[u/mrichter/AliRoot.git] / HLT / src / AliL3ConfMapFit.cxx

// @(#) $Id$

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

#include "AliL3StandardIncludes.h"

#include "AliL3Logging.h"
#include "AliL3ConfMapFit.h"
#include "AliL3Vertex.h"
#include "AliL3ConfMapTrack.h"
#include "AliL3ConfMapPoint.h"
#include "AliL3Transform.h"

/** \class AliL3ConfMapFit
<pre>
//_____________________________________________________________
// AliL3ConfMapFit
//
// Fit class for conformal mapping tracking
</pre>
*/

ClassImp(AliL3ConfMapFit)

Double_t AliL3ConfMapFit::pi=3.14159265358979323846;

AliL3ConfMapFit::AliL3ConfMapFit(AliL3ConfMapTrack *track,AliL3Vertex *vertex)
{
  //constructor
  fTrack = track;
  fVertex = vertex;
  BFACT = 0.0029980;
  
}

Int_t AliL3ConfMapFit::FitHelix()
{
  if(FitCircle())
    {
      LOG(AliL3Log::kError,"AliL3ConfMapFit::FitHelix","TrackFit")<<AliL3Log::kDec<<
	"Problems during circle fit"<<ENDLOG;
      return 1;
    }
  if(FitLine())
    {
      LOG(AliL3Log::kError,"AliL3ConfMapFit::FitHelix","TrackFit")<<AliL3Log::kDec<<
	"Problems during line fit"<<ENDLOG;
      return 1;
    }
  return 0;
}

Int_t AliL3ConfMapFit::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 ;
  
  Int_t num_of_hits = fTrack->GetNumberOfPoints();
  //
  //     Loop over hits calculating average
  Int_t co=0;
  
  for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
    {
      co++;
      AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)fTrack->currentHit;
      cHit->SetXYWeight( 1./ (Double_t)(cHit->GetXerr()*cHit->GetXerr() + cHit->GetYerr()*cHit->GetYerr()) );
      wsum      += cHit->GetXYWeight() ;
      xav       += cHit->GetXYWeight() * cHit->GetX() ;
      yav       += cHit->GetXYWeight() * cHit->GetY() ;
    }
  if(co!=num_of_hits) 
    LOG(AliL3Log::kError,"AliL3ConfMapFit::FitCircle","TrackFit")<<AliL3Log::kDec<<
      "Mismatch of hits. Counter: "<<co<<" nHits: "<<num_of_hits<<ENDLOG;
  if (fTrack->ComesFromMainVertex() == true)
    {    
      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(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
    { 
      //AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint *)hits->At(hit_counter);
      AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)fTrack->currentHit;
      xi        = cHit->GetX() - xav ;
      yi        = cHit->GetY() - yav ;
      xxav     += xi * xi * cHit->GetXYWeight() ;
      xyav     += xi * yi * cHit->GetXYWeight() ;
      yyav     += yi * yi * cHit->GetXYWeight() ;
    }
  
  if (fTrack->ComesFromMainVertex() == true)
    {
      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 (hit_counter=0; hit_counter<num_of_hits; hit_counter++) 
  for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())  
    { 
      //AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)hits->At(hit_counter);  
      AliL3ConfMapPoint* cHit = (AliL3ConfMapPoint*)fTrack->currentHit;

      xold = cHit->GetX() - xav ;
      yold = cHit->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 = cHit->GetXYWeight() * riri ;
      
      xyav   += cHit->GetXYWeight() * xi * yi ;
      xxav   += cHit->GetXYWeight() * xixi ;
      yyav   += cHit->GetXYWeight() * yiyi ;
      
      xrrav  += wiriri * xi ;
      yrrav  += wiriri * yi ;
      rrrrav += wiriri * riri ;
    }
  //
//   Include vertex if required
//
  if (fTrack->ComesFromMainVertex() == true)
    {
	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 ntry = 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 <= ntry ; 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,"AliL3ConfMapFit::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);
  
