[u/mrichter/AliRoot.git] / HLT / src / AliL3Fitter.cxx

// @(#) $Id$

// Author: Anders Vestbo <mailto:vestbo@fi.uib.no>
//*-- Copyright &copy ALICE HLT Group 

/** \class AliL3Fitter
<pre>
//_____________________________________________________________
// AliL3Fitter
//
// Fit class HLT for helix
</pre>
*/

#include <math.h>
#include "AliL3StandardIncludes.h"
#include "AliL3Logging.h"
#include "AliL3Fitter.h"
#include "AliL3Vertex.h"
#include "AliL3Track.h"
#include "AliL3SpacePointData.h"
#include "AliL3MemHandler.h"
#include "AliL3Transform.h"
#include "AliLevel3.h"


ClassImp(AliL3Fitter)


AliL3Fitter::AliL3Fitter()
{
  //constructor
  fTrack=0;
  fVertex=0;
  memset(fClusters,0,36*6*sizeof(AliL3SpacePointData*));
}

AliL3Fitter::AliL3Fitter(AliL3Vertex *vertex,Bool_t vertexconstraint)
{
  //constructor
  fTrack=0;
  fVertex = vertex;
  fVertexConstraint=vertexconstraint;
  memset(fClusters,0,36*6*sizeof(AliL3SpacePointData*));
}

AliL3Fitter::~AliL3Fitter()
{
  //destructor
  for(Int_t i=0; i<36; i++)
    {
      for(Int_t j=0; j<6; j++)
	{
	  if(fClusters[i][j])
	    delete [] fClusters[i][j];
	}
    }
}

void AliL3Fitter::LoadClusters(Char_t *path,Int_t event,Bool_t sp)
{
  //load clusters
  Char_t fname[256];
  AliL3MemHandler *clusterfile[36][6];
  for(Int_t s=0; s<=35; s++)
    {
      for(Int_t p=0; p<6; p++)
	{
	  Int_t patch;
	  if(sp==kTRUE)
	    patch=-1;
	  else
	    patch=p;
	  if(fClusters[s][p])
	    delete fClusters[s][p];
	  fClusters[s][p] = 0;
	  clusterfile[s][p] = new AliL3MemHandler();
	  sprintf(fname,"%s/points_%d_%d_%d.raw",path,event,s,patch);
	  if(!clusterfile[s][p]->SetBinaryInput(fname))
	    {
	      delete clusterfile[s][p];
              clusterfile[s][p] = 0; 
	      continue;
	    }
	  fClusters[s][p] = (AliL3SpacePointData*)clusterfile[s][p]->Allocate();
	  clusterfile[s][p]->Binary2Memory(fNcl[s][p],fClusters[s][p]);
	  clusterfile[s][p]->CloseBinaryInput();
	  if(sp==kTRUE)
	    break;
	}
    }
}

void AliL3Fitter::SortTrackClusters(AliL3Track *track) const
{
  //Sort the internal cluster list in each track with respect to row numbering.
  //This may be necessary when no conventional track follower has been
  //applied, in which the cluster list has been maintained in a more
  //arbitrary fashion.

  Int_t nhits = track->GetNHits();
  Int_t *ids = (Int_t*)track->GetHitNumbers();
  Int_t *origids = new Int_t[nhits];
  Int_t *mk = new Int_t[nhits];
  Int_t k;

  for(k=0; k<nhits; k++) {origids[k] = ids[k]; mk[k] = -1;}
  
  Int_t slice,patch,id,padrow,maxrow,maxk;
  UInt_t pos;
  for(Int_t j=0; j<nhits; j++)
    {
      maxrow=-1;
      maxk=200;
      for(k=0; k<nhits; k++)
	{
	  id=ids[k];
	  if(id < 0) continue;
	  slice = (id>>25) & 0x7f;
	  patch = (id>>22) & 0x7;
	  pos = id&0x3fffff;	      
	  AliL3SpacePointData *points = fClusters[slice][patch];
	  padrow = points[pos].fPadRow;
	  if(padrow > maxrow)
	    {
	      maxrow = padrow;
	      maxk=k;
	    }
	}
      mk[j]=maxk;
      ids[maxk]=-1;
    }
    
  for(k=0; k<nhits; k++)
    ids[k] = origids[mk[k]];
  delete [] origids;
  delete [] mk;
}

Int_t AliL3Fitter::FitHelix(AliL3Track *track)
{
  //fit helix parameters
  fTrack = track;
  if(FitCircle())
    {
      LOG(AliL3Log::kError,"AliL3Fitter::FitHelix","TrackFit")<<AliL3Log::kDec<<
	"Problems during circle fit"<<ENDLOG;
      return 1;
    }
  if(FitLine())
    {
      LOG(AliL3Log::kError,"AliL3Fitter::FitHelix","TrackFit")<<AliL3Log::kDec<<
	"Problems during line fit"<<ENDLOG;
      return 1;
    }
  return 0;
}

Int_t AliL3Fitter::FitCircle()
{
  //-----------------------------------------------------------------
  //Fits circle parameters using algorithm
  //described by ChErnov and Oskov in Computer Physics
  //Communications.
  // 
  //Written in FORTRAN by Jawluen Tang, Physics department , UT-Austin 
  //Moved to C by Pablo Yepes
  //Moved to AliROOT by ASV.
  //------------------------------------------------------------------
  
  Double_t wsum  = 0.0 ;
  Double_t xav   = 0.0 ;
  Double_t yav   = 0.0 ;
  
  //
  //     Loop over hits calculating average
  Double_t * fXYWeight = new Double_t[(fTrack->GetNHits())];
  UInt_t *hitnum = fTrack->GetHitNumbers();
  for(Int_t i=0; i<fTrack->GetNHits(); i++)
    {
      UInt_t id = hitnum[i];
      Int_t slice = (id>>25) & 0x7f;
      Int_t patch = (id>>22) & 0x7;
      UInt_t pos = id&0x3fffff;
      AliL3SpacePointData *points = fClusters[slice][patch];
      fXYWeight[i] = 1./ (Double_t)(points[pos].fSigmaY2 + points[pos].fSigmaY2);
      wsum += fXYWeight[i];
      xav += fXYWeight[i]*points[pos].fX;
      yav += fXYWeight[i]*points[pos].fY;
    }
  if (fVertexConstraint == kTRUE)
    {    
      wsum += fVertex->GetXYWeight() ;
      xav  += fVertex->GetX() ;
      yav  += fVertex->GetY() ;
    }
  
  xav = xav / wsum ;
  yav = yav / wsum ;
//
//  CALCULATE <X**2>, <XY>, AND <Y**2> WITH <X> = 0, & <Y> = 0
//
  Double_t xxav  = 0.0 ;
  Double_t xyav  = 0.0 ; 
  Double_t yyav  = 0.0 ;
  Double_t xi, yi ;
  
