_t z2=par[1];
	Double_t sx2=sn*sn*track2->GetSigmaY2(), sy2=cs*cs*track2->GetSigmaY2();
	Double_t sz1=track1->GetSigmaZ2(), sz2=track2->GetSigmaZ2();
	Double_t wx1=sx2/(sx1+sx2), wx2=1.- wx1;
	Double_t wy1=sy2/(sy1+sy2), wy2=1.- wy1;
	Double_t wz1=sz2/(sz1+sz2), wz2=1.- wz1;
	crosspoint[0]=wx1*x1 + wx2*x2; 
	crosspoint[1]=wy1*y1 + wy2*y2; 
	crosspoint[2]=wz1*z1 + wz2*z2;

	ncombi++;
	for(Int_t jj=0;jj<3;jj++)aver[jj]+=crosspoint[jj];
	for(Int_t jj=0;jj<3;jj++)averquad[jj]+=(crosspoint[jj]*crosspoint[jj]);
      }
    }
      
  }
  if(ncombi>0){
    for(Int_t jj=0;jj<3;jj++){
      initPos[jj] = aver[jj]/ncombi;
      averquad[jj]/=ncombi;
      sigmaquad[jj]=averquad[jj]-initPos[jj]*initPos[jj];
      sigma+=sigmaquad[jj];
    }
    sigma=TMath::Sqrt(TMath::Abs(sigma));
  }
  else {
    Warning("HelixVertexFinder","Finder did not succed");
    sigma=999;
  }
  fVert.SetXYZ(initPos);
  fVert.SetDispersion(sigma);
  fVert.SetNContributors(ncombi);
}
//---------------------------------------------------------------------------
void AliVertexerTracks::StrLinVertexFinderMinDist(Int_t optUseWeights){

  // Calculate the point at minimum distance to prepared tracks 
  
  Double_t initPos[3];
  initPos[2] = 0.;
  Double_t sigma=0;
  for(Int_t i=0;i<2;i++)initPos[i]=fNominalPos[i];
  const Int_t knacc = (Int_t)fTrkArray.GetEntriesFast();
  Double_t field=GetField();

  AliESDtrack *track1;
  Double_t (*vectP0)[3]=new Double_t [knacc][3];
  Double_t (*vectP1)[3]=new Double_t [knacc][3];
  
  Double_t sum[3][3];
  Double_t dsum[3]={0,0,0};
  for(Int_t i=0;i<3;i++)
    for(Int_t j=0;j<3;j++)sum[i][j]=0;
  for(Int_t i=0; i<knacc; i++){
    track1 = (AliESDtrack*)fTrkArray.At(i);
    Double_t alpha=track1->GetAlpha();
    Double_t mindist = TMath::Cos(alpha)*fNominalPos[0]+TMath::Sin(alpha)*fNominalPos[1];

    Double_t pos[3]; track1->GetXYZAt(mindist,field,pos);
    Double_t dir[3]; track1->GetPxPyPzAt(mindist,field,dir);
    AliStrLine *line1 = new AliStrLine(pos,dir);

    Double_t p0[3],cd[3];
    line1->GetP0(p0);
    line1->GetCd(cd);
    Double_t p1[3]={p0[0]+cd[0],p0[1]+cd[1],p0[2]+cd[2]};
    vectP0[i][0]=p0[0];
    vectP0[i][1]=p0[1];
    vectP0[i][2]=p0[2];
    vectP1[i][0]=p1[0];
    vectP1[i][1]=p1[1];
    vectP1[i][2]=p1[2];
    
    Double_t matr[3][3];
    Double_t dknow[3];
    if(optUseWeights==0)GetStrLinDerivMatrix(p0,p1,matr,dknow);
    if(optUseWeights==1){
      Double_t sigmasq[3];
      sigmasq[0]=track1->GetSigmaY2();
      sigmasq[1]=track1->GetSigmaY2();
      sigmasq[2]=track1->GetSigmaZ2();
      GetStrLinDerivMatrix(p0,p1,sigmasq,matr,dknow);
    }

    for(Int_t iii=0;iii<3;iii++){
      dsum[iii]+=dknow[iii]; 
      for(Int_t lj=0;lj<3;lj++) sum[iii][lj]+=matr[iii][lj];
    }
    delete line1;
  }
  
