X-Git-Url: http://git.uio.no/git/?p=u%2Fmrichter%2FAliRoot.git;a=blobdiff_plain;f=ITS%2FAliITStrackV2.cxx;h=35cfdccd8b544ac244441af1dcc7f4b5354db978;hp=39024ac1f26a4491cfe338ef8cb82ffe462afcad;hb=15dd636fe2589363908aa2f48504ba5fab2d5763;hpb=60e5fcc321959d9940472cc539381033ac9e1eb7

diff --git a/ITS/AliITStrackV2.cxx b/ITS/AliITStrackV2.cxx
index 39024ac1f26..35cfdccd8b5 100644
--- a/ITS/AliITStrackV2.cxx
+++ b/ITS/AliITStrackV2.cxx
@@ -17,55 +17,109 @@
 //                Implementation of the ITS track class
 //
 //          Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
+//     dEdx analysis by: Boris Batyunya, JINR, Boris.Batiounia@cern.ch
 //-------------------------------------------------------------------------
 
 #include <TMatrixD.h>
 
 #include <TMath.h>
-#include <iostream.h>
 
 #include "AliCluster.h"
-#include "../TPC/AliTPCtrack.h"
+#include "AliESDtrack.h"
 #include "AliITStrackV2.h"
 
 ClassImp(AliITStrackV2)
 
-const Int_t kWARN=1;
+const Int_t kWARN=5;
 
 //____________________________________________________________________________
-AliITStrackV2::AliITStrackV2(const AliTPCtrack& t) throw (const Char_t *) {
+AliITStrackV2::AliITStrackV2():AliKalmanTrack(),
+  fX(0),
+  fAlpha(0),
+  fdEdx(0),
+  fP0(0),
+  fP1(0),
+  fP2(0),
+  fP3(0),
+  fP4(0),
+  fC00(0),
+  fC10(0),
+  fC11(0),
+  fC20(0),
+  fC21(0),
+  fC22(0),
+  fC30(0),
+  fC31(0),
+  fC32(0),
+  fC33(0),
+  fC40(0),
+  fC41(0),
+  fC42(0),
+  fC43(0),
+  fC44(0),
+  fESDtrack(0)
+{
+    for(Int_t i=0; i<kMaxLayer; i++) fIndex[i]=0;
+    for(Int_t i=0; i<4; i++) fdEdxSample[i]=0;
+}
+
+
+//____________________________________________________________________________
+AliITStrackV2::AliITStrackV2(AliESDtrack& t,Bool_t c) throw (const Char_t *) :
+AliKalmanTrack() {
   //------------------------------------------------------------------
-  //Convertion TPC track -> ITS track
+  // Conversion ESD track -> ITS track.
+  // If c==kTRUE, create the ITS track out of the constrained params.
   //------------------------------------------------------------------
+  SetNumberOfClusters(t.GetITSclusters(fIndex));
   SetLabel(t.GetLabel());
-  SetChi2(0.);
-  SetNumberOfClusters(0);
-  fdEdx  = 0.;
+  SetMass(t.GetMass());
+  //
+  //
+
+  fdEdx=t.GetITSsignal();
   fAlpha = t.GetAlpha();
   if      (fAlpha < -TMath::Pi()) fAlpha += 2*TMath::Pi();
   else if (fAlpha >= TMath::Pi()) fAlpha -= 2*TMath::Pi();
 
-  //Convertion of the track parameters
-  Double_t x,p[5]; t.GetExternalParameters(x,p);
-  fX=x;    x=kConversionConstant;
+  //Conversion of the track parameters
+  Double_t x,p[5]; 
+  if (c) t.GetConstrainedExternalParameters(x,p);
+  else t.GetExternalParameters(x,p);
+  fX=x;    x=GetConvConst();
   fP0=p[0]; 
   fP1=p[1]; 
   fP2=p[2];
   fP3=p[3];
   fP4=p[4]/x; 
 