  for(Int_t i=0; i<fTrack->GetNHits(); i++)
    { 
      UInt_t id = hitnum[i];
      Int_t slice = (id>>25) & 0x7f;
      Int_t patch = (id>>22) & 0x7;
      UInt_t pos = id&0x3fffff;
      AliL3SpacePointData *points = fClusters[slice][patch];

      xi = points[pos].fX -xav;
      yi        = points[pos].fY - yav ;
      xxav     += xi * xi * fXYWeight[i];
      xyav     += xi * yi * fXYWeight[i];
      yyav     += yi * yi * fXYWeight[i];
    }
  
  if (fVertexConstraint == kTRUE)
    {
      xi        = fVertex->GetX() - xav ;
      yi        = fVertex->GetY() - yav ;
      xxav     += xi * xi * fVertex->GetXYWeight() ;
      xyav     += xi * yi * fVertex->GetXYWeight() ;
      yyav     += yi * yi * fVertex->GetXYWeight() ; 
    }
  xxav = xxav / wsum ;
  xyav = xyav / wsum ;
  yyav = yyav / wsum ;
//
//-->  ROTATE COORDINATES SO THAT <XY> = 0
//
//-->  SIGN(C**2 - S**2) = SIGN(XXAV - YYAV) >
//-->  &                                     > ==> NEW : (XXAV-YYAV) > 0
//-->  SIGN(S) = SIGN(XYAV)                  >

  Double_t a = fabs( xxav - yyav ) ;
  Double_t b = 4.0 * xyav * xyav ;

  Double_t asqpb  = a * a + b  ;
  Double_t rasqpb = sqrt ( asqpb) ;

  Double_t splus  = 1.0 + a / rasqpb ;
  Double_t sminus = b / (asqpb * splus) ;

  splus  = sqrt (0.5 * splus ) ;
  sminus = sqrt (0.5 * sminus) ;
//
//->  FIRST REQUIRE : SIGN(C**2 - S**2) = SIGN(XXAV - YYAV)
//
  Double_t sinrot, cosrot ;
  if ( xxav <= yyav ) {
	 cosrot = sminus ;
	 sinrot = splus  ;
  }
  else {
	  cosrot = splus ;
	  sinrot = sminus ;
  }
//
//->  REQUIRE : SIGN(S) = SIGN(XYAV) * SIGN(C) (ASSUMING SIGN(C) > 0)
//
  if ( xyav < 0.0 ) sinrot = - sinrot ;
//
//-->  WE NOW HAVE THE SMALLEST ANGLE THAT GUARANTEES <X**2> > <Y**2>
//-->  TO GET THE SIGN OF THE CHARGE RIGHT, THE NEW X-AXIS MUST POINT
//-->  OUTWARD FROM THE ORGIN.  WE ARE FREE TO CHANGE SIGNS OF BOTH
//-->  COSROT AND SINROT SIMULTANEOUSLY TO ACCOMPLISH THIS.
//
//-->  CHOOSE SIGN OF C WISELY TO BE ABLE TO GET THE SIGN OF THE CHARGE
//
  if ( cosrot*xav+sinrot*yav < 0.0 ) {
	  cosrot = -cosrot ;
	  sinrot = -sinrot ;
  }
//
//->  NOW GET <R**2> AND RSCALE= SQRT(<R**2>)
//
  Double_t rrav   = xxav + yyav ;
  Double_t rscale = sqrt(rrav) ;

  xxav   = 0.0 ;
  yyav   = 0.0 ;
  xyav   = 0.0 ;
  Double_t xrrav = 0.0 ;
  Double_t yrrav = 0.0 ;
  Double_t rrrrav  = 0.0 ;

  Double_t xixi, yiyi, riri, wiriri, xold, yold ;
  
  for(Int_t i=0; i<fTrack->GetNHits(); i++)
    { 
      UInt_t id = hitnum[i];
      Int_t slice = (id>>25) & 0x7f;
      Int_t patch = (id>>22) & 0x7;
      UInt_t pos = id&0x3fffff;
      AliL3SpacePointData *points = fClusters[slice][patch];
      
      xold = points[pos].fX - xav ;
      yold = points[pos].fY - yav ;
      //
      //-->  ROTATE SO THAT <XY> = 0 & DIVIDE BY RSCALE SO THAT <R**2> = 1
      //
      xi = (  cosrot * xold + sinrot * yold ) / rscale ;
      yi = ( -sinrot * xold + cosrot * yold ) / rscale ;
      
      xixi   = xi * xi ;
      yiyi   = yi * yi ;
      riri   = xixi + yiyi ;
      wiriri = fXYWeight[i] * riri ;
      
      xyav   += fXYWeight[i] * xi * yi ;
      xxav   += fXYWeight[i] * xixi ;
      yyav   += fXYWeight[i] * yiyi ;
      
      xrrav  += wiriri * xi ;
      yrrav  += wiriri * yi ;
      rrrrav += wiriri * riri ;
    }
//
//   Include vertex if required
//
  if (fVertexConstraint == kTRUE)
    {
      xold = fVertex->GetX() - xav ;
	yold = fVertex->GetY() - yav ;
	//
	//-->  ROTATE SO THAT <XY> = 0 & DIVIDE BY RSCALE SO THAT <R**2> = 1
	//
	xi = (  cosrot * xold + sinrot * yold ) / rscale ;
	yi = ( -sinrot * xold + cosrot * yold ) / rscale ;
	
	xixi   = xi * xi ;
	yiyi   = yi * yi ;
	riri   = xixi + yiyi ;
	wiriri = fVertex->GetXYWeight() * riri ;

	xyav   += fVertex->GetXYWeight() * xi * yi ;
	xxav   += fVertex->GetXYWeight() * xixi ;
	yyav   += fVertex->GetXYWeight() * yiyi ;

	xrrav  += wiriri * xi ;
	yrrav  += wiriri * yi ;
	rrrrav += wiriri * riri ;
  }
  //
  //    
  //
  //-->  DIVIDE BY WSUM TO MAKE AVERAGES
  //
  xxav    = xxav   / wsum ;
  yyav    = yyav   / wsum ;
  xrrav   = xrrav  / wsum ;
  yrrav   = yrrav  / wsum ;
  rrrrav  = rrrrav / wsum ;
  xyav    = xyav   / wsum ;

  Int_t const kntry = 5 ;
//
//-->  USE THESE TO GET THE COEFFICIENTS OF THE 4-TH ORDER POLYNIMIAL
//-->  DON'T PANIC - THE THIRD ORDER TERM IS ZERO !
//
  Double_t xrrxrr = xrrav * xrrav ;
  Double_t yrryrr = yrrav * yrrav ;
  Double_t rrrrm1 = rrrrav - 1.0  ;
  Double_t xxyy   = xxav  * yyav  ;        