  Double_t vett[3][3];
  Double_t det=GetDeterminant3X3(sum);
  
   if(det!=0){
     for(Int_t zz=0;zz<3;zz++){
       for(Int_t ww=0;ww<3;ww++){
	 for(Int_t kk=0;kk<3;kk++) vett[ww][kk]=sum[ww][kk];
       }
       for(Int_t kk=0;kk<3;kk++) vett[kk][zz]=dsum[kk];
       initPos[zz]=GetDeterminant3X3(vett)/det;
     }


     for(Int_t i=0; i<knacc; i++){
       Double_t p0[3]={0,0,0},p1[3]={0,0,0};
       for(Int_t ii=0;ii<3;ii++){
	 p0[ii]=vectP0[i][ii];
	 p1[ii]=vectP1[i][ii];
       }
       sigma+=GetStrLinMinDist(p0,p1,initPos);
     }

     sigma=TMath::Sqrt(sigma);
   }else{
    Warning("StrLinVertexFinderMinDist","Finder did not succed");
    sigma=999;
  }
  delete vectP0;
  delete vectP1;
  fVert.SetXYZ(initPos);
  fVert.SetDispersion(sigma);
  fVert.SetNContributors(knacc);
}
//_______________________________________________________________________
Double_t AliVertexerTracks::GetDeterminant3X3(Double_t matr[][3]){
  //
  Double_t det=matr[0][0]*matr[1][1]*matr[2][2]-matr[0][0]*matr[1][2]*matr[2][1]-matr[0][1]*matr[1][0]*matr[2][2]+matr[0][1]*matr[1][2]*matr[2][0]+matr[0][2]*matr[1][0]*matr[2][1]-matr[0][2]*matr[1][1]*matr[2][0];
 return det;
}
//____________________________________________________________________________
void AliVertexerTracks::GetStrLinDerivMatrix(Double_t *p0,Double_t *p1,Double_t m[][3],Double_t *d){

  //
  Double_t x12=p0[0]-p1[0];
  Double_t y12=p0[1]-p1[1];
  Double_t z12=p0[2]-p1[2];
  Double_t kk=x12*x12+y12*y12+z12*z12;
  m[0][0]=2-2/kk*x12*x12;
  m[0][1]=-2/kk*x12*y12;
  m[0][2]=-2/kk*x12*z12;
  m[1][0]=-2/kk*x12*y12;
  m[1][1]=2-2/kk*y12*y12;
  m[1][2]=-2/kk*y12*z12;
  m[2][0]=-2/kk*x12*z12;
  m[2][1]=-2*y12*z12;
  m[2][2]=2-2/kk*z12*z12;
  d[0]=2*p0[0]-2/kk*p0[0]*x12*x12-2/kk*p0[2]*x12*z12-2/kk*p0[1]*x12*y12;
  d[1]=2*p0[1]-2/kk*p0[1]*y12*y12-2/kk*p0[0]*x12*y12-2/kk*p0[2]*z12*y12;
  d[2]=2*p0[2]-2/kk*p0[2]*z12*z12-2/kk*p0[0]*x12*z12-2/kk*p0[1]*z12*y12;

}
//____________________________________________________________________________
void AliVertexerTracks::GetStrLinDerivMatrix(Double_t *p0,Double_t *p1,Double_t *sigmasq,Double_t m[][3],Double_t *d){
  //
  Double_t x12=p1[0]-p0[0];
  Double_t y12=p1[1]-p0[1];
  Double_t z12=p1[2]-p0[2];

  Double_t den= x12*x12*sigmasq[1]*sigmasq[2]+y12*y12*sigmasq[0]*sigmasq[2]+z12*z12*sigmasq[0]*sigmasq[1];

  Double_t kk= 2*(x12*x12/sigmasq[0]+y12*y12/sigmasq[1]+z12*z12/sigmasq[2]);

  Double_t cc[3];
  cc[0]=-x12/sigmasq[0];
  cc[1]=-y12/sigmasq[1];
  cc[2]=-z12/sigmasq[2];

  Double_t ww=(-p0[0]*x12*sigmasq[1]*sigmasq[2]-p0[1]*y12*sigmasq[0]*sigmasq[2]-p0[2]*z12*sigmasq[0]*sigmasq[1])/den;

  Double_t ss= -p0[0]*cc[0]-p0[1]*cc[1]-p0[2]*cc[2];

