[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 "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;
}
//----------------------------------------------------------------------------
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();
  }
    
  return VertexForSelectedTracks(trkTree);
}

//---------------------------------------------------------------------------
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];
    AliStrLine *line1 = new AliStrLine();
    track1->ApproximateHelixWithLine(mindist,field,line1);
   
    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];
      AliStrLine *line2 = new AliStrLine();
      track2->ApproximateHelixWithLine(mindist,field,line2);
      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];
    AliStrLine *line1 = new AliStrLine();
    track1->ApproximateHelixWithLine(mindist,field,line1);

    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"
	33	#include "AliESDtrack.h"
	34
	35	ClassImp(AliVertexerTracks)
	36
	37
	38	//----------------------------------------------------------------------------
	39	AliVertexerTracks::AliVertexerTracks():
	40	TObject(),fVert()
	41	{
	42	//
	43	// Default constructor
	44	//
	45	SetVtxStart();
	46	SetMinTracks();
	47	fDCAcut=0;
	48	fAlgo=1;
	49	}
	50	//-----------------------------------------------------------------------------
	51	AliVertexerTracks::AliVertexerTracks(Double_t xStart, Double_t yStart):
	52	TObject(),fVert()
	53	{
	54	//
	55	// Standard constructor
	56	//
	57	SetVtxStart(xStart,yStart);
	58	SetMinTracks();
	59	fDCAcut=0;
	60	fAlgo=1;
	61	}
	62	//-----------------------------------------------------------------------------
	63	AliVertexerTracks::~AliVertexerTracks() {
	64	// Default Destructor
65	// The objects poited by the following pointers are not owned
66	// by this class and are not deleted
67	}
68	//----------------------------------------------------------------------------
69	Int_t AliVertexerTracks::PrepareTracks(TTree &trkTree) {
70	//
71	// Propagate tracks to initial vertex position and store them in a TObjArray
72	//
73	Double_t alpha,xlStart;
74	Int_t nTrks = 0;
75
76	Int_t nEntries = (Int_t)trkTree.GetEntries();
77	if(!fTrkArray.IsEmpty()) fTrkArray.Clear();
78	fTrkArray.Expand(nEntries);
79
80	for(Int_t i=0; i<nEntries; i++) {
81	AliESDtrack *track = new AliESDtrack;
82	trkTree.SetBranchAddress("tracks",&track);
83	trkTree.GetEvent(i);
84
85	// propagate track to vtxSeed
86	alpha = track->GetAlpha();
87	xlStart = fNominalPos[0]TMath::Cos(alpha)+fNominalPos[1]TMath::Sin(alpha);
88	track->PropagateTo(xlStart,GetField()); // to vtxSeed
89	fTrkArray.AddLast(track);
90	nTrks++;
91	}
92	return nTrks;
93	}
94	//----------------------------------------------------------------------------
95	AliVertex* AliVertexerTracks::VertexForSelectedTracks(TTree *trkTree) {
96	//
97	// Return vertex from tracks in trkTree
98	//
99
100	// get tracks and propagate them to initial vertex position
101	Int_t nTrks = PrepareTracks(*trkTree);
102	if(nTrks < fMinTracks) {
103	printf("TooFewTracks\n");
104	Double_t vtx[3]={0,0,0};