  Double_t c0  =          rrrrm1*xxyy - xrrxrr*yyav - yrryrr*xxav ;
  Double_t c1  =        - rrrrm1      + xrrxrr      + yrryrr   - 4.0*xxyy ;        
  Double_t c2  =   4.0  + rrrrm1                               - 4.0*xxyy ;           
  Double_t c4  = - 4.0  ;                
//
//-->  COEFFICIENTS OF THE DERIVATIVE - USED IN NEWTON-RAPHSON ITERATIONS
//
  Double_t c2d =   2.0 * c2 ;
  Double_t c4d =   4.0 * c4 ;
//
//-->  0'TH VALUE OF LAMDA - LINEAR INTERPOLATION BETWEEN P(0) & P(YYAV)
//
//   LAMDA = YYAV * C0 / (C0 + YRRSQ * (XXAV-YYAV))
  Double_t lamda  = 0.0 ;
  Double_t dlamda = 0.0 ;
//
  Double_t chiscl = wsum * rscale * rscale ;
  Double_t dlamax = 0.001 / chiscl ;   
   
  Double_t p, pd ;
  for ( int itry = 1 ; itry <= kntry ; itry++ ) {
     p      = c0 + lamda * (c1 + lamda * (c2 + lamda * lamda * c4 )) ;
     pd     = (c1 + lamda * (c2d + lamda * lamda * c4d)) ;
     dlamda = -p / pd ;
     lamda  = lamda + dlamda ;
     if (fabs(dlamda)<   dlamax) break ;
  }

  //Double_t chi2 = (Double_t)(chiscl * lamda) ;
  //fTrack->SetChiSq1(chi2);
  // Double_t dchisq = chiscl * dlamda ;	     
  //
  //-->  NOW CALCULATE THE MATRIX ELEMENTS FOR ALPHA, BETA & KAPPA
  //
  Double_t h11   = xxav  -     lamda ;
  Double_t h14   = xrrav ;
  Double_t h22   = yyav  -     lamda ; 
  Double_t h24   = yrrav ;
  Double_t h34   = 1.0   + 2.0*lamda ;
  if ( h11 == 0.0 || h22 == 0.0 ){
    LOG(AliL3Log::kError,"AliL3Fitter::FitCircle","TrackFit")<<AliL3Log::kDec<<
      "Problems fitting circle"<<ENDLOG;
    return 1 ;
  }
  Double_t rootsq = (h14*h14)/(h11*h11) + 4.0*h34 ;

  Double_t ratio, kappa, beta ;
  if ( fabs(h22) > fabs(h24) ) {
     ratio  = h24 / h22 ;
     rootsq = ratio * ratio + rootsq ;
     kappa = 1.0 / sqrt(rootsq) ;
     beta  = - ratio * kappa ;
  }
  else {
     ratio  = h22 / h24 ;
     rootsq = 1.0 + ratio * ratio * rootsq ;
     beta  = 1.0 / sqrt(rootsq) ;
     if ( h24 > 0 ) beta = - beta ;
     kappa = -ratio * beta ;
  }            
  Double_t alpha = - (h14/h11) * kappa ;
//
//-->  transform these into the lab coordinate system
//-->  first get kappa and back to real dimensions
//
  Double_t kappa1 = kappa / rscale ;
  Double_t dbro   = 0.5   / kappa1 ;
//
//-->  next rotate alpha and beta and scale
//
  Double_t alphar = (cosrot * alpha - sinrot * beta)* dbro ;
  Double_t betar  = (sinrot * alpha + cosrot * beta)* dbro ;
//
//-->  then translate by (xav,yav)
//
  Double_t acent  = (double)(xav - alphar) ;
  Double_t bcent  = (double)(yav - betar ) ;
  Double_t radius = (double)dbro ;
//
//   Get charge
//
  Int_t q = ( ( yrrav < 0 ) ? 1 : -1 ) ;
  fTrack->SetCharge(q);
  
  //Set the first point on the track to the space point coordinates of the innermost track
  //This will be updated to lie on the fit later on (AliL3Track::UpdateToFirstPoint).
  Double_t x0,y0,psi,pt ;
  Int_t lastid=fTrack->GetNHits()-1;
  UInt_t id = hitnum[lastid];
  Int_t slice = (id>>25) & 0x7f;
  Int_t patch = (id>>22) & 0x7;
  UInt_t pos = id&0x3fffff;
  AliL3SpacePointData *points = fClusters[slice][patch];
  x0   =  points[pos].fX;
  y0   =  points[pos].fY;
  fTrack->SetFirstPoint(x0,y0,0); //Z-value is set in FitLine
  
  //Set the remaining fit parameters
  psi  = (Double_t)atan2(bcent-y0,acent-x0) ;
  psi  = psi + q * 0.5F * AliL3Transform::Pi() ;
  if ( psi < 0 ) psi = psi + 2*AliL3Transform::Pi();
  
  pt   = (Double_t)(AliL3Transform::GetBFact() * AliL3Transform::GetBField() * radius ) ;
  fTrack->SetPsi(psi);
  fTrack->SetPt(pt);
  fTrack->SetRadius(radius);
  fTrack->SetCenterX(acent);
  fTrack->SetCenterY(bcent);
//
//    Get errors from fast fit
//
  //if ( getPara()->getErrors ) getErrorsCircleFit ( acent, bcent, radius ) ;
//
  delete [] fXYWeight;
  return 0 ;
}

//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
//    Fit Line in s-z plane
//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Int_t AliL3Fitter::FitLine ( )
{
  //
  //Initialization 
  //
  Double_t sum = 0.F ;
  Double_t ss  = 0.F ;
  Double_t sz  = 0.F ;
  Double_t sss = 0.F ;
  Double_t ssz = 0.F ;
  //
  //find sum , sums ,sumz, sumss 
  // 
  Double_t dx, dy ;
  Double_t radius = (Double_t)(fTrack->GetPt() / ( AliL3Transform::GetBFact() * AliL3Transform::GetBField() ) ) ;