  Double_t aa[3];
  aa[0]=x12*sigmasq[1]*sigmasq[2]/den;
  aa[1]=y12*sigmasq[0]*sigmasq[2]/den;
  aa[2]=z12*sigmasq[0]*sigmasq[1]/den;

  m[0][0]=aa[0]*(aa[0]*kk+2*cc[0])+2*cc[0]*aa[0]+2/sigmasq[0];
  m[0][1]=aa[1]*(aa[0]*kk+2*cc[0])+2*cc[1]*aa[0];
  m[0][2]=aa[2]*(aa[0]*kk+2*cc[0])+2*cc[2]*aa[0];

  m[1][0]=aa[0]*(aa[1]*kk+2*cc[1])+2*cc[0]*aa[1];
  m[1][1]=aa[1]*(aa[1]*kk+2*cc[1])+2*cc[1]*aa[1]+2/sigmasq[1];
  m[1][2]=aa[2]*(aa[1]*kk+2*cc[1])+2*cc[2]*aa[1];

  m[2][0]=aa[0]*(aa[2]*kk+2*cc[2])+2*cc[0]*aa[2];
  m[2][1]=aa[1]*(aa[2]*kk+2*cc[2])+2*cc[1]*aa[2];
  m[2][2]=aa[2]*(aa[2]*kk+2*cc[2])+2*cc[2]*aa[2]+2/sigmasq[2];

  d[0]=-ww*(aa[0]*kk+2*cc[0])-2*ss*aa[0]+2*p0[0]/sigmasq[0];
  d[1]=-ww*(aa[1]*kk+2*cc[1])-2*ss*aa[1]+2*p0[1]/sigmasq[1];
  d[2]=-ww*(aa[2]*kk+2*cc[2])-2*ss*aa[2]+2*p0[2]/sigmasq[2];