-  //Convertion of the covariance matrix
-  Double_t c[15]; t.GetExternalCovariance(c);
-
-  fC00=c[0 ];
-  fC10=c[1 ];   fC11=c[2 ];
-  fC20=c[3 ];   fC21=c[4 ];   fC22=c[5 ];
-  fC30=c[6 ];   fC31=c[7 ];   fC32=c[8 ];   fC33=c[9 ];
-  fC40=c[10]/x; fC41=c[11]/x; fC42=c[12]/x; fC43=c[13]/x; fC44=c[14]/x/x;
+  //Conversion of the covariance matrix
+  Double_t cv[15]; 
+  if (c) t.GetConstrainedExternalCovariance(cv);
+  else t.GetExternalCovariance(cv);
+  fC00=cv[0 ];
+  fC10=cv[1 ];   fC11=cv[2 ];
+  fC20=cv[3 ];   fC21=cv[4 ];   fC22=cv[5 ];
+  fC30=cv[6 ];   fC31=cv[7 ];   fC32=cv[8 ];   fC33=cv[9 ];
+  fC40=cv[10]/x; fC41=cv[11]/x; fC42=cv[12]/x; fC43=cv[13]/x; fC44=cv[14]/x/x;
+
+  if (t.GetStatus()&AliESDtrack::kTIME) {
+    StartTimeIntegral();
+    Double_t times[10]; t.GetIntegratedTimes(times); SetIntegratedTimes(times);
+    SetIntegratedLength(t.GetIntegratedLength());
+  }
+  fESDtrack=&t;
 
   if (!Invariant()) throw "AliITStrackV2: conversion failed !\n";
 }
 
+void AliITStrackV2::UpdateESDtrack(ULong_t flags) const {
+  fESDtrack->UpdateTrackParams(this,flags);
+}
+void AliITStrackV2::SetConstrainedESDtrack(Double_t chi2) const {
+  fESDtrack->SetConstrainedTrackParams(this,chi2);
+}
+
 //____________________________________________________________________________
 AliITStrackV2::AliITStrackV2(const AliITStrackV2& t) : AliKalmanTrack(t) {
   //------------------------------------------------------------------
@@ -84,7 +138,11 @@ AliITStrackV2::AliITStrackV2(const AliITStrackV2& t) : AliKalmanTrack(t) {
   fC40=t.fC40;  fC41=t.fC41;  fC42=t.fC42;  fC43=t.fC43;  fC44=t.fC44;
 
   Int_t n=GetNumberOfClusters();
-  for (Int_t i=0; i<n; i++) fIndex[i]=t.fIndex[i];
+  for (Int_t i=0; i<n; i++) {
+    fIndex[i]=t.fIndex[i];
+    if (i<4) fdEdxSample[i]=t.fdEdxSample[i];
+  }
+  fESDtrack=t.fESDtrack;
 }
 
 //_____________________________________________________________________________
@@ -92,9 +150,11 @@ Int_t AliITStrackV2::Compare(const TObject *o) const {
   //-----------------------------------------------------------------
   // This function compares tracks according to the their curvature
   //-----------------------------------------------------------------
-  AliTPCtrack *t=(AliTPCtrack*)o;
-  Double_t co=TMath::Abs(t->Get1Pt());
-  Double_t c =TMath::Abs(Get1Pt());
+  AliITStrackV2 *t=(AliITStrackV2*)o;
+  //Double_t co=TMath::Abs(t->Get1Pt());
+  //Double_t c =TMath::Abs(Get1Pt());
+  Double_t co=t->GetSigmaY2()*t->GetSigmaZ2();
+  Double_t c =GetSigmaY2()*GetSigmaZ2();
   if (c>co) return 1;
   else if (c<co) return -1;
   return 0;
@@ -106,7 +166,7 @@ void AliITStrackV2::GetExternalCovariance(Double_t cc[15]) const {
   // This function returns an external representation of the covriance matrix.
   //   (See comments in AliTPCtrack.h about external track representation)
   //-------------------------------------------------------------------------
-  Double_t a=kConvConst;
+  Double_t a=GetConvConst();
 
   cc[0 ]=fC00;
   cc[1 ]=fC10;   cc[2 ]=fC11;
@@ -116,13 +176,15 @@ void AliITStrackV2::GetExternalCovariance(Double_t cc[15]) const {
 }
 
 //____________________________________________________________________________
-Int_t AliITStrackV2::PropagateToVertex(Double_t x0,Double_t rho,Double_t pm) {
+Int_t AliITStrackV2::PropagateToVertex(Double_t d,Double_t x0) {
   //------------------------------------------------------------------
   //This function propagates a track to the minimal distance from the origin
   //------------------------------------------------------------------
-  Double_t xv=fP2*(fX*fP2 - fP0*TMath::Sqrt(1.- fP2*fP2)); //linear approxim.
-  Propagate(fAlpha,xv,0.,0.,pm);   
-  return 0;
+  //Double_t xv=fP2*(fX*fP2 - fP0*TMath::Sqrt(1.- fP2*fP2)); //linear approxim.
+  Double_t tgf=-(fP4*fX - fP2)/(fP4*fP0 + TMath::Sqrt(1 - fP2*fP2));
+  Double_t snf=tgf/TMath::Sqrt(1.+ tgf*tgf);
+  Double_t xv=(snf - fP2)/fP4 + fX;
+  return PropagateTo(xv,d,x0);
 }
 