  Double_t * fS = new Double_t[(fTrack->GetNHits())];
  Double_t *fZWeight = new Double_t[fTrack->GetNHits()];
  UInt_t *hitnum = fTrack->GetHitNumbers();
  if (0)//fVertexConstraint==kTRUE)
    {
      UInt_t id = hitnum[0];
      Int_t slice = (id>>25) & 0x7f;
      Int_t patch = (id>>22) & 0x7;
      UInt_t pos = id&0x3fffff;
      AliL3SpacePointData *points = fClusters[slice][patch];
      
      dx = points[pos].fX - fVertex->GetX();
      dy = points[pos].fY - fVertex->GetY();
    }
  else 
    {
      UInt_t id = hitnum[0];
      Int_t slice = (id>>25) & 0x7f;
      Int_t patch = (id>>22) & 0x7;
      UInt_t posf = id&0x3fffff;
      AliL3SpacePointData *pointsf = fClusters[slice][patch];
      id = hitnum[(fTrack->GetNHits()-1)];
      slice = (id>>25) & 0x7f;
      patch = (id>>22) & 0x7;
      UInt_t posl = id&0x3fffff;
      AliL3SpacePointData *pointsl = fClusters[slice][patch];
      dx = pointsf[posf].fX - pointsl[posl].fX;
      dy = pointsf[posf].fY - pointsl[posl].fY;
    }

  Double_t localPsi = 0.5F * sqrt ( dx*dx + dy*dy ) / radius ;
  Double_t totals ;
  
  if ( fabs(localPsi) < 1. ) 
    {
      totals = 2.0 * radius * asin ( localPsi ) ;
    } 
  else 
    { 
      totals = 2.0 * radius * AliL3Transform::Pi() ;
    } 
  
  Double_t dpsi,s;
  
  for(Int_t i=0; i<fTrack->GetNHits(); i++)
    { 
      UInt_t id = hitnum[i];
      Int_t slice = (id>>25) & 0x7f;
      Int_t patch = (id>>22) & 0x7;
      UInt_t pos = id&0x3fffff;
      AliL3SpacePointData *points = fClusters[slice][patch];
      
      fZWeight[i] = 1./(Double_t)(points[pos].fSigmaZ2);
      if(i>0)
	{
	  id = hitnum[i-1];
	  slice = (id>>25) & 0x7f;
	  patch = (id>>22) & 0x7;
	  UInt_t lastpos = id&0x3fffff;
	  AliL3SpacePointData *lastpoints = fClusters[slice][patch];
	  dx = points[pos].fX -lastpoints[lastpos].fX;
	  dy = points[pos].fY -lastpoints[lastpos].fY;
	  dpsi = 0.5 * (Double_t)sqrt ( dx*dx + dy*dy ) / radius ;
	  if(fabs(dpsi) > 1)
	    return 1;
	  fTrack->SetPsierr(dpsi);
	  s = fS[i-1] - 2.0 * radius * (Double_t)asin ( dpsi ) ;
	  fS[i]=s;
	}
      else
	fS[i]=totals;
      
      sum += fZWeight[i];
      ss  += fZWeight[i] * fS[i];
      sz  += fZWeight[i] * points[pos].fZ;
      sss += fZWeight[i] * fS[i] * fS[i];
      ssz += fZWeight[i] * fS[i] * points[pos].fZ;
      
    }
  
  
  Double_t chi2,det = sum * sss - ss * ss;
  if ( fabs(det) < 1e-20)
    { 
      chi2 = 99999.F ;
      //fTrack->SetChiSq2(chi2);
      return 0 ;
    }
  
  //Compute the best fitted parameters A,B
  Double_t tanl,z0,dtanl,dz0;

  tanl = (Double_t)((sum * ssz - ss * sz ) / det );
  z0   = (Double_t)((sz * sss - ssz * ss ) / det );

  fTrack->SetTgl(tanl);
  fTrack->SetZ0(z0);
  
  //calculate chi-square 
  chi2 = 0.;
  Double_t r1 ;
  
  for(Int_t i=0; i<fTrack->GetNHits(); i++)
    { 
      UInt_t id = hitnum[i];
      Int_t slice = (id>>25) & 0x7f;
      Int_t patch = (id>>22) & 0x7;
      UInt_t pos = id&0x3fffff;
      AliL3SpacePointData *points = fClusters[slice][patch];
      r1   = points[pos].fZ - tanl * fS[i] - z0 ;
      chi2 += (Double_t) ( (Double_t)(fZWeight[i]) * (r1 * r1) );
    }
  
  //fTrack->SetChiSq2(chi2);
  //
  //calculate estimated variance
  //varsq=chi/(double(n)-2.) 
  //calculate covariance matrix 
  //siga=sqrt(varsq*sxx/det) 
  //sigb=sqrt(varsq*sum/det) 
  //
  dtanl = (Double_t) ( sum / det );
  dz0   = (Double_t) ( sss / det );
  