}
//_____________________________________________________________________________
Double_t AliVertexerTracks::GetStrLinMinDist(Double_t *p0,Double_t *p1,Double_t *x0){
  //
  Double_t x12=p0[0]-p1[0];
  Double_t y12=p0[1]-p1[1];
  Double_t z12=p0[2]-p1[2];
  Double_t x10=p0[0]-x0[0];
  Double_t y10=p0[1]-x0[1];
  Double_t z10=p0[2]-x0[2];
  return ((x10*x10+y10*y10+z10*z10)*(x12*x12+y12*y12+z12*z12)-(x10*x12+y10*y12+z10*z12)*(x10*x12+y10*y12+z10*z12))/(x12*x12+y12*y12+z12*z12);
}
Commit	Line	Data
2d57349e	1	/**************************************************************************
	2	* Copyright(c) 1998-2003, ALICE Experiment at CERN, All rights reserved. *
	3	* *
	4	* Author: The ALICE Off-line Project. *
	5	* Contributors are mentioned in the code where appropriate. *
	6	* *
	7	* Permission to use, copy, modify and distribute this software and its *
	8	* documentation strictly for non-commercial purposes is hereby granted *
	9	* without fee, provided that the above copyright notice appears in all *
	10	* copies and that both the copyright notice and this permission notice *
	11	* appear in the supporting documentation. The authors make no claims *
	12	* about the suitability of this software for any purpose. It is *
	13	* provided "as is" without express or implied warranty. *
	14	**************************************************************************/
	15
	16	//-----------------------------------------------------------------
	17	// Implementation of the vertexer from ESD tracks
	18	//
	19	// Origin: AliITSVertexerTracks
	20	// A.Dainese, Padova,
	21	// andrea.dainese@pd.infn.it
	22	// M.Masera, Torino,
	23	// massimo.masera@to.infn.it
	24	// Moved to STEER and adapted to ESD tracks:
	25	// F.Prino, Torino, prino@to.infn.it
	26	//-----------------------------------------------------------------
	27
	28	//---- Root headers --------
	29	#include <TTree.h>
	30	//---- AliRoot headers -----
	31	#include "AliStrLine.h"
	32	#include "AliVertexerTracks.h"
c5e3e5d1	33	#include "AliESD.h"
2d57349e	34	#include "AliESDtrack.h"
	35
	36	ClassImp(AliVertexerTracks)
	37
	38
	39	//----------------------------------------------------------------------------
	40	AliVertexerTracks::AliVertexerTracks():
	41	TObject(),fVert()
	42	{
	43	//
	44	// Default constructor
	45	//
	46	SetVtxStart();
	47	SetMinTracks();
	48	fDCAcut=0;
	49	fAlgo=1;
	50	}
	51	//-----------------------------------------------------------------------------
	52	AliVertexerTracks::AliVertexerTracks(Double_t xStart, Double_t yStart):
	53	TObject(),fVert()
	54	{
	55	//
	56	// Standard constructor
	57	//
	58	SetVtxStart(xStart,yStart);
	59	SetMinTracks();
	60	fDCAcut=0;
	61	fAlgo=1;
	62	}
	63	//-----------------------------------------------------------------------------
	64	AliVertexerTracks::~AliVertexerTracks() {
	65	// Default Destructor
	66	// The objects poited by the following pointers are not owned
	67	// by this class and are not deleted
	68	}
	69	//----------------------------------------------------------------------------
	70	Int_t AliVertexerTracks::PrepareTracks(TTree &trkTree) {
	71	//
	72	// Propagate tracks to initial vertex position and store them in a TObjArray
	73	//
	74	Double_t alpha,xlStart;
	75	Int_t nTrks = 0;
	76
	77	Int_t nEntries = (Int_t)trkTree.GetEntries();
	78	if(!fTrkArray.IsEmpty()) fTrkArray.Clear();
	79	fTrkArray.Expand(nEntries);
	80
	81	for(Int_t i=0; i<nEntries; i++) {
	82	AliESDtrack *track = new AliESDtrack;
	83	trkTree.SetBranchAddress("tracks",&track);
	84	trkTree.GetEvent(i);
	85
	86	// propagate track to vtxSeed
	87	alpha = track->GetAlpha();
	88	xlStart = fNominalPos[0]TMath::Cos(alpha)+fNominalPos[1]TMath::Sin(alpha);