//
//    Get other track parameters
//
  Double_t x0, y0,phi0,r0,psi,pt ;
  if ( fTrack->ComesFromMainVertex() == true ) 
    {
      //flag = 1 ; // primary track flag
      x0   = fVertex->GetX() ;
      y0   = fVertex->GetY() ;
      phi0 = fVertex->GetPhi() ;
      r0   = fVertex->GetR() ;
      fTrack->SetPhi0(phi0);
      fTrack->SetR0(r0);
    } 
  else 
    {
      //AliL3ConfMapPoint *lHit = (AliL3ConfMapPoint*)hits->Last();
      AliL3ConfMapPoint *lHit = (AliL3ConfMapPoint*)fTrack->lastHit;
      //flag =  0 ; // primary track flag
      x0   =  lHit->GetX()  ;
      y0   =  lHit->GetY()  ;
      phi0 =  atan2(lHit->GetY(),lHit->GetX());
      if ( phi0 < 0 ) phi0 += 2*pi;
      r0   =  sqrt ( lHit->GetX() * lHit->GetX() + lHit->GetY() * lHit->GetY() )  ;
      fTrack->SetPhi0(phi0);
      fTrack->SetR0(r0);

    }
  
  //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).
  fTrack->SetFirstPoint(x0,y0,0); //Z-value is set in FitLine

  psi  = (Double_t)atan2(bcent-y0,acent-x0) ;
  psi  = psi + q * 0.5F * pi ;
  if ( psi < 0 ) psi = psi + 2*pi;
  pt   = (Double_t)(BFACT * AliL3Transform::GetBField() * radius ) ;
  
  //Update the track parameters with the parameters from this fit:
  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 ) ;
//
  return 0 ;
  
}

//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
//    Fit Line in s-z plane
//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Int_t AliL3ConfMapFit::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() / ( BFACT * AliL3Transform::GetBField() ) ) ;

  //TObjArray *hits = fTrack->GetHits();
  //Int_t num_of_hits = fTrack->GetNumberOfPoints();

  if ( fTrack->ComesFromMainVertex() == true ) 
    {
      dx = ((AliL3ConfMapPoint*)fTrack->firstHit)->GetX() - fVertex->GetX();
      dy = ((AliL3ConfMapPoint*)fTrack->firstHit)->GetY() - fVertex->GetY() ;
    }
  else 
    {
      dx = ((AliL3ConfMapPoint *)fTrack->firstHit)->GetX() - ((AliL3ConfMapPoint *)fTrack->lastHit)->GetX() ;
      dy = ((AliL3ConfMapPoint *)fTrack->firstHit)->GetY() - ((AliL3ConfMapPoint *)fTrack->lastHit)->GetY() ;
      //dx = ((AliL3ConfMapPoint *)hits->First())->GetX() - ((AliL3ConfMapPoint *)hits->Last())->GetX() ;
      //dy = ((AliL3ConfMapPoint *)hits->First())->GetY() - ((AliL3ConfMapPoint *)hits->Last())->GetY() ;
    }
  
  Double_t localPsi = 0.5F * sqrt ( dx*dx + dy*dy ) / radius ;
  Double_t total_s ;
  
  if ( fabs(localPsi) < 1. ) 
    {
      total_s = 2.0 * radius * asin ( localPsi ) ;
    } 
  else 
    { 
      total_s = 2.0 * radius * pi ;
    } 
  
  AliL3ConfMapPoint *previousHit = NULL;

  // FtfBaseHit *previousHit = 0  ;
  
  //for ( startLoop() ; done() ; nextHit() ) {
  Double_t dpsi,s;

  //  for(hit_counter=0; hit_counter<num_of_hits; hit_counter++)
  for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())  
    {
      // AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)hits->At(hit_counter);
      AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)fTrack->currentHit;
      // if ( currentHit != firstHit ) 
      if(cHit != fTrack->firstHit)//  hits->First())
	{
	  dx   = cHit->GetX() - previousHit->GetX() ;
	  dy   = cHit->GetY() - previousHit->GetY() ;
	  dpsi = 0.5 * (Double_t)sqrt ( dx*dx + dy*dy ) / radius ;
	  fTrack->SetPsierr(dpsi);
	  s = previousHit->GetS() - 2.0 * radius * (Double_t)asin ( dpsi ) ;
	  cHit->SetS(s);
	}
      else
	cHit->SetS(total_s);
      //	cHit->s = total_s ;
    
      sum += cHit->GetZWeight() ;
      ss  += cHit->GetZWeight() * cHit->GetS() ;
      sz  += cHit->GetZWeight() * cHit->GetZ() ;
      sss += cHit->GetZWeight() * cHit->GetS() * cHit->GetS() ;
      ssz += cHit->GetZWeight() * cHit->GetS() * cHit->GetZ() ;
      previousHit = cHit ;
    }
  