  fTrack->SetTglerr(dtanl);
  fTrack->SetZ0err(dz0);
  delete [] fZWeight;
  delete [] fS;
  return 0 ;
}
Commit	Line	Data
3e87ef69	1	// @(#) $Id$
1934a2f8	2
1934a2f8	3	// Author: Anders Vestbo <mailto:vestbo@fi.uib.no>
3e87ef69	4	//*-- Copyright &copy ALICE HLT Group
1934a2f8	5
159a9e4e	6	/** \class AliL3Fitter
	7	<pre>
	8	//_____________________________________________________________
	9	// AliL3Fitter
	10	//
	11	// Fit class HLT for helix
	12	</pre>
	13	*/
	14
1934a2f8	15	#include <math.h>
e9ecfae3	16	#include "AliL3StandardIncludes.h"
1934a2f8	17	#include "AliL3Logging.h"
	18	#include "AliL3Fitter.h"
	19	#include "AliL3Vertex.h"
	20	#include "AliL3Track.h"
	21	#include "AliL3SpacePointData.h"
355debe1	22	#include "AliL3MemHandler.h"
02ddf7f2	23	#include "AliL3Transform.h"
6f388e0d	24	#include "AliLevel3.h"
3e87ef69	25
1934a2f8	26
	27	ClassImp(AliL3Fitter)
	28
0a86fbb7	29
	30	AliL3Fitter::AliL3Fitter()
	31	{
159a9e4e	32	//constructor
0a86fbb7	33	fTrack=0;
	34	fVertex=0;
	35	memset(fClusters,0,366sizeof(AliL3SpacePointData*));
	36	}
	37
	38	AliL3Fitter::AliL3Fitter(AliL3Vertex *vertex,Bool_t vertexconstraint)
1934a2f8	39	{
	40	//constructor
	41	fTrack=0;
	42	fVertex = vertex;
0a86fbb7	43	fVertexConstraint=vertexconstraint;
3e87ef69	44	memset(fClusters,0,366sizeof(AliL3SpacePointData*));
1934a2f8	45	}
1934a2f8	46
3e87ef69	47	AliL3Fitter::~AliL3Fitter()
3e87ef69	48	{
159a9e4e	49	//destructor
3e87ef69	50	for(Int_t i=0; i<36; i++)
	51	{
	52	for(Int_t j=0; j<6; j++)
	53	{
	54	if(fClusters[i][j])
a62ccff4	55	delete [] fClusters[i][j];
3e87ef69	56	}
	57	}
	58	}
	59
	60	void AliL3Fitter::LoadClusters(Char_t *path,Int_t event,Bool_t sp)
1934a2f8	61	{
159a9e4e	62	//load clusters
1934a2f8	63	Char_t fname[256];
355debe1	64	AliL3MemHandler *clusterfile[36][6];
1934a2f8	65	for(Int_t s=0; s<=35; s++)
	66	{
	67	for(Int_t p=0; p<6; p++)
	68	{
3e87ef69	69	Int_t patch;
	70	if(sp==kTRUE)
	71	patch=-1;
	72	else
	73	patch=p;
	74	if(fClusters[s][p])
	75	delete fClusters[s][p];
	76	fClusters[s][p] = 0;
355debe1	77	clusterfile[s][p] = new AliL3MemHandler();
3e87ef69	78	sprintf(fname,"%s/points_%d_%d_%d.raw",path,event,s,patch);
1934a2f8	79	if(!clusterfile[s][p]->SetBinaryInput(fname))
	80	{
	81	delete clusterfile[s][p];
	82	clusterfile[s][p] = 0;
	83	continue;
	84	}
	85	fClusters[s][p] = (AliL3SpacePointData*)clusterfile[s][p]->Allocate();
	86	clusterfile[s][p]->Binary2Memory(fNcl[s][p],fClusters[s][p]);
	87	clusterfile[s][p]->CloseBinaryInput();
3e87ef69	88	if(sp==kTRUE)
3e87ef69	89	break;
1934a2f8	90	}
	91	}
	92	}
	93
159a9e4e	94	void AliL3Fitter::SortTrackClusters(AliL3Track *track) const
0a86fbb7	95	{
	96	//Sort the internal cluster list in each track with respect to row numbering.
	97	//This may be necessary when no conventional track follower has been
	98	//applied, in which the cluster list has been maintained in a more
	99	//arbitrary fashion.
	100
	101	Int_t nhits = track->GetNHits();
	102	Int_t ids = (Int_t)track->GetHitNumbers();
	103	Int_t *origids = new Int_t[nhits];
	104	Int_t *mk = new Int_t[nhits];
	105	Int_t k;
	106
	107	for(k=0; k<nhits; k++) {origids[k] = ids[k]; mk[k] = -1;}
	108
	109	Int_t slice,patch,id,padrow,maxrow,maxk;
	110	UInt_t pos;
	111	for(Int_t j=0; j<nhits; j++)
	112	{
	113	maxrow=-1;
	114	maxk=200;
	115	for(k=0; k<nhits; k++)
	116	{
	117	id=ids[k];
	118	if(id < 0) continue;
	119	slice = (id>>25) & 0x7f;
	120	patch = (id>>22) & 0x7;
	121	pos = id&0x3fffff;
	122	AliL3SpacePointData *points = fClusters[slice][patch];
	123	padrow = points[pos].fPadRow;
	124	if(padrow > maxrow)
	125	{
	126	maxrow = padrow;
	127	maxk=k;
	128	}
	129	}
	130	mk[j]=maxk;
	131	ids[maxk]=-1;
	132	}
	133
	134	for(k=0; k<nhits; k++)
	135	ids[k] = origids[mk[k]];
	136	delete [] origids;
	137	delete [] mk;
	138	}
	139
1934a2f8	140	Int_t AliL3Fitter::FitHelix(AliL3Track *track)
1934a2f8	141	{
159a9e4e	142	//fit helix parameters
1934a2f8	143	fTrack = track;
	144	if(FitCircle())
	145	{
	146	LOG(AliL3Log::kError,"AliL3Fitter::FitHelix","TrackFit")<<AliL3Log::kDec<<
	147	"Problems during circle fit"<<ENDLOG;
	148	return 1;
	149	}
	150	if(FitLine())
	151	{
	152	LOG(AliL3Log::kError,"AliL3Fitter::FitHelix","TrackFit")<<AliL3Log::kDec<<
	153	"Problems during line fit"<<ENDLOG;
	154	return 1;
	155	}
	156	return 0;
	157	}
	158
	159	Int_t AliL3Fitter::FitCircle()
	160	{
	161	//-----------------------------------------------------------------
	162	//Fits circle parameters using algorithm
	163	//described by ChErnov and Oskov in Computer Physics
	164	//Communications.
	165	//
	166	//Written in FORTRAN by Jawluen Tang, Physics department , UT-Austin
	167	//Moved to C by Pablo Yepes
	168	//Moved to AliROOT by ASV.
	169	//------------------------------------------------------------------
	170
	171	Double_t wsum = 0.0 ;
	172	Double_t xav = 0.0 ;