	89	track->PropagateTo(xlStart,GetField()); // to vtxSeed
	90	fTrkArray.AddLast(track);
	91	nTrks++;
	92	}
	93	return nTrks;
	94	}
	95	//----------------------------------------------------------------------------
	96	AliVertex* AliVertexerTracks::VertexForSelectedTracks(TTree *trkTree) {
	97	//
98	// Return vertex from tracks in trkTree
99	//
100
101	// get tracks and propagate them to initial vertex position
102	Int_t nTrks = PrepareTracks(*trkTree);
103	if(nTrks < fMinTracks) {
104	printf("TooFewTracks\n");
105	Double_t vtx[3]={0,0,0};
106	fVert.SetXYZ(vtx);
107	fVert.SetDispersion(999);
108	fVert.SetNContributors(-5);
109	return &fVert;
110	}
111
112	// Set initial vertex position from ESD
113	if(fAlgo==1) StrLinVertexFinderMinDist(1);
114	if(fAlgo==2) StrLinVertexFinderMinDist(0);
115	if(fAlgo==3) HelixVertexFinder();
116	if(fAlgo==4) VertexFinder(1);
117	if(fAlgo==5) VertexFinder(0);
118	return &fVert;
119	}
c5e3e5d1	120
	121	//----------------------------------------------------------------------------
	122	AliESDVertex* AliVertexerTracks::FindVertex(const AliESD *event) {
	123	//
	124	// This is a simple wrapping (by Jouri.Belikov@cern.ch) over the original
	125	// code by the authors of this class.
	126	//
	127	Int_t nt=event->GetNumberOfTracks(), nacc=0;
	128	while (nt--) {
	129	AliESDtrack *t=event->GetTrack(nt);
	130	if ((t->GetStatus()&AliESDtrack::kITSrefit)==0) continue;
	131	fTrkArray.AddLast(t);
	132	nacc++;
	133	}
	134
	135	// get tracks and propagate them to initial vertex position
	136	if(nacc < fMinTracks) {
	137	printf("TooFewTracks\n");
	138	Double_t vtx[3]={0,0,0};
	139	fVert.SetXYZ(vtx);
	140	fVert.SetDispersion(999);
	141	fVert.SetNContributors(-5);
	142	} else
	143	switch (fAlgo) {
	144	case 1: StrLinVertexFinderMinDist(1); break;
	145	case 2: StrLinVertexFinderMinDist(0); break;
	146	case 3: HelixVertexFinder(); break;
	147	case 4: VertexFinder(1); break;
	148	case 5: VertexFinder(0); break;
	149	default: printf("Wrong algorithm\n"); break;
	150	}
	151
	152	fTrkArray.Clear();
	153	return &fVert;
	154	}
	155
	156
2d57349e	157	//----------------------------------------------------------------------------
	158	AliVertex* AliVertexerTracks::VertexForSelectedTracks(TObjArray *trkArray) {
	159	//
	160	// Return vertex from array of tracks
	161	//
	162
	163	// get tracks and propagate them to initial vertex position
	164	Int_t nTrks = trkArray->GetEntriesFast();
	165	if(nTrks < fMinTracks) {
	166	printf("TooFewTracks\n");
	167	Double_t vtx[3]={0,0,0};
	168	fVert.SetXYZ(vtx);
	169	fVert.SetDispersion(999);
	170	fVert.SetNContributors(-5);
	171	return &fVert;
	172	}
	173	TTree *trkTree = new TTree("TreeT","tracks");
	174	AliESDtrack *esdTrack = 0;
	175	trkTree->Branch("tracks","AliESDtrack",&esdTrack);
	176	for(Int_t i=0; i<nTrks; i++){
	177	esdTrack = (AliESDtrack*)trkArray->At(i);
	178	trkTree->Fill();
	179	}
	180
2e5c8fc7	181	AliVertex *vtx = VertexForSelectedTracks(trkTree);
	182	delete trkTree;
	183	return vtx;
2d57349e	184	}
	185
	186	//---------------------------------------------------------------------------
	187	void AliVertexerTracks::VertexFinder(Int_t optUseWeights) {
	188
	189	// Get estimate of vertex position in (x,y) from tracks DCA
	190
	191	Double_t initPos[3];
	192	initPos[2] = 0.;
	193	for(Int_t i=0;i<2;i++)initPos[i]=fNominalPos[i];
	194	Int_t nacc = (Int_t)fTrkArray.GetEntriesFast();
	195	Double_t aver[3]={0.,0.,0.};
	196	Double_t aversq[3]={0.,0.,0.};
	197	Double_t sigmasq[3]={0.,0.,0.};
	198	Double_t sigma=0;
	199	Int_t ncombi = 0;
	200	AliESDtrack *track1;
	201	AliESDtrack *track2;
	202	Double_t alpha,mindist;
	203	Double_t field=GetField();
	204
	205	for(Int_t i=0; i<nacc; i++){