105	fVert.SetXYZ(vtx);
106	fVert.SetDispersion(999);
107	fVert.SetNContributors(-5);
108	return &fVert;
109	}
110
111	// Set initial vertex position from ESD
112	if(fAlgo==1) StrLinVertexFinderMinDist(1);
113	if(fAlgo==2) StrLinVertexFinderMinDist(0);
114	if(fAlgo==3) HelixVertexFinder();
115	if(fAlgo==4) VertexFinder(1);
116	if(fAlgo==5) VertexFinder(0);
117	return &fVert;
118	}
119	//----------------------------------------------------------------------------
120	AliVertex* AliVertexerTracks::VertexForSelectedTracks(TObjArray *trkArray) {
121	//
122	// Return vertex from array of tracks
123	//
124
125	// get tracks and propagate them to initial vertex position
126	Int_t nTrks = trkArray->GetEntriesFast();
127	if(nTrks < fMinTracks) {
128	printf("TooFewTracks\n");
129	Double_t vtx[3]={0,0,0};
130	fVert.SetXYZ(vtx);
131	fVert.SetDispersion(999);
132	fVert.SetNContributors(-5);
133	return &fVert;
134	}
135	TTree *trkTree = new TTree("TreeT","tracks");
136	AliESDtrack *esdTrack = 0;
137	trkTree->Branch("tracks","AliESDtrack",&esdTrack);
138	for(Int_t i=0; i<nTrks; i++){
139	esdTrack = (AliESDtrack*)trkArray->At(i);
140	trkTree->Fill();
141	}
142
143	return VertexForSelectedTracks(trkTree);
144	}
145
146	//---------------------------------------------------------------------------
147	void AliVertexerTracks::VertexFinder(Int_t optUseWeights) {
148
149	// Get estimate of vertex position in (x,y) from tracks DCA
150
151	Double_t initPos[3];
152	initPos[2] = 0.;
153	for(Int_t i=0;i<2;i++)initPos[i]=fNominalPos[i];
154	Int_t nacc = (Int_t)fTrkArray.GetEntriesFast();
155	Double_t aver[3]={0.,0.,0.};
156	Double_t aversq[3]={0.,0.,0.};
157	Double_t sigmasq[3]={0.,0.,0.};
158	Double_t sigma=0;
159	Int_t ncombi = 0;
160	AliESDtrack *track1;
161	AliESDtrack *track2;
162	Double_t alpha,mindist;
163	Double_t field=GetField();
164
165	for(Int_t i=0; i<nacc; i++){
166	track1 = (AliESDtrack*)fTrkArray.At(i);
167	alpha=track1->GetAlpha();
168	mindist = TMath::Cos(alpha)fNominalPos[0]+TMath::Sin(alpha)fNominalPos[1];
169	AliStrLine *line1 = new AliStrLine();
170	track1->ApproximateHelixWithLine(mindist,field,line1);
171
172	for(Int_t j=i+1; j<nacc; j++){
173	track2 = (AliESDtrack*)fTrkArray.At(j);
174	alpha=track2->GetAlpha();
175	mindist = TMath::Cos(alpha)fNominalPos[0]+TMath::Sin(alpha)fNominalPos[1];
176	AliStrLine *line2 = new AliStrLine();
177	track2->ApproximateHelixWithLine(mindist,field,line2);
178	Double_t distCA=line2->GetDCA(line1);
179	if(fDCAcut<=0 \|\| (fDCAcut>0&&distCA<fDCAcut)){
180	Double_t pnt1[3],pnt2[3],crosspoint[3];
181
182	if(optUseWeights<=0){
183	Int_t retcode = line2->Cross(line1,crosspoint);
184	if(retcode>=0){
185	ncombi++;
186	for(Int_t jj=0;jj<3;jj++)aver[jj]+=crosspoint[jj];
187	for(Int_t jj=0;jj<3;jj++)aversq[jj]+=(crosspoint[jj]*crosspoint[jj]);
188	}
189	}
190	if(optUseWeights>0){
191	Int_t retcode = line1->CrossPoints(line2,pnt1,pnt2);
192	if(retcode>=0){
193	Double_t alpha, cs, sn;
194	alpha=track1->GetAlpha();
195	cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
196	Double_t sx1=snsntrack1->GetSigmaY2(), sy1=cscstrack1->GetSigmaY2();