	173	Double_t yav = 0.0 ;
	174
	175	//
	176	// Loop over hits calculating average
62bb4b3d	177	Double_t * fXYWeight = new Double_t[(fTrack->GetNHits())];
1934a2f8	178	UInt_t *hitnum = fTrack->GetHitNumbers();
	179	for(Int_t i=0; i<fTrack->GetNHits(); i++)
	180	{
	181	UInt_t id = hitnum[i];
	182	Int_t slice = (id>>25) & 0x7f;
	183	Int_t patch = (id>>22) & 0x7;
	184	UInt_t pos = id&0x3fffff;
1934a2f8	185	AliL3SpacePointData *points = fClusters[slice][patch];
3e87ef69	186	fXYWeight[i] = 1./ (Double_t)(points[pos].fSigmaY2 + points[pos].fSigmaY2);
1934a2f8	187	wsum += fXYWeight[i];
	188	xav += fXYWeight[i]*points[pos].fX;
	189	yav += fXYWeight[i]*points[pos].fY;
1934a2f8	190	}
	191	if (fVertexConstraint == kTRUE)
	192	{
	193	wsum += fVertex->GetXYWeight() ;
	194	xav += fVertex->GetX() ;
	195	yav += fVertex->GetY() ;
	196	}
	197
	198	xav = xav / wsum ;
	199	yav = yav / wsum ;
	200	//
	201	// CALCULATE <X2>, <XY>, AND <Y2> WITH <X> = 0, & <Y> = 0
	202	//
	203	Double_t xxav = 0.0 ;
	204	Double_t xyav = 0.0 ;
	205	Double_t yyav = 0.0 ;
	206	Double_t xi, yi ;
3e87ef69	207
1934a2f8	208	for(Int_t i=0; i<fTrack->GetNHits(); i++)
	209	{
	210	UInt_t id = hitnum[i];
	211	Int_t slice = (id>>25) & 0x7f;
	212	Int_t patch = (id>>22) & 0x7;
	213	UInt_t pos = id&0x3fffff;
	214	AliL3SpacePointData *points = fClusters[slice][patch];
3e87ef69	215
1934a2f8	216	xi = points[pos].fX -xav;
	217	yi = points[pos].fY - yav ;
	218	xxav += xi * xi * fXYWeight[i];
	219	xyav += xi * yi * fXYWeight[i];
	220	yyav += yi * yi * fXYWeight[i];
	221	}
	222
	223	if (fVertexConstraint == kTRUE)
	224	{
	225	xi = fVertex->GetX() - xav ;
	226	yi = fVertex->GetY() - yav ;
	227	xxav += xi * xi * fVertex->GetXYWeight() ;
	228	xyav += xi * yi * fVertex->GetXYWeight() ;
	229	yyav += yi * yi * fVertex->GetXYWeight() ;
	230	}
	231	xxav = xxav / wsum ;
	232	xyav = xyav / wsum ;
	233	yyav = yyav / wsum ;
	234	//
	235	//--> ROTATE COORDINATES SO THAT <XY> = 0
	236	//
	237	//--> SIGN(C2 - S2) = SIGN(XXAV - YYAV) >
	238	//--> & > ==> NEW : (XXAV-YYAV) > 0
	239	//--> SIGN(S) = SIGN(XYAV) >
	240
	241	Double_t a = fabs( xxav - yyav ) ;
	242	Double_t b = 4.0 * xyav * xyav ;
	243
	244	Double_t asqpb = a * a + b ;
	245	Double_t rasqpb = sqrt ( asqpb) ;
	246
	247	Double_t splus = 1.0 + a / rasqpb ;
	248	Double_t sminus = b / (asqpb * splus) ;
	249
	250	splus = sqrt (0.5 * splus ) ;
	251	sminus = sqrt (0.5 * sminus) ;
	252	//
	253	//-> FIRST REQUIRE : SIGN(C2 - S2) = SIGN(XXAV - YYAV)
	254	//
	255	Double_t sinrot, cosrot ;
	256	if ( xxav <= yyav ) {
	257	cosrot = sminus ;
	258	sinrot = splus ;
	259	}
	260	else {
	261	cosrot = splus ;
	262	sinrot = sminus ;
	263	}
	264	//
	265	//-> REQUIRE : SIGN(S) = SIGN(XYAV) * SIGN(C) (ASSUMING SIGN(C) > 0)
	266	//
	267	if ( xyav < 0.0 ) sinrot = - sinrot ;
	268	//
	269	//--> WE NOW HAVE THE SMALLEST ANGLE THAT GUARANTEES <X2> > <Y2>
	270	//--> TO GET THE SIGN OF THE CHARGE RIGHT, THE NEW X-AXIS MUST POINT
	271	//--> OUTWARD FROM THE ORGIN. WE ARE FREE TO CHANGE SIGNS OF BOTH
	272	//--> COSROT AND SINROT SIMULTANEOUSLY TO ACCOMPLISH THIS.
	273	//
	274	//--> CHOOSE SIGN OF C WISELY TO BE ABLE TO GET THE SIGN OF THE CHARGE
	275	//
	276	if ( cosrotxav+sinrotyav < 0.0 ) {
	277	cosrot = -cosrot ;
	278	sinrot = -sinrot ;
	279	}
280	//
281	//-> NOW GET <R2> AND RSCALE= SQRT(<R2>)
282	//
283	Double_t rrav = xxav + yyav ;
284	Double_t rscale = sqrt(rrav) ;
285
286	xxav = 0.0 ;
287	yyav = 0.0 ;
288	xyav = 0.0 ;
289	Double_t xrrav = 0.0 ;
290	Double_t yrrav = 0.0 ;
291	Double_t rrrrav = 0.0 ;
292
293	Double_t xixi, yiyi, riri, wiriri, xold, yold ;
294
295	for(Int_t i=0; i<fTrack->GetNHits(); i++)
296	{
297	UInt_t id = hitnum[i];
298	Int_t slice = (id>>25) & 0x7f;
299	Int_t patch = (id>>22) & 0x7;
300	UInt_t pos = id&0x3fffff;
301	AliL3SpacePointData *points = fClusters[slice][patch];
302
303	xold = points[pos].fX - xav ;
304	yold = points[pos].fY - yav ;
305	//
306	//--> ROTATE SO THAT <XY> = 0 & DIVIDE BY RSCALE SO THAT <R**2> = 1
307	//
308	xi = ( cosrot * xold + sinrot * yold ) / rscale ;
309	yi = ( -sinrot * xold + cosrot * yold ) / rscale ;
310
311	xixi = xi * xi ;
312	yiyi = yi * yi ;
313	riri = xixi + yiyi ;
314	wiriri = fXYWeight[i] * riri ;
315
316	xyav += fXYWeight[i] * xi * yi ;
317	xxav += fXYWeight[i] * xixi ;
318	yyav += fXYWeight[i] * yiyi ;
319
320	xrrav += wiriri * xi ;
321	yrrav += wiriri * yi ;
322	rrrrav += wiriri * riri ;
323	}
e9ecfae3	324	//
1934a2f8	325	// Include vertex if required
	326	//
	327	if (fVertexConstraint == kTRUE)
	328	{
	329	xold = fVertex->GetX() - xav ;
	330	yold = fVertex->GetY() - yav ;
	331	//
	332	//--> ROTATE SO THAT <XY> = 0 & DIVIDE BY RSCALE SO THAT <R**2> = 1
	333	//
	334	xi = ( cosrot * xold + sinrot * yold ) / rscale ;
	335	yi = ( -sinrot * xold + cosrot * yold ) / rscale ;