	206	track1 = (AliESDtrack*)fTrkArray.At(i);
	207	alpha=track1->GetAlpha();
	208	mindist = TMath::Cos(alpha)fNominalPos[0]+TMath::Sin(alpha)fNominalPos[1];
08df6187	209
	210	Double_t pos[3]; track1->GetXYZAt(mindist,field,pos);
	211	Double_t dir[3]; track1->GetPxPyPzAt(mindist,field,dir);
	212	AliStrLine *line1 = new AliStrLine(pos,dir);
2d57349e	213
	214	for(Int_t j=i+1; j<nacc; j++){
	215	track2 = (AliESDtrack*)fTrkArray.At(j);
	216	alpha=track2->GetAlpha();
	217	mindist = TMath::Cos(alpha)fNominalPos[0]+TMath::Sin(alpha)fNominalPos[1];
08df6187	218
	219	Double_t pos[3]; track2->GetXYZAt(mindist,field,pos);
	220	Double_t dir[3]; track2->GetPxPyPzAt(mindist,field,dir);
	221	AliStrLine *line2 = new AliStrLine(pos,dir);
	222
2d57349e	223	Double_t distCA=line2->GetDCA(line1);
	224	if(fDCAcut<=0 \|\| (fDCAcut>0&&distCA<fDCAcut)){
	225	Double_t pnt1[3],pnt2[3],crosspoint[3];
	226
	227	if(optUseWeights<=0){
	228	Int_t retcode = line2->Cross(line1,crosspoint);
	229	if(retcode>=0){
	230	ncombi++;
	231	for(Int_t jj=0;jj<3;jj++)aver[jj]+=crosspoint[jj];
	232	for(Int_t jj=0;jj<3;jj++)aversq[jj]+=(crosspoint[jj]*crosspoint[jj]);
	233	}
	234	}
	235	if(optUseWeights>0){
	236	Int_t retcode = line1->CrossPoints(line2,pnt1,pnt2);
	237	if(retcode>=0){
	238	Double_t alpha, cs, sn;
	239	alpha=track1->GetAlpha();
	240	cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
	241	Double_t sx1=snsntrack1->GetSigmaY2(), sy1=cscstrack1->GetSigmaY2();
	242	alpha=track2->GetAlpha();
	243	cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
	244	Double_t sx2=snsntrack2->GetSigmaY2(), sy2=cscstrack2->GetSigmaY2();
	245	Double_t sz1=track1->GetSigmaZ2(), sz2=track2->GetSigmaZ2();
	246	Double_t wx1=sx2/(sx1+sx2), wx2=1.- wx1;
	247	Double_t wy1=sy2/(sy1+sy2), wy2=1.- wy1;
	248	Double_t wz1=sz2/(sz1+sz2), wz2=1.- wz1;
	249	crosspoint[0]=wx1pnt1[0] + wx2pnt2[0];
	250	crosspoint[1]=wy1pnt1[1] + wy2pnt2[1];
	251	crosspoint[2]=wz1pnt1[2] + wz2pnt2[2];
	252
	253	ncombi++;
	254	for(Int_t jj=0;jj<3;jj++)aver[jj]+=crosspoint[jj];
	255	for(Int_t jj=0;jj<3;jj++)aversq[jj]+=(crosspoint[jj]*crosspoint[jj]);
	256	}
	257	}
	258	}
	259	delete line2;
	260	}
	261	delete line1;
	262	}
	263	if(ncombi>0){
	264	for(Int_t jj=0;jj<3;jj++){
	265	initPos[jj] = aver[jj]/ncombi;
	266	aversq[jj]/=ncombi;
	267	sigmasq[jj]=aversq[jj]-initPos[jj]*initPos[jj];
	268	sigma+=sigmasq[jj];
	269	}
	270	sigma=TMath::Sqrt(TMath::Abs(sigma));
	271	}
	272	else {
	273	Warning("VertexFinder","Finder did not succed");
	274	sigma=999;
	275	}
	276	fVert.SetXYZ(initPos);
	277	fVert.SetDispersion(sigma);
	278	fVert.SetNContributors(ncombi);
	279	}
	280	//---------------------------------------------------------------------------
	281	void AliVertexerTracks::HelixVertexFinder() {
	282
	283	// Get estimate of vertex position in (x,y) from tracks DCA
	284
	285
	286	Double_t initPos[3];
287	initPos[2] = 0.;
288	for(Int_t i=0;i<2;i++)initPos[i]=fNominalPos[i];
289	Double_t field=GetField();
290
291	Int_t nacc = (Int_t)fTrkArray.GetEntriesFast();
292
293	Double_t aver[3]={0.,0.,0.};
294	Double_t averquad[3]={0.,0.,0.};
295	Double_t sigmaquad[3]={0.,0.,0.};
296	Double_t sigma=0;
297	Int_t ncombi = 0;
298	AliESDtrack *track1;
299	AliESDtrack *track2;
300	Double_t distCA;
301	Double_t x, par[5];
302	Double_t alpha, cs, sn;
303	Double_t crosspoint[3];
304	for(Int_t i=0; i<nacc; i++){
305	track1 = (AliESDtrack*)fTrkArray.At(i);
306
307
308	for(Int_t j=i+1; j<nacc; j++){
309	track2 = (AliESDtrack*)fTrkArray.At(j);
310
311	distCA=track2->PropagateToDCA(track1,field);
312
313	if(fDCAcut<=0 \|\|(fDCAcut>0&&distCA<fDCAcut)){
314	track1->GetExternalParameters(x,par);
315	alpha=track1->GetAlpha();