 //____________________________________________________________________________
@@ -133,9 +195,10 @@ GetGlobalXYZat(Double_t xk, Double_t &x, Double_t &y, Double_t &z) const {
   //------------------------------------------------------------------
   Double_t dx=xk-fX;
   Double_t f1=fP2, f2=f1 + fP4*dx;
-  if (TMath::Abs(f2) >= 0.99999) {
-     Int_t n=GetNumberOfClusters();
-    if (n>kWARN) cerr<<n<<" AliITStrackV2 warning: Propagation failed !\n";
+  if (TMath::Abs(f2) >= 0.9999) {
+    Int_t n=GetNumberOfClusters();
+    if (n>kWARN) 
+      Warning("GetGlobalXYZat","Propagation failed (%d) !\n",n);
     return 0;
   }
 
@@ -160,106 +223,72 @@ Double_t AliITStrackV2::GetPredictedChi2(const AliCluster *c) const
   //-----------------------------------------------------------------
   Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
   r00+=fC00; r01+=fC10; r11+=fC11;
-
+  //
   Double_t det=r00*r11 - r01*r01;
-  if (TMath::Abs(det) < 1.e-10) {
+  if (TMath::Abs(det) < 1.e-30) {
     Int_t n=GetNumberOfClusters();
-    if (n>4) cerr<<n<<" AliKalmanTrack warning: Singular matrix !\n";
+    if (n>kWARN) 
+      Warning("GetPredictedChi2","Singular matrix (%d) !\n",n);
     return 1e10;
   }
   Double_t tmp=r00; r00=r11; r11=tmp; r01=-r01;
-  
+
   Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
-  
+
   return (dy*r00*dy + 2*r01*dy*dz + dz*r11*dz)/det;
 }
 
-//_____________________________________________________________________________
-Double_t AliITStrackV2::GetPredictedChi2(const AliCluster *c,Double_t *m,
-Double_t x0, Double_t pm) const {
-  //-----------------------------------------------------------------
-  // This function calculates a chi2 increment with a vertex contraint 
-  //-----------------------------------------------------------------
-  TVectorD x(5); x(0)=fP0; x(1)=fP1; x(2)=fP2; x(3)=fP3; x(4)=fP4;
-  TMatrixD C(5,5);
-  C(0,0)=fC00; 
-  C(1,0)=fC10; C(1,1)=fC11; 
-  C(2,0)=fC20; C(2,1)=fC21; C(2,2)=fC22;
-  C(3,0)=fC30; C(3,1)=fC31; C(3,2)=fC32; C(3,3)=fC33;
-  C(4,0)=fC40; C(4,1)=fC41; C(4,2)=fC42; C(4,3)=fC43; C(4,4)=fC44;
-
-  C(0,1)=C(1,0);
-  C(0,2)=C(2,0); C(1,2)=C(2,1);
-  C(0,3)=C(3,0); C(1,3)=C(3,1); C(2,3)=C(3,2);
-  C(0,4)=C(4,0); C(1,4)=C(4,1); C(2,4)=C(4,2); C(3,4)=C(4,3);
-
-  TMatrixD H(4,5); H.UnitMatrix();
-  Double_t dy=(c->GetY() - m[0]), dz=(c->GetZ() - m[1]);
+//____________________________________________________________________________
+Int_t AliITStrackV2::CorrectForMaterial(Double_t d, Double_t x0) {
+  //------------------------------------------------------------------
+  //This function corrects the track parameters for crossed material
+  //------------------------------------------------------------------
+  Double_t p2=(1.+ fP3*fP3)/(Get1Pt()*Get1Pt());
+  Double_t beta2=p2/(p2 + GetMass()*GetMass());
+  d*=TMath::Sqrt((1.+ fP3*fP3)/(1.- fP2*fP2));
 