	336
	337	xixi = xi * xi ;
	338	yiyi = yi * yi ;
	339	riri = xixi + yiyi ;
	340	wiriri = fVertex->GetXYWeight() * riri ;
	341
	342	xyav += fVertex->GetXYWeight() * xi * yi ;
	343	xxav += fVertex->GetXYWeight() * xixi ;
	344	yyav += fVertex->GetXYWeight() * yiyi ;
	345
	346	xrrav += wiriri * xi ;
	347	yrrav += wiriri * yi ;
	348	rrrrav += wiriri * riri ;
	349	}
	350	//
	351	//
	352	//
	353	//--> DIVIDE BY WSUM TO MAKE AVERAGES
	354	//
	355	xxav = xxav / wsum ;
	356	yyav = yyav / wsum ;
	357	xrrav = xrrav / wsum ;
	358	yrrav = yrrav / wsum ;
	359	rrrrav = rrrrav / wsum ;
	360	xyav = xyav / wsum ;
	361
159a9e4e	362	Int_t const kntry = 5 ;
1934a2f8	363	//
	364	//--> USE THESE TO GET THE COEFFICIENTS OF THE 4-TH ORDER POLYNIMIAL
	365	//--> DON'T PANIC - THE THIRD ORDER TERM IS ZERO !
	366	//
	367	Double_t xrrxrr = xrrav * xrrav ;
	368	Double_t yrryrr = yrrav * yrrav ;
	369	Double_t rrrrm1 = rrrrav - 1.0 ;
	370	Double_t xxyy = xxav * yyav ;
	371
	372	Double_t c0 = rrrrm1xxyy - xrrxrryyav - yrryrr*xxav ;
	373	Double_t c1 = - rrrrm1 + xrrxrr + yrryrr - 4.0*xxyy ;
	374	Double_t c2 = 4.0 + rrrrm1 - 4.0*xxyy ;
	375	Double_t c4 = - 4.0 ;
	376	//
	377	//--> COEFFICIENTS OF THE DERIVATIVE - USED IN NEWTON-RAPHSON ITERATIONS
	378	//
	379	Double_t c2d = 2.0 * c2 ;
	380	Double_t c4d = 4.0 * c4 ;
	381	//
	382	//--> 0'TH VALUE OF LAMDA - LINEAR INTERPOLATION BETWEEN P(0) & P(YYAV)
	383	//
	384	// LAMDA = YYAV * C0 / (C0 + YRRSQ * (XXAV-YYAV))
	385	Double_t lamda = 0.0 ;
	386	Double_t dlamda = 0.0 ;
	387	//
	388	Double_t chiscl = wsum * rscale * rscale ;
	389	Double_t dlamax = 0.001 / chiscl ;
	390
	391	Double_t p, pd ;
159a9e4e	392	for ( int itry = 1 ; itry <= kntry ; itry++ ) {
1934a2f8	393	p = c0 + lamda * (c1 + lamda * (c2 + lamda * lamda * c4 )) ;
	394	pd = (c1 + lamda * (c2d + lamda * lamda * c4d)) ;
	395	dlamda = -p / pd ;
	396	lamda = lamda + dlamda ;
	397	if (fabs(dlamda)< dlamax) break ;
	398	}
	399
3e87ef69	400	//Double_t chi2 = (Double_t)(chiscl * lamda) ;
1934a2f8	401	//fTrack->SetChiSq1(chi2);
1934a2f8	402	// Double_t dchisq = chiscl * dlamda ;
3e87ef69	403	//
	404	//--> NOW CALCULATE THE MATRIX ELEMENTS FOR ALPHA, BETA & KAPPA
	405	//
1934a2f8	406	Double_t h11 = xxav - lamda ;
	407	Double_t h14 = xrrav ;
	408	Double_t h22 = yyav - lamda ;
	409	Double_t h24 = yrrav ;
	410	Double_t h34 = 1.0 + 2.0*lamda ;
	411	if ( h11 == 0.0 \|\| h22 == 0.0 ){
	412	LOG(AliL3Log::kError,"AliL3Fitter::FitCircle","TrackFit")<<AliL3Log::kDec<<
	413	"Problems fitting circle"<<ENDLOG;
	414	return 1 ;
	415	}
	416	Double_t rootsq = (h14h14)/(h11h11) + 4.0*h34 ;
	417
	418	Double_t ratio, kappa, beta ;
	419	if ( fabs(h22) > fabs(h24) ) {
	420	ratio = h24 / h22 ;
	421	rootsq = ratio * ratio + rootsq ;
	422	kappa = 1.0 / sqrt(rootsq) ;
	423	beta = - ratio * kappa ;
	424	}
	425	else {
	426	ratio = h22 / h24 ;
	427	rootsq = 1.0 + ratio * ratio * rootsq ;
	428	beta = 1.0 / sqrt(rootsq) ;
	429	if ( h24 > 0 ) beta = - beta ;
	430	kappa = -ratio * beta ;
	431	}
	432	Double_t alpha = - (h14/h11) * kappa ;
	433	//
	434	//--> transform these into the lab coordinate system
	435	//--> first get kappa and back to real dimensions
	436	//
	437	Double_t kappa1 = kappa / rscale ;
	438	Double_t dbro = 0.5 / kappa1 ;
	439	//
	440	//--> next rotate alpha and beta and scale
	441	//
	442	Double_t alphar = (cosrot * alpha - sinrot * beta)* dbro ;
	443	Double_t betar = (sinrot * alpha + cosrot * beta)* dbro ;
	444	//
	445	//--> then translate by (xav,yav)
	446	//
	447	Double_t acent = (double)(xav - alphar) ;
	448	Double_t bcent = (double)(yav - betar ) ;
	449	Double_t radius = (double)dbro ;
	450	//
	451	// Get charge
	452	//
	453	Int_t q = ( ( yrrav < 0 ) ? 1 : -1 ) ;
1934a2f8	454	fTrack->SetCharge(q);
1934a2f8	455
1f1942b8	456	//Set the first point on the track to the space point coordinates of the innermost track
1f1942b8	457	//This will be updated to lie on the fit later on (AliL3Track::UpdateToFirstPoint).
0bd0c1ef	458	Double_t x0,y0,psi,pt ;
	459	Int_t lastid=fTrack->GetNHits()-1;
	460	UInt_t id = hitnum[lastid];
	461	Int_t slice = (id>>25) & 0x7f;
	462	Int_t patch = (id>>22) & 0x7;
	463	UInt_t pos = id&0x3fffff;
	464	AliL3SpacePointData *points = fClusters[slice][patch];
	465	x0 = points[pos].fX;
	466	y0 = points[pos].fY;
1f1942b8	467	fTrack->SetFirstPoint(x0,y0,0); //Z-value is set in FitLine
0bd0c1ef	468
0bd0c1ef	469	//Set the remaining fit parameters
1934a2f8	470	psi = (Double_t)atan2(bcent-y0,acent-x0) ;
02ddf7f2	471	psi = psi + q * 0.5F * AliL3Transform::Pi() ;
02ddf7f2	472	if ( psi < 0 ) psi = psi + 2*AliL3Transform::Pi();
1934a2f8	473
02ddf7f2	474	pt = (Double_t)(AliL3Transform::GetBFact() * AliL3Transform::GetBField() * radius ) ;
1934a2f8	475	fTrack->SetPsi(psi);
1934a2f8	476	fTrack->SetPt(pt);
1f1942b8	477	fTrack->SetRadius(radius);