316	cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
317	Double_t x1=xcs - par[0]sn;
318	Double_t y1=xsn + par[0]cs;
319	Double_t z1=par[1];
320	Double_t sx1=snsntrack1->GetSigmaY2(), sy1=cscstrack1->GetSigmaY2();
321	track2->GetExternalParameters(x,par);
322	alpha=track2->GetAlpha();
323	cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
324	Double_t x2=xcs - par[0]sn;
325	Double_t y2=xsn + par[0]cs;
326	Double_t z2=par[1];
327	Double_t sx2=snsntrack2->GetSigmaY2(), sy2=cscstrack2->GetSigmaY2();
328	Double_t sz1=track1->GetSigmaZ2(), sz2=track2->GetSigmaZ2();
329	Double_t wx1=sx2/(sx1+sx2), wx2=1.- wx1;
330	Double_t wy1=sy2/(sy1+sy2), wy2=1.- wy1;
331	Double_t wz1=sz2/(sz1+sz2), wz2=1.- wz1;
332	crosspoint[0]=wx1x1 + wx2x2;
333	crosspoint[1]=wy1y1 + wy2y2;
334	crosspoint[2]=wz1z1 + wz2z2;
335
336	ncombi++;
337	for(Int_t jj=0;jj<3;jj++)aver[jj]+=crosspoint[jj];
338	for(Int_t jj=0;jj<3;jj++)averquad[jj]+=(crosspoint[jj]*crosspoint[jj]);
339	}
340	}
341
342	}
343	if(ncombi>0){
344	for(Int_t jj=0;jj<3;jj++){
345	initPos[jj] = aver[jj]/ncombi;
346	averquad[jj]/=ncombi;
347	sigmaquad[jj]=averquad[jj]-initPos[jj]*initPos[jj];
348	sigma+=sigmaquad[jj];
349	}
350	sigma=TMath::Sqrt(TMath::Abs(sigma));
351	}
352	else {
353	Warning("HelixVertexFinder","Finder did not succed");
354	sigma=999;
355	}
356	fVert.SetXYZ(initPos);
357	fVert.SetDispersion(sigma);
358	fVert.SetNContributors(ncombi);
359	}
360	//---------------------------------------------------------------------------
361	void AliVertexerTracks::StrLinVertexFinderMinDist(Int_t optUseWeights){
362
363	// Calculate the point at minimum distance to prepared tracks
364
365	Double_t initPos[3];
366	initPos[2] = 0.;
367	Double_t sigma=0;
368	for(Int_t i=0;i<2;i++)initPos[i]=fNominalPos[i];
369	const Int_t knacc = (Int_t)fTrkArray.GetEntriesFast();
370	Double_t field=GetField();
371
372	AliESDtrack *track1;
373	Double_t (*vectP0)[3]=new Double_t [knacc][3];
374	Double_t (*vectP1)[3]=new Double_t [knacc][3];
375
376	Double_t sum[3][3];
377	Double_t dsum[3]={0,0,0};
378	for(Int_t i=0;i<3;i++)
379	for(Int_t j=0;j<3;j++)sum[i][j]=0;
380	for(Int_t i=0; i<knacc; i++){
381	track1 = (AliESDtrack*)fTrkArray.At(i);
382	Double_t alpha=track1->GetAlpha();
383	Double_t mindist = TMath::Cos(alpha)fNominalPos[0]+TMath::Sin(alpha)fNominalPos[1];
08df6187	384
08df6187	385	Double_t pos[3]; track1->GetXYZAt(mindist,field,pos);
7f101aa0	386	Double_t dir[3]; track1->GetPxPyPzAt(mindist,field,dir);
08df6187	387	AliStrLine *line1 = new AliStrLine(pos,dir);
2d57349e	388
	389	Double_t p0[3],cd[3];
	390	line1->GetP0(p0);
	391	line1->GetCd(cd);
	392	Double_t p1[3]={p0[0]+cd[0],p0[1]+cd[1],p0[2]+cd[2]};
	393	vectP0[i][0]=p0[0];
	394	vectP0[i][1]=p0[1];
	395	vectP0[i][2]=p0[2];
	396	vectP1[i][0]=p1[0];
	397	vectP1[i][1]=p1[1];
	398	vectP1[i][2]=p1[2];
	399
	400	Double_t matr[3][3];
	401	Double_t dknow[3];
	402	if(optUseWeights==0)GetStrLinDerivMatrix(p0,p1,matr,dknow);
	403	if(optUseWeights==1){
	404	Double_t sigmasq[3];
	405	sigmasq[0]=track1->GetSigmaY2();
	406	sigmasq[1]=track1->GetSigmaY2();
	407	sigmasq[2]=track1->GetSigmaZ2();
	408	GetStrLinDerivMatrix(p0,p1,sigmasq,matr,dknow);
	409	}
	410
	411	for(Int_t iii=0;iii<3;iii++){
	412	dsum[iii]+=dknow[iii];
	413	for(Int_t lj=0;lj<3;lj++) sum[iii][lj]+=matr[iii][lj];
	414	}
	415	delete line1;
	416	}
	417
	418	Double_t vett[3][3];
	419	Double_t det=GetDeterminant3X3(sum);
	420
	421	if(det!=0){
	422	for(Int_t zz=0;zz<3;zz++){
	423	for(Int_t ww=0;ww<3;ww++){
	424	for(Int_t kk=0;kk<3;kk++) vett[ww][kk]=sum[ww][kk];
	425	}
	426	for(Int_t kk=0;kk<3;kk++) vett[kk][zz]=dsum[kk];
	427	initPos[zz]=GetDeterminant3X3(vett)/det;
	428	}
	429
	430
	431	for(Int_t i=0; i<knacc; i++){