  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(hit_counter=0; hit_counter<num_of_hits; hit_counter++)
  for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())  
    {
      //AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)hits->At(hit_counter);
      AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)fTrack->currentHit;
      r1   = cHit->GetZ() - tanl * cHit->GetS() - z0 ;
      chi2 += (Double_t) ( (Double_t)cHit->GetZWeight() * (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);
  
  return 0 ;
}
Commit	Line	Data
3e87ef69	1	// @(#) $Id$
9392f4fd	2
b661165c	3	// Author: Anders Vestbo <mailto:vestbo@fi.uib.no>
3e87ef69	4	//*-- Copyright &copy ALICE HLT Group
b661165c	5
118c26c3	6	#include "AliL3StandardIncludes.h"
108615fc	7
	8	#include "AliL3Logging.h"
	9	#include "AliL3ConfMapFit.h"
	10	#include "AliL3Vertex.h"
	11	#include "AliL3ConfMapTrack.h"
	12	#include "AliL3ConfMapPoint.h"
ef79795d	13	#include "AliL3Transform.h"
108615fc	14
3e87ef69	15	/** \class AliL3ConfMapFit
3e87ef69	16	<pre>
b661165c	17	//_____________________________________________________________
108615fc	18	// AliL3ConfMapFit
	19	//
	20	// Fit class for conformal mapping tracking
3e87ef69	21	</pre>
3e87ef69	22	*/
108615fc	23
	24	ClassImp(AliL3ConfMapFit)
	25
	26	Double_t AliL3ConfMapFit::pi=3.14159265358979323846;
	27
	28	AliL3ConfMapFit::AliL3ConfMapFit(AliL3ConfMapTrack track,AliL3Vertex vertex)
	29	{
	30	//constructor
	31	fTrack = track;
	32	fVertex = vertex;
	33	BFACT = 0.0029980;
108615fc	34
	35	}
	36
	37	Int_t AliL3ConfMapFit::FitHelix()
	38	{
	39	if(FitCircle())
	40	{
	41	LOG(AliL3Log::kError,"AliL3ConfMapFit::FitHelix","TrackFit")<<AliL3Log::kDec<<
	42	"Problems during circle fit"<<ENDLOG;
	43	return 1;
	44	}
	45	if(FitLine())
	46	{
	47	LOG(AliL3Log::kError,"AliL3ConfMapFit::FitHelix","TrackFit")<<AliL3Log::kDec<<
	48	"Problems during line fit"<<ENDLOG;
	49	return 1;
	50	}
	51	return 0;
	52	}
	53
	54	Int_t AliL3ConfMapFit::FitCircle()
	55	{
	56	//-----------------------------------------------------------------
	57	//Fits circle parameters using algorithm
	58	//described by ChErnov and Oskov in Computer Physics
	59	//Communications.
	60	//
	61	//Written in FORTRAN by Jawluen Tang, Physics department , UT-Austin
	62	//Moved to C by Pablo Yepes
	63	//Moved to AliROOT by ASV.
	64	//------------------------------------------------------------------
	65
	66	Double_t wsum = 0.0 ;
	67	Double_t xav = 0.0 ;
	68	Double_t yav = 0.0 ;
	69
	70	Int_t num_of_hits = fTrack->GetNumberOfPoints();
	71	//
	72	// Loop over hits calculating average
	73	Int_t co=0;
	74
	75	for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
	76	{
	77	co++;
	78	AliL3ConfMapPoint cHit = (AliL3ConfMapPoint)fTrack->currentHit;