197	alpha=track2->GetAlpha();
198	cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
199	Double_t sx2=snsntrack2->GetSigmaY2(), sy2=cscstrack2->GetSigmaY2();
200	Double_t sz1=track1->GetSigmaZ2(), sz2=track2->GetSigmaZ2();
201	Double_t wx1=sx2/(sx1+sx2), wx2=1.- wx1;
202	Double_t wy1=sy2/(sy1+sy2), wy2=1.- wy1;
203	Double_t wz1=sz2/(sz1+sz2), wz2=1.- wz1;
204	crosspoint[0]=wx1pnt1[0] + wx2pnt2[0];
205	crosspoint[1]=wy1pnt1[1] + wy2pnt2[1];
206	crosspoint[2]=wz1pnt1[2] + wz2pnt2[2];
207
208	ncombi++;
209	for(Int_t jj=0;jj<3;jj++)aver[jj]+=crosspoint[jj];
210	for(Int_t jj=0;jj<3;jj++)aversq[jj]+=(crosspoint[jj]*crosspoint[jj]);
211	}
212	}
213	}
214	delete line2;
215	}
216	delete line1;
217	}
218	if(ncombi>0){
219	for(Int_t jj=0;jj<3;jj++){
220	initPos[jj] = aver[jj]/ncombi;
221	aversq[jj]/=ncombi;
222	sigmasq[jj]=aversq[jj]-initPos[jj]*initPos[jj];
223	sigma+=sigmasq[jj];
224	}
225	sigma=TMath::Sqrt(TMath::Abs(sigma));
226	}
227	else {
228	Warning("VertexFinder","Finder did not succed");
229	sigma=999;
230	}
231	fVert.SetXYZ(initPos);
232	fVert.SetDispersion(sigma);
233	fVert.SetNContributors(ncombi);
234	}
235	//---------------------------------------------------------------------------
236	void AliVertexerTracks::HelixVertexFinder() {
237
238	// Get estimate of vertex position in (x,y) from tracks DCA
239
240
241	Double_t initPos[3];
242	initPos[2] = 0.;
243	for(Int_t i=0;i<2;i++)initPos[i]=fNominalPos[i];
244	Double_t field=GetField();
245
246	Int_t nacc = (Int_t)fTrkArray.GetEntriesFast();
247
248	Double_t aver[3]={0.,0.,0.};
249	Double_t averquad[3]={0.,0.,0.};
250	Double_t sigmaquad[3]={0.,0.,0.};
251	Double_t sigma=0;
252	Int_t ncombi = 0;
253	AliESDtrack *track1;
254	AliESDtrack *track2;
255	Double_t distCA;
256	Double_t x, par[5];
257	Double_t alpha, cs, sn;
258	Double_t crosspoint[3];
259	for(Int_t i=0; i<nacc; i++){
260	track1 = (AliESDtrack*)fTrkArray.At(i);
261
262
263	for(Int_t j=i+1; j<nacc; j++){
264	track2 = (AliESDtrack*)fTrkArray.At(j);
265
266	distCA=track2->PropagateToDCA(track1,field);
267
268	if(fDCAcut<=0 \|\|(fDCAcut>0&&distCA<fDCAcut)){
269	track1->GetExternalParameters(x,par);
270	alpha=track1->GetAlpha();
271	cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
272	Double_t x1=xcs - par[0]sn;
273	Double_t y1=xsn + par[0]cs;
274	Double_t z1=par[1];
275	Double_t sx1=snsntrack1->GetSigmaY2(), sy1=cscstrack1->GetSigmaY2();
276	track2->GetExternalParameters(x,par);
277	alpha=track2->GetAlpha();
278	cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
279	Double_t x2=xcs - par[0]sn;
280	Double_t y2=xsn + par[0]cs;
281	Double_t z2=par[1];
282	Double_t sx2=snsntrack2->GetSigmaY2(), sy2=cscstrack2->GetSigmaY2();
283	Double_t sz1=track1->GetSigmaZ2(), sz2=track2->GetSigmaZ2();
284	Double_t wx1=sx2/(sx1+sx2), wx2=1.- wx1;
285	Double_t wy1=sy2/(sy1+sy2), wy2=1.- wy1;
286	Double_t wz1=sz2/(sz1+sz2), wz2=1.- wz1;
287	crosspoint[0]=wx1x1 + wx2x2;
288	crosspoint[1]=wy1y1 + wy2y2;
289	crosspoint[2]=wz1z1 + wz2z2;
290
291	ncombi++;
292	for(Int_t jj=0;jj<3;jj++)aver[jj]+=crosspoint[jj];