	432	Double_t p0[3]={0,0,0},p1[3]={0,0,0};
	433	for(Int_t ii=0;ii<3;ii++){
	434	p0[ii]=vectP0[i][ii];
	435	p1[ii]=vectP1[i][ii];
	436	}
	437	sigma+=GetStrLinMinDist(p0,p1,initPos);
	438	}
	439
	440	sigma=TMath::Sqrt(sigma);
	441	}else{
	442	Warning("StrLinVertexFinderMinDist","Finder did not succed");
	443	sigma=999;
	444	}
	445	delete vectP0;
	446	delete vectP1;
	447	fVert.SetXYZ(initPos);
	448	fVert.SetDispersion(sigma);
	449	fVert.SetNContributors(knacc);
	450	}
	451	//_______________________________________________________________________
452	Double_t AliVertexerTracks::GetDeterminant3X3(Double_t matr[][3]){
453	//
454	Double_t det=matr[0][0]matr[1][1]matr[2][2]-matr[0][0]matr[1][2]matr[2][1]-matr[0][1]matr[1][0]matr[2][2]+matr[0][1]matr[1][2]matr[2][0]+matr[0][2]matr[1][0]matr[2][1]-matr[0][2]matr[1][1]matr[2][0];
455	return det;
456	}
457	//____________________________________________________________________________
458	void AliVertexerTracks::GetStrLinDerivMatrix(Double_t p0,Double_t p1,Double_t m[][3],Double_t *d){
459
460	//
461	Double_t x12=p0[0]-p1[0];
462	Double_t y12=p0[1]-p1[1];
463	Double_t z12=p0[2]-p1[2];
464	Double_t kk=x12x12+y12y12+z12*z12;
465	m[0][0]=2-2/kkx12x12;
466	m[0][1]=-2/kkx12y12;
467	m[0][2]=-2/kkx12z12;
468	m[1][0]=-2/kkx12y12;
469	m[1][1]=2-2/kky12y12;
470	m[1][2]=-2/kky12z12;
471	m[2][0]=-2/kkx12z12;
472	m[2][1]=-2y12z12;
473	m[2][2]=2-2/kkz12z12;
474	d[0]=2p0[0]-2/kkp0[0]x12x12-2/kkp0[2]x12z12-2/kkp0[1]x12y12;
475	d[1]=2p0[1]-2/kkp0[1]y12y12-2/kkp0[0]x12y12-2/kkp0[2]z12y12;
476	d[2]=2p0[2]-2/kkp0[2]z12z12-2/kkp0[0]x12z12-2/kkp0[1]z12y12;
477
478	}
479	//____________________________________________________________________________
480	void AliVertexerTracks::GetStrLinDerivMatrix(Double_t p0,Double_t p1,Double_t sigmasq,Double_t m[][3],Double_t d){
481	//
482	Double_t x12=p1[0]-p0[0];
483	Double_t y12=p1[1]-p0[1];
484	Double_t z12=p1[2]-p0[2];
485
486	Double_t den= x12x12sigmasq[1]sigmasq[2]+y12y12sigmasq[0]sigmasq[2]+z12z12sigmasq[0]*sigmasq[1];
487
488	Double_t kk= 2(x12x12/sigmasq[0]+y12y12/sigmasq[1]+z12z12/sigmasq[2]);
489
490	Double_t cc[3];
491	cc[0]=-x12/sigmasq[0];
492	cc[1]=-y12/sigmasq[1];
493	cc[2]=-z12/sigmasq[2];
494
495	Double_t ww=(-p0[0]x12sigmasq[1]sigmasq[2]-p0[1]y12sigmasq[0]sigmasq[2]-p0[2]z12sigmasq[0]*sigmasq[1])/den;
496
497	Double_t ss= -p0[0]cc[0]-p0[1]cc[1]-p0[2]*cc[2];
498
499	Double_t aa[3];
500	aa[0]=x12sigmasq[1]sigmasq[2]/den;
501	aa[1]=y12sigmasq[0]sigmasq[2]/den;
502	aa[2]=z12sigmasq[0]sigmasq[1]/den;
503
504	m[0][0]=aa[0](aa[0]kk+2cc[0])+2cc[0]*aa[0]+2/sigmasq[0];
505	m[0][1]=aa[1](aa[0]kk+2cc[0])+2cc[1]*aa[0];
506	m[0][2]=aa[2](aa[0]kk+2cc[0])+2cc[2]*aa[0];
507
508	m[1][0]=aa[0](aa[1]kk+2cc[1])+2cc[0]*aa[1];
509	m[1][1]=aa[1](aa[1]kk+2cc[1])+2cc[1]*aa[1]+2/sigmasq[1];
510	m[1][2]=aa[2](aa[1]kk+2cc[1])+2cc[2]*aa[1];
511
512	m[2][0]=aa[0](aa[2]kk+2cc[2])+2cc[0]*aa[2];
513	m[2][1]=aa[1](aa[2]kk+2cc[2])+2cc[1]*aa[2];
514	m[2][2]=aa[2](aa[2]kk+2cc[2])+2cc[2]*aa[2]+2/sigmasq[2];
515
516	d[0]=-ww(aa[0]kk+2cc[0])-2ssaa[0]+2p0[0]/sigmasq[0];
517	d[1]=-ww(aa[1]kk+2cc[1])-2ssaa[1]+2p0[1]/sigmasq[1];
518	d[2]=-ww(aa[2]kk+2cc[2])-2ssaa[2]+2p0[2]/sigmasq[2];
519
520	}
521	//_____________________________________________________________________________
522	Double_t AliVertexerTracks::GetStrLinMinDist(Double_t p0,Double_t p1,Double_t *x0){
523	//
524	Double_t x12=p0[0]-p1[0];
525	Double_t y12=p0[1]-p1[1];
526	Double_t z12=p0[2]-p1[2];
527	Double_t x10=p0[0]-x0[0];
528	Double_t y10=p0[1]-x0[1];
529	Double_t z10=p0[2]-x0[2];
530	return ((x10x10+y10y10+z10z10)(x12x12+y12y12+z12z12)-(x10x12+y10y12+z10z12)(x10x12+y10y12+z10z12))/(x12x12+y12y12+z12*z12);
531	}