	79	cHit->SetXYWeight( 1./ (Double_t)(cHit->GetXerr()cHit->GetXerr() + cHit->GetYerr()cHit->GetYerr()) );
	80	wsum += cHit->GetXYWeight() ;
	81	xav += cHit->GetXYWeight() * cHit->GetX() ;
	82	yav += cHit->GetXYWeight() * cHit->GetY() ;
	83	}
	84	if(co!=num_of_hits)
	85	LOG(AliL3Log::kError,"AliL3ConfMapFit::FitCircle","TrackFit")<<AliL3Log::kDec<<
	86	"Mismatch of hits. Counter: "<<co<<" nHits: "<<num_of_hits<<ENDLOG;
	87	if (fTrack->ComesFromMainVertex() == true)
	88	{
	89	wsum += fVertex->GetXYWeight() ;
	90	xav += fVertex->GetX() ;
	91	yav += fVertex->GetY() ;
	92	}
	93
	94	xav = xav / wsum ;
	95	yav = yav / wsum ;
	96	//
	97	// CALCULATE <X2>, <XY>, AND <Y2> WITH <X> = 0, & <Y> = 0
98	//
99	Double_t xxav = 0.0 ;
100	Double_t xyav = 0.0 ;
101	Double_t yyav = 0.0 ;
102	Double_t xi, yi ;
103
104	for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
105	{
106	//AliL3ConfMapPoint cHit = (AliL3ConfMapPoint )hits->At(hit_counter);
107	AliL3ConfMapPoint cHit = (AliL3ConfMapPoint)fTrack->currentHit;
108	xi = cHit->GetX() - xav ;
109	yi = cHit->GetY() - yav ;
110	xxav += xi * xi * cHit->GetXYWeight() ;
111	xyav += xi * yi * cHit->GetXYWeight() ;
112	yyav += yi * yi * cHit->GetXYWeight() ;
113	}
114
115	if (fTrack->ComesFromMainVertex() == true)
116	{
117	xi = fVertex->GetX() - xav ;
118	yi = fVertex->GetY() - yav ;
119	xxav += xi * xi * fVertex->GetXYWeight() ;
120	xyav += xi * yi * fVertex->GetXYWeight() ;
121	yyav += yi * yi * fVertex->GetXYWeight() ;
122	}
123	xxav = xxav / wsum ;
124	xyav = xyav / wsum ;
125	yyav = yyav / wsum ;
126	//
127	//--> ROTATE COORDINATES SO THAT <XY> = 0
128	//
129	//--> SIGN(C2 - S2) = SIGN(XXAV - YYAV) >
130	//--> & > ==> NEW : (XXAV-YYAV) > 0
131	//--> SIGN(S) = SIGN(XYAV) >
132
133	Double_t a = fabs( xxav - yyav ) ;
134	Double_t b = 4.0 * xyav * xyav ;
135
136	Double_t asqpb = a * a + b ;
137	Double_t rasqpb = sqrt ( asqpb) ;
138
139	Double_t splus = 1.0 + a / rasqpb ;
140	Double_t sminus = b / (asqpb * splus) ;
141
142	splus = sqrt (0.5 * splus ) ;
143	sminus = sqrt (0.5 * sminus) ;
144	//
145	//-> FIRST REQUIRE : SIGN(C2 - S2) = SIGN(XXAV - YYAV)
146	//
147	Double_t sinrot, cosrot ;
148	if ( xxav <= yyav ) {
149	cosrot = sminus ;
150	sinrot = splus ;
151	}
152	else {
153	cosrot = splus ;
154	sinrot = sminus ;
155	}
156	//
157	//-> REQUIRE : SIGN(S) = SIGN(XYAV) * SIGN(C) (ASSUMING SIGN(C) > 0)
158	//
159	if ( xyav < 0.0 ) sinrot = - sinrot ;
160	//
161	//--> WE NOW HAVE THE SMALLEST ANGLE THAT GUARANTEES <X2> > <Y2>
162	//--> TO GET THE SIGN OF THE CHARGE RIGHT, THE NEW X-AXIS MUST POINT
163	//--> OUTWARD FROM THE ORGIN. WE ARE FREE TO CHANGE SIGNS OF BOTH
164	//--> COSROT AND SINROT SIMULTANEOUSLY TO ACCOMPLISH THIS.
165	//
166	//--> CHOOSE SIGN OF C WISELY TO BE ABLE TO GET THE SIGN OF THE CHARGE