	478	fTrack->SetCenterX(acent);
	479	fTrack->SetCenterY(bcent);
e9ecfae3	480	//
1934a2f8	481	// Get errors from fast fit
	482	//
	483	//if ( getPara()->getErrors ) getErrorsCircleFit ( acent, bcent, radius ) ;
	484	//
62bb4b3d	485	delete [] fXYWeight;
1934a2f8	486	return 0 ;
1934a2f8	487	}
	488
	489	//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
	490	// Fit Line in s-z plane
	491	//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
	492	Int_t AliL3Fitter::FitLine ( )
	493	{
	494	//
	495	//Initialization
	496	//
	497	Double_t sum = 0.F ;
	498	Double_t ss = 0.F ;
	499	Double_t sz = 0.F ;
	500	Double_t sss = 0.F ;
	501	Double_t ssz = 0.F ;
	502	//
	503	//find sum , sums ,sumz, sumss
	504	//
	505	Double_t dx, dy ;
02ddf7f2	506	Double_t radius = (Double_t)(fTrack->GetPt() / ( AliL3Transform::GetBFact() * AliL3Transform::GetBField() ) ) ;
1934a2f8	507
62bb4b3d	508	Double_t * fS = new Double_t[(fTrack->GetNHits())];
3e87ef69	509	Double_t *fZWeight = new Double_t[fTrack->GetNHits()];
1934a2f8	510	UInt_t *hitnum = fTrack->GetHitNumbers();
0bd0c1ef	511	if (0)//fVertexConstraint==kTRUE)
1934a2f8	512	{
	513	UInt_t id = hitnum[0];
	514	Int_t slice = (id>>25) & 0x7f;
	515	Int_t patch = (id>>22) & 0x7;
	516	UInt_t pos = id&0x3fffff;
	517	AliL3SpacePointData *points = fClusters[slice][patch];
	518
	519	dx = points[pos].fX - fVertex->GetX();
3e87ef69	520	dy = points[pos].fY - fVertex->GetY();
1934a2f8	521	}
	522	else
	523	{
	524	UInt_t id = hitnum[0];
	525	Int_t slice = (id>>25) & 0x7f;
	526	Int_t patch = (id>>22) & 0x7;
	527	UInt_t posf = id&0x3fffff;
	528	AliL3SpacePointData *pointsf = fClusters[slice][patch];
	529	id = hitnum[(fTrack->GetNHits()-1)];
	530	slice = (id>>25) & 0x7f;
	531	patch = (id>>22) & 0x7;
	532	UInt_t posl = id&0x3fffff;
	533	AliL3SpacePointData *pointsl = fClusters[slice][patch];
	534	dx = pointsf[posf].fX - pointsl[posl].fX;
	535	dy = pointsf[posf].fY - pointsl[posl].fY;
1934a2f8	536	}
0a86fbb7	537
1934a2f8	538	Double_t localPsi = 0.5F * sqrt ( dxdx + dydy ) / radius ;
159a9e4e	539	Double_t totals ;
1934a2f8	540
	541	if ( fabs(localPsi) < 1. )
	542	{
159a9e4e	543	totals = 2.0 * radius * asin ( localPsi ) ;
1934a2f8	544	}
	545	else
	546	{
159a9e4e	547	totals = 2.0 * radius * AliL3Transform::Pi() ;
1934a2f8	548	}
	549
	550	Double_t dpsi,s;
	551
	552	for(Int_t i=0; i<fTrack->GetNHits(); i++)
	553	{
	554	UInt_t id = hitnum[i];
	555	Int_t slice = (id>>25) & 0x7f;
	556	Int_t patch = (id>>22) & 0x7;
	557	UInt_t pos = id&0x3fffff;
	558	AliL3SpacePointData *points = fClusters[slice][patch];
	559
3e87ef69	560	fZWeight[i] = 1./(Double_t)(points[pos].fSigmaZ2);
1934a2f8	561	if(i>0)
	562	{
	563	id = hitnum[i-1];
	564	slice = (id>>25) & 0x7f;
	565	patch = (id>>22) & 0x7;
	566	UInt_t lastpos = id&0x3fffff;
	567	AliL3SpacePointData *lastpoints = fClusters[slice][patch];
	568	dx = points[pos].fX -lastpoints[lastpos].fX;
	569	dy = points[pos].fY -lastpoints[lastpos].fY;
	570	dpsi = 0.5 * (Double_t)sqrt ( dxdx + dydy ) / radius ;
0a86fbb7	571	if(fabs(dpsi) > 1)
0a86fbb7	572	return 1;
1934a2f8	573	fTrack->SetPsierr(dpsi);
	574	s = fS[i-1] - 2.0 * radius * (Double_t)asin ( dpsi ) ;
	575	fS[i]=s;
	576	}
	577	else
159a9e4e	578	fS[i]=totals;
1934a2f8	579
3e87ef69	580	sum += fZWeight[i];
	581	ss += fZWeight[i] * fS[i];
	582	sz += fZWeight[i] * points[pos].fZ;
	583	sss += fZWeight[i] * fS[i] * fS[i];
	584	ssz += fZWeight[i] * fS[i] * points[pos].fZ;
1934a2f8	585
	586	}
	587
	588
	589	Double_t chi2,det = sum * sss - ss * ss;
	590	if ( fabs(det) < 1e-20)
	591	{
	592	chi2 = 99999.F ;
	593	//fTrack->SetChiSq2(chi2);
	594	return 0 ;
	595	}
	596
	597	//Compute the best fitted parameters A,B
	598	Double_t tanl,z0,dtanl,dz0;
	599
	600	tanl = (Double_t)((sum * ssz - ss * sz ) / det );
	601	z0 = (Double_t)((sz * sss - ssz * ss ) / det );
	602
	603	fTrack->SetTgl(tanl);
	604	fTrack->SetZ0(z0);
	605
e9ecfae3	606	//calculate chi-square
1934a2f8	607	chi2 = 0.;
	608	Double_t r1 ;
	609
	610	for(Int_t i=0; i<fTrack->GetNHits(); i++)
	611	{
	612	UInt_t id = hitnum[i];
	613	Int_t slice = (id>>25) & 0x7f;
	614	Int_t patch = (id>>22) & 0x7;
	615	UInt_t pos = id&0x3fffff;
	616	AliL3SpacePointData *points = fClusters[slice][patch];
	617	r1 = points[pos].fZ - tanl * fS[i] - z0 ;
3e87ef69	618	chi2 += (Double_t) ( (Double_t)(fZWeight[i]) * (r1 * r1) );
1934a2f8	619	}
	620
	621	//fTrack->SetChiSq2(chi2);
	622	//
e9ecfae3	623	//calculate estimated variance
	624	//varsq=chi/(double(n)-2.)
	625	//calculate covariance matrix
	626	//siga=sqrt(varsq*sxx/det)
	627	//sigb=sqrt(varsq*sum/det)
1934a2f8	628	//
	629	dtanl = (Double_t) ( sum / det );
	630	dz0 = (Double_t) ( sss / det );
	631
	632	fTrack->SetTglerr(dtanl);
	633	fTrack->SetZ0err(dz0);
3e87ef69	634	delete [] fZWeight;
62bb4b3d	635	delete [] fS;
1934a2f8	636	return 0 ;
1934a2f8	637	}