293	for(Int_t jj=0;jj<3;jj++)averquad[jj]+=(crosspoint[jj]*crosspoint[jj]);
294	}
295	}
296
297	}
298	if(ncombi>0){
299	for(Int_t jj=0;jj<3;jj++){
300	initPos[jj] = aver[jj]/ncombi;
301	averquad[jj]/=ncombi;
302	sigmaquad[jj]=averquad[jj]-initPos[jj]*initPos[jj];
303	sigma+=sigmaquad[jj];
304	}
305	sigma=TMath::Sqrt(TMath::Abs(sigma));
306	}
307	else {
308	Warning("HelixVertexFinder","Finder did not succed");
309	sigma=999;
310	}
311	fVert.SetXYZ(initPos);
312	fVert.SetDispersion(sigma);
313	fVert.SetNContributors(ncombi);
314	}
315	//---------------------------------------------------------------------------
316	void AliVertexerTracks::StrLinVertexFinderMinDist(Int_t optUseWeights){
317
318	// Calculate the point at minimum distance to prepared tracks
319
320	Double_t initPos[3];
321	initPos[2] = 0.;
322	Double_t sigma=0;
323	for(Int_t i=0;i<2;i++)initPos[i]=fNominalPos[i];
324	const Int_t knacc = (Int_t)fTrkArray.GetEntriesFast();
325	Double_t field=GetField();
326
327	AliESDtrack *track1;
328	Double_t (*vectP0)[3]=new Double_t [knacc][3];
329	Double_t (*vectP1)[3]=new Double_t [knacc][3];
330
331	Double_t sum[3][3];
332	Double_t dsum[3]={0,0,0};
333	for(Int_t i=0;i<3;i++)
334	for(Int_t j=0;j<3;j++)sum[i][j]=0;
335	for(Int_t i=0; i<knacc; i++){
336	track1 = (AliESDtrack*)fTrkArray.At(i);
337	Double_t alpha=track1->GetAlpha();
338	Double_t mindist = TMath::Cos(alpha)fNominalPos[0]+TMath::Sin(alpha)fNominalPos[1];
339	AliStrLine *line1 = new AliStrLine();
340	track1->ApproximateHelixWithLine(mindist,field,line1);
341
342	Double_t p0[3],cd[3];
343	line1->GetP0(p0);
344	line1->GetCd(cd);
345	Double_t p1[3]={p0[0]+cd[0],p0[1]+cd[1],p0[2]+cd[2]};
346	vectP0[i][0]=p0[0];
347	vectP0[i][1]=p0[1];
348	vectP0[i][2]=p0[2];
349	vectP1[i][0]=p1[0];
350	vectP1[i][1]=p1[1];
351	vectP1[i][2]=p1[2];
352
353	Double_t matr[3][3];
354	Double_t dknow[3];
355	if(optUseWeights==0)GetStrLinDerivMatrix(p0,p1,matr,dknow);
356	if(optUseWeights==1){
357	Double_t sigmasq[3];
358	sigmasq[0]=track1->GetSigmaY2();
359	sigmasq[1]=track1->GetSigmaY2();
360	sigmasq[2]=track1->GetSigmaZ2();
361	GetStrLinDerivMatrix(p0,p1,sigmasq,matr,dknow);
362	}
363
364	for(Int_t iii=0;iii<3;iii++){
365	dsum[iii]+=dknow[iii];
366	for(Int_t lj=0;lj<3;lj++) sum[iii][lj]+=matr[iii][lj];
367	}
368	delete line1;
369	}
370
371	Double_t vett[3][3];
372	Double_t det=GetDeterminant3X3(sum);
373
374	if(det!=0){
375	for(Int_t zz=0;zz<3;zz++){
376	for(Int_t ww=0;ww<3;ww++){
377	for(Int_t kk=0;kk<3;kk++) vett[ww][kk]=sum[ww][kk];
378	}
379	for(Int_t kk=0;kk<3;kk++) vett[kk][zz]=dsum[kk];
380	initPos[zz]=GetDeterminant3X3(vett)/det;
381	}
382
383
384	for(Int_t i=0; i<knacc; i++){
385	Double_t p0[3]={0,0,0},p1[3]={0,0,0};
386	for(Int_t ii=0;ii<3;ii++){
387	p0[ii]=vectP0[i][ii];
388	p1[ii]=vectP1[i][ii];
389	}
390	sigma+=GetStrLinMinDist(p0,p1,initPos);
391	}
392
393	sigma=TMath::Sqrt(sigma);
394	}else{
395	Warning("StrLinVertexFinderMinDist","Finder did not succed");
396	sigma=999;
397	}
398	delete vectP0;
399	delete vectP1;
400	fVert.SetXYZ(initPos);
401	fVert.SetDispersion(sigma);