167	//
168	if ( cosrotxav+sinrotyav < 0.0 ) {
169	cosrot = -cosrot ;
170	sinrot = -sinrot ;
171	}
172	//
173	//-> NOW GET <R2> AND RSCALE= SQRT(<R2>)
174	//
175	Double_t rrav = xxav + yyav ;
176	Double_t rscale = sqrt(rrav) ;
177
178	xxav = 0.0 ;
179	yyav = 0.0 ;
180	xyav = 0.0 ;
181	Double_t xrrav = 0.0 ;
182	Double_t yrrav = 0.0 ;
183	Double_t rrrrav = 0.0 ;
184
185	Double_t xixi, yiyi, riri, wiriri, xold, yold ;
186
187	//for (hit_counter=0; hit_counter<num_of_hits; hit_counter++)
188	for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
189	{
190	//AliL3ConfMapPoint cHit = (AliL3ConfMapPoint)hits->At(hit_counter);
191	AliL3ConfMapPoint* cHit = (AliL3ConfMapPoint*)fTrack->currentHit;
192
193	xold = cHit->GetX() - xav ;
194	yold = cHit->GetY() - yav ;
195	//
196	//--> ROTATE SO THAT <XY> = 0 & DIVIDE BY RSCALE SO THAT <R**2> = 1
197	//
198	xi = ( cosrot * xold + sinrot * yold ) / rscale ;
199	yi = ( -sinrot * xold + cosrot * yold ) / rscale ;
200
201	xixi = xi * xi ;
202	yiyi = yi * yi ;
203	riri = xixi + yiyi ;
204	wiriri = cHit->GetXYWeight() * riri ;
205
206	xyav += cHit->GetXYWeight() * xi * yi ;
207	xxav += cHit->GetXYWeight() * xixi ;
208	yyav += cHit->GetXYWeight() * yiyi ;
209
210	xrrav += wiriri * xi ;
211	yrrav += wiriri * yi ;
212	rrrrav += wiriri * riri ;
213	}
214	//
215	// Include vertex if required
216	//
217	if (fTrack->ComesFromMainVertex() == true)
218	{
219	xold = fVertex->GetX() - xav ;
220	yold = fVertex->GetY() - yav ;
221	//
222	//--> ROTATE SO THAT <XY> = 0 & DIVIDE BY RSCALE SO THAT <R**2> = 1
223	//
224	xi = ( cosrot * xold + sinrot * yold ) / rscale ;
225	yi = ( -sinrot * xold + cosrot * yold ) / rscale ;
226
227	xixi = xi * xi ;
228	yiyi = yi * yi ;
229	riri = xixi + yiyi ;
230	wiriri = fVertex->GetXYWeight() * riri ;
231
232	xyav += fVertex->GetXYWeight() * xi * yi ;
233	xxav += fVertex->GetXYWeight() * xixi ;
234	yyav += fVertex->GetXYWeight() * yiyi ;
235
236	xrrav += wiriri * xi ;
237	yrrav += wiriri * yi ;
238	rrrrav += wiriri * riri ;
239	}
240	//
241	//
242	//
243	//--> DIVIDE BY WSUM TO MAKE AVERAGES
244	//
245	xxav = xxav / wsum ;
246	yyav = yyav / wsum ;
247	xrrav = xrrav / wsum ;
248	yrrav = yrrav / wsum ;
249	rrrrav = rrrrav / wsum ;
250	xyav = xyav / wsum ;
251
252	Int_t const ntry = 5 ;
253	//
254	//--> USE THESE TO GET THE COEFFICIENTS OF THE 4-TH ORDER POLYNIMIAL
255	//--> DON'T PANIC - THE THIRD ORDER TERM IS ZERO !
256	//
257	Double_t xrrxrr = xrrav * xrrav ;
258	Double_t yrryrr = yrrav * yrrav ;
259	Double_t rrrrm1 = rrrrav - 1.0 ;
260	Double_t xxyy = xxav * yyav ;
261
262	Double_t c0 = rrrrm1xxyy - xrrxrryyav - yrryrr*xxav ;
263	Double_t c1 = - rrrrm1 + xrrxrr + yrryrr - 4.0*xxyy ;
264	Double_t c2 = 4.0 + rrrrm1 - 4.0*xxyy ;