402	fVert.SetNContributors(knacc);
403	}
404	//_______________________________________________________________________
405	Double_t AliVertexerTracks::GetDeterminant3X3(Double_t matr[][3]){
406	//
407	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];
408	return det;
409	}
410	//____________________________________________________________________________
411	void AliVertexerTracks::GetStrLinDerivMatrix(Double_t p0,Double_t p1,Double_t m[][3],Double_t *d){
412
413	//
414	Double_t x12=p0[0]-p1[0];
415	Double_t y12=p0[1]-p1[1];
416	Double_t z12=p0[2]-p1[2];
417	Double_t kk=x12x12+y12y12+z12*z12;
418	m[0][0]=2-2/kkx12x12;
419	m[0][1]=-2/kkx12y12;
420	m[0][2]=-2/kkx12z12;
421	m[1][0]=-2/kkx12y12;
422	m[1][1]=2-2/kky12y12;
423	m[1][2]=-2/kky12z12;
424	m[2][0]=-2/kkx12z12;
425	m[2][1]=-2y12z12;
426	m[2][2]=2-2/kkz12z12;
427	d[0]=2p0[0]-2/kkp0[0]x12x12-2/kkp0[2]x12z12-2/kkp0[1]x12y12;
428	d[1]=2p0[1]-2/kkp0[1]y12y12-2/kkp0[0]x12y12-2/kkp0[2]z12y12;
429	d[2]=2p0[2]-2/kkp0[2]z12z12-2/kkp0[0]x12z12-2/kkp0[1]z12y12;
430
431	}
432	//____________________________________________________________________________
433	void AliVertexerTracks::GetStrLinDerivMatrix(Double_t p0,Double_t p1,Double_t sigmasq,Double_t m[][3],Double_t d){
434	//
435	Double_t x12=p1[0]-p0[0];
436	Double_t y12=p1[1]-p0[1];
437	Double_t z12=p1[2]-p0[2];
438
439	Double_t den= x12x12sigmasq[1]sigmasq[2]+y12y12sigmasq[0]sigmasq[2]+z12z12sigmasq[0]*sigmasq[1];
440
441	Double_t kk= 2(x12x12/sigmasq[0]+y12y12/sigmasq[1]+z12z12/sigmasq[2]);
442
443	Double_t cc[3];
444	cc[0]=-x12/sigmasq[0];
445	cc[1]=-y12/sigmasq[1];
446	cc[2]=-z12/sigmasq[2];
447
448	Double_t ww=(-p0[0]x12sigmasq[1]sigmasq[2]-p0[1]y12sigmasq[0]sigmasq[2]-p0[2]z12sigmasq[0]*sigmasq[1])/den;
449
450	Double_t ss= -p0[0]cc[0]-p0[1]cc[1]-p0[2]*cc[2];
451
452	Double_t aa[3];
453	aa[0]=x12sigmasq[1]sigmasq[2]/den;
454	aa[1]=y12sigmasq[0]sigmasq[2]/den;
455	aa[2]=z12sigmasq[0]sigmasq[1]/den;
456
457	m[0][0]=aa[0](aa[0]kk+2cc[0])+2cc[0]*aa[0]+2/sigmasq[0];
458	m[0][1]=aa[1](aa[0]kk+2cc[0])+2cc[1]*aa[0];
459	m[0][2]=aa[2](aa[0]kk+2cc[0])+2cc[2]*aa[0];
460
461	m[1][0]=aa[0](aa[1]kk+2cc[1])+2cc[0]*aa[1];
462	m[1][1]=aa[1](aa[1]kk+2cc[1])+2cc[1]*aa[1]+2/sigmasq[1];
463	m[1][2]=aa[2](aa[1]kk+2cc[1])+2cc[2]*aa[1];
464
465	m[2][0]=aa[0](aa[2]kk+2cc[2])+2cc[0]*aa[2];
466	m[2][1]=aa[1](aa[2]kk+2cc[2])+2cc[1]*aa[2];
467	m[2][2]=aa[2](aa[2]kk+2cc[2])+2cc[2]*aa[2]+2/sigmasq[2];
468
469	d[0]=-ww(aa[0]kk+2cc[0])-2ssaa[0]+2p0[0]/sigmasq[0];
470	d[1]=-ww(aa[1]kk+2cc[1])-2ssaa[1]+2p0[1]/sigmasq[1];
471	d[2]=-ww(aa[2]kk+2cc[2])-2ssaa[2]+2p0[2]/sigmasq[2];
472
473	}
474	//_____________________________________________________________________________
475	Double_t AliVertexerTracks::GetStrLinMinDist(Double_t p0,Double_t p1,Double_t *x0){
476	//
477	Double_t x12=p0[0]-p1[0];
478	Double_t y12=p0[1]-p1[1];
479	Double_t z12=p0[2]-p1[2];
480	Double_t x10=p0[0]-x0[0];
481	Double_t y10=p0[1]-x0[1];
482	Double_t z10=p0[2]-x0[2];
483	return ((x10x10+y10y10+z10z10)(x12x12+y12y12+z12z12)-(x10x12+y10y12+z10z12)(x10x12+y10y12+z10z12))/(x12x12+y12y12+z12*z12);
484	}