265	Double_t c4 = - 4.0 ;
266	//
267	//--> COEFFICIENTS OF THE DERIVATIVE - USED IN NEWTON-RAPHSON ITERATIONS
268	//
269	Double_t c2d = 2.0 * c2 ;
270	Double_t c4d = 4.0 * c4 ;
271	//
272	//--> 0'TH VALUE OF LAMDA - LINEAR INTERPOLATION BETWEEN P(0) & P(YYAV)
273	//
274	// LAMDA = YYAV * C0 / (C0 + YRRSQ * (XXAV-YYAV))
275	Double_t lamda = 0.0 ;
276	Double_t dlamda = 0.0 ;
277	//
278	Double_t chiscl = wsum * rscale * rscale ;
279	Double_t dlamax = 0.001 / chiscl ;
280
281	Double_t p, pd ;
282	for ( int itry = 1 ; itry <= ntry ; itry++ ) {
283	p = c0 + lamda * (c1 + lamda * (c2 + lamda * lamda * c4 )) ;
284	pd = (c1 + lamda * (c2d + lamda * lamda * c4d)) ;
285	dlamda = -p / pd ;
286	lamda = lamda + dlamda ;
287	if (fabs(dlamda)< dlamax) break ;
288	}
289
290	Double_t chi2 = (Double_t)(chiscl * lamda) ;
291
292	fTrack->SetChiSq1(chi2);
293	// Double_t dchisq = chiscl * dlamda ;
294	//
295	//--> NOW CALCULATE THE MATRIX ELEMENTS FOR ALPHA, BETA & KAPPA
296	//
297	Double_t h11 = xxav - lamda ;
298	Double_t h14 = xrrav ;
299	Double_t h22 = yyav - lamda ;
300	Double_t h24 = yrrav ;
301	Double_t h34 = 1.0 + 2.0*lamda ;
302	if ( h11 == 0.0 \|\| h22 == 0.0 ){
303	LOG(AliL3Log::kError,"AliL3ConfMapFit::FitCircle","TrackFit")<<AliL3Log::kDec<<
304	"Problems fitting circle"<<ENDLOG;
305	return 1 ;
306	}
307	Double_t rootsq = (h14h14)/(h11h11) + 4.0*h34 ;
308
309	Double_t ratio, kappa, beta ;
310	if ( fabs(h22) > fabs(h24) ) {
311	ratio = h24 / h22 ;
312	rootsq = ratio * ratio + rootsq ;
313	kappa = 1.0 / sqrt(rootsq) ;
314	beta = - ratio * kappa ;
315	}
316	else {
317	ratio = h22 / h24 ;
318	rootsq = 1.0 + ratio * ratio * rootsq ;
319	beta = 1.0 / sqrt(rootsq) ;
320	if ( h24 > 0 ) beta = - beta ;
321	kappa = -ratio * beta ;
322	}
323	Double_t alpha = - (h14/h11) * kappa ;
324	//
325	//--> transform these into the lab coordinate system
326	//--> first get kappa and back to real dimensions
327	//
328	Double_t kappa1 = kappa / rscale ;
329	Double_t dbro = 0.5 / kappa1 ;
330	//
331	//--> next rotate alpha and beta and scale
332	//
333	Double_t alphar = (cosrot * alpha - sinrot * beta)* dbro ;
334	Double_t betar = (sinrot * alpha + cosrot * beta)* dbro ;
335	//
336	//--> then translate by (xav,yav)
337	//
338	Double_t acent = (double)(xav - alphar) ;
339	Double_t bcent = (double)(yav - betar ) ;
340	Double_t radius = (double)dbro ;
341	//
342	// Get charge
343	//
5dd30052	344	Int_t q = ( ( yrrav < 0 ) ? 1 : -1 ) ;
108615fc	345
	346	fTrack->SetCharge(q);
	347
	348	//
	349	// Get other track parameters
	350	//
	351	Double_t x0, y0,phi0,r0,psi,pt ;
	352	if ( fTrack->ComesFromMainVertex() == true )
	353	{
	354	//flag = 1 ; // primary track flag
	355	x0 = fVertex->GetX() ;
	356	y0 = fVertex->GetY() ;
	357	phi0 = fVertex->GetPhi() ;
	358	r0 = fVertex->GetR() ;
	359	fTrack->SetPhi0(phi0);
	360	fTrack->SetR0(r0);
	361	}
	362	else
	363	{
	364	//AliL3ConfMapPoint lHit = (AliL3ConfMapPoint)hits->Last();
	365	AliL3ConfMapPoint lHit = (AliL3ConfMapPoint)fTrack->lastHit;
	366	//flag = 0 ; // primary track flag
	367	x0 = lHit->GetX() ;
	368	y0 = lHit->GetY() ;
	369	phi0 = atan2(lHit->GetY(),lHit->GetX());
	370	if ( phi0 < 0 ) phi0 += 2*pi;
	371	r0 = sqrt ( lHit->GetX() * lHit->GetX() + lHit->GetY() * lHit->GetY() ) ;
	372	fTrack->SetPhi0(phi0);
	373	fTrack->SetR0(r0);
1f1942b8	374
108615fc	375	}
1f1942b8	376
	377	//Set the first point on the track to the space point coordinates of the innermost track
	378	//This will be updated to lie on the fit later on (AliL3Track::UpdateToFirstPoint).
	379	fTrack->SetFirstPoint(x0,y0,0); //Z-value is set in FitLine
	380
108615fc	381	psi = (Double_t)atan2(bcent-y0,acent-x0) ;
	382	psi = psi + q * 0.5F * pi ;
	383	if ( psi < 0 ) psi = psi + 2*pi;
ef79795d	384	pt = (Double_t)(BFACT * AliL3Transform::GetBField() * radius ) ;
1f1942b8	385
1f1942b8	386	//Update the track parameters with the parameters from this fit:
108615fc	387	fTrack->SetPsi(psi);
108615fc	388	fTrack->SetPt(pt);
1f1942b8	389	fTrack->SetRadius(radius);
	390	fTrack->SetCenterX(acent);
	391	fTrack->SetCenterY(bcent);
108615fc	392
	393	//
	394	// Get errors from fast fit
	395	//
	396	//if ( getPara()->getErrors ) getErrorsCircleFit ( acent, bcent, radius ) ;
	397	//
	398	return 0 ;
	399
	400	}
	401
	402	//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
	403	// Fit Line in s-z plane
	404	//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
	405	Int_t AliL3ConfMapFit::FitLine ( )
	406	{
	407	//
	408	//Initialization
	409	//
	410	Double_t sum = 0.F ;
	411	Double_t ss = 0.F ;
	412	Double_t sz = 0.F ;
	413	Double_t sss = 0.F ;
	414	Double_t ssz = 0.F ;
	415	//
	416	//find sum , sums ,sumz, sumss
	417	//
	418	Double_t dx, dy ;
ef79795d	419	Double_t radius = (Double_t)(fTrack->GetPt() / ( BFACT * AliL3Transform::GetBField() ) ) ;
108615fc	420
	421	//TObjArray *hits = fTrack->GetHits();
	422	//Int_t num_of_hits = fTrack->GetNumberOfPoints();
	423
	424	if ( fTrack->ComesFromMainVertex() == true )
	425	{
	426	dx = ((AliL3ConfMapPoint*)fTrack->firstHit)->GetX() - fVertex->GetX();
	427	dy = ((AliL3ConfMapPoint*)fTrack->firstHit)->GetY() - fVertex->GetY() ;
	428	}
	429	else
	430	{
	431	dx = ((AliL3ConfMapPoint )fTrack->firstHit)->GetX() - ((AliL3ConfMapPoint )fTrack->lastHit)->GetX() ;
	432	dy = ((AliL3ConfMapPoint )fTrack->firstHit)->GetY() - ((AliL3ConfMapPoint )fTrack->lastHit)->GetY() ;
	433	//dx = ((AliL3ConfMapPoint )hits->First())->GetX() - ((AliL3ConfMapPoint )hits->Last())->GetX() ;
	434	//dy = ((AliL3ConfMapPoint )hits->First())->GetY() - ((AliL3ConfMapPoint )hits->Last())->GetY() ;
	435	}
	436
	437	Double_t localPsi = 0.5F * sqrt ( dxdx + dydy ) / radius ;
	438	Double_t total_s ;
	439
	440	if ( fabs(localPsi) < 1. )
	441	{
	442	total_s = 2.0 * radius * asin ( localPsi ) ;
	443	}
	444	else
	445	{
	446	total_s = 2.0 * radius * pi ;
	447	}
	448
	449	AliL3ConfMapPoint *previousHit = NULL;
	450
	451	// FtfBaseHit *previousHit = 0 ;
	452
	453	//for ( startLoop() ; done() ; nextHit() ) {
	454	Double_t dpsi,s;
	455
	456	// for(hit_counter=0; hit_counter<num_of_hits; hit_counter++)
	457	for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
	458	{
	459	// AliL3ConfMapPoint cHit = (AliL3ConfMapPoint)hits->At(hit_counter);
	460	AliL3ConfMapPoint cHit = (AliL3ConfMapPoint)fTrack->currentHit;
	461	// if ( currentHit != firstHit )
	462	if(cHit != fTrack->firstHit)// hits->First())
	463	{
	464	dx = cHit->GetX() - previousHit->GetX() ;
	465	dy = cHit->GetY() - previousHit->GetY() ;
	466	dpsi = 0.5 * (Double_t)sqrt ( dxdx + dydy ) / radius ;
	467	fTrack->SetPsierr(dpsi);
	468	s = previousHit->GetS() - 2.0 * radius * (Double_t)asin ( dpsi ) ;
	469	cHit->SetS(s);
	470	}
	471	else
	472	cHit->SetS(total_s);
	473	// cHit->s = total_s ;
	474
	475	sum += cHit->GetZWeight() ;
	476	ss += cHit->GetZWeight() * cHit->GetS() ;
	477	sz += cHit->GetZWeight() * cHit->GetZ() ;
	478	sss += cHit->GetZWeight() * cHit->GetS() * cHit->GetS() ;
	479	ssz += cHit->GetZWeight() * cHit->GetS() * cHit->GetZ() ;
	480	previousHit = cHit ;
	481	}
	482
	483	Double_t chi2,det = sum * sss - ss * ss;
484	if ( fabs(det) < 1e-20)
485	{
486	chi2 = 99999.F ;
487	fTrack->SetChiSq2(chi2);
488	return 0 ;
489	}
490
491	//Compute the best fitted parameters A,B
492	Double_t tanl,z0,dtanl,dz0;
493
494	tanl = (Double_t)((sum * ssz - ss * sz ) / det );
495	z0 = (Double_t)((sz * sss - ssz * ss ) / det );
496
497	fTrack->SetTgl(tanl);
498	fTrack->SetZ0(z0);
499
500	// calculate chi-square
501
502	chi2 = 0.;
503	Double_t r1 ;
504
505	//for(hit_counter=0; hit_counter<num_of_hits; hit_counter++)
506	for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
507	{
508	//AliL3ConfMapPoint cHit = (AliL3ConfMapPoint)hits->At(hit_counter);
509	AliL3ConfMapPoint cHit = (AliL3ConfMapPoint)fTrack->currentHit;
510	r1 = cHit->GetZ() - tanl * cHit->GetS() - z0 ;
511	chi2 += (Double_t) ( (Double_t)cHit->GetZWeight() * (r1 * r1) );
512	}
513	fTrack->SetChiSq2(chi2);
514	//
515	// calculate estimated variance
516	// varsq=chi/(double(n)-2.)
517	// calculate covariance matrix
518	// siga=sqrt(varsq*sxx/det)
519	// sigb=sqrt(varsq*sum/det)
520	//
521	dtanl = (Double_t) ( sum / det );
522	dz0 = (Double_t) ( sss / det );
523
524	fTrack->SetTglerr(dtanl);
525	fTrack->SetZ0err(dz0);
526
527	return 0 ;
528	}