-  Double_t dr=TMath::Sqrt(fX*fX + dy*dy);
-  Double_t r =TMath::Sqrt(4/dr/dr - fP4*fP4);
-  Double_t sn=0.5*(fP4*fX + dy*r);
-  Double_t tg=0.5*fP4*dz/TMath::ASin(0.5*fP4*dr);
-  TVectorD mm(4); 
-  mm(0)=m[0]=c->GetY(); mm(1)=m[1]=c->GetZ(); mm(2)=m[2]=sn; mm(3)=m[3]=tg;
+  //Multiple scattering******************
+  if (d!=0) {
+     Double_t theta2=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(d);
+     //Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*TMath::Abs(d)*9.36*2.33;
+     fC22 += theta2*(1.- fP2*fP2)*(1. + fP3*fP3);
+     fC33 += theta2*(1. + fP3*fP3)*(1. + fP3*fP3);
+     fC43 += theta2*fP3*fP4*(1. + fP3*fP3);
+     fC44 += theta2*fP3*fP4*fP3*fP4;
+  }
 
-  Double_t v22=0.,v33=0.;
-  //x0=0.;
+  //Energy losses************************
   if (x0!=0.) {
-     Double_t pp2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
-     Double_t beta2=pp2/(pp2 + pm*pm);
-     x0*=TMath::Sqrt((1.+ GetTgl()*GetTgl())/(1.- GetSnp()*GetSnp()));
-     Double_t theta2=14.1*14.1/(beta2*pp2*1e6)*x0;
-     v22 = theta2*(1.- GetSnp()*GetSnp())*(1. + GetTgl()*GetTgl());
-     v33 = theta2*(1.+ GetTgl()*GetTgl())*(1. + GetTgl()*GetTgl());
-  }
-  Double_t sy2=c->GetSigmaY2(), sz2=c->GetSigmaZ2();
-  v22+=kSigmaYV*kSigmaYV/dr/dr;
-  v22+=sy2/dr/dr;
-  Double_t v20=sy2/dr;
-
-  v33+=kSigmaZV*kSigmaZV/dr/dr;
-  v33+=sz2/dr/dr;
-  Double_t v31=sz2/dr;
-
-  TMatrixD V(4,4); 
-  V(0,0)=m[4 ]=sy2; V(0,1)=m[5 ]=0.;  V(0,2)=m[6 ]=v20; V(0,3)=m[7 ]=0.;
-  V(1,0)=m[8 ]=0.;  V(1,1)=m[9 ]=sz2; V(1,2)=m[10]=0.;  V(1,3)=m[11]=v31;
-  V(2,0)=m[12]=v20; V(2,1)=m[13]=0.;  V(2,2)=m[14]=v22; V(2,3)=m[15]=0.;
-  V(3,0)=m[16]=0.;  V(3,1)=m[17]=v31; V(3,2)=m[18]=0.;  V(3,3)=m[19]=v33;
-
-  TVectorD res=x;  res*=H; res-=mm; //res*=-1; 
-  TMatrixD tmp(H,TMatrixD::kMult,C);
-  TMatrixD R(tmp,TMatrixD::kMult,TMatrixD(TMatrixD::kTransposed,H)); R+=V;
-  
-  Double_t det=R.Determinant();
-  if (TMath::Abs(det) < 1.e-25) {
-    Int_t n=GetNumberOfClusters();
-    if (n>kWARN) cerr<<n<<" AliITStrackV2 warning: Singular matrix !\n";
-    return 1e10;
+     d*=x0;
+     Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*d;
+     if (beta2/(1-beta2)>3.5*3.5)
+       dE=0.153e-3/beta2*(log(3.5*5940)+0.5*log(beta2/(1-beta2)) - beta2)*d;
+
+     fP4*=(1.- TMath::Sqrt(p2+GetMass()*GetMass())/p2*dE);
   }
 
-  R.Invert();
+  if (!Invariant()) return 0;
 
-  TVectorD rs=res;
-  res*=R;
-  return rs*res;
+  return 1;
 }
 
 //____________________________________________________________________________
-Int_t 
-AliITStrackV2::PropagateTo(Double_t xk,Double_t x0,Double_t rho,Double_t pm) {
+Int_t AliITStrackV2::PropagateTo(Double_t xk, Double_t d, Double_t x0) {
   //------------------------------------------------------------------
   //This function propagates a track
   //------------------------------------------------------------------
   Double_t x1=fX, x2=xk, dx=x2-x1;
   Double_t f1=fP2, f2=f1 + fP4*dx;
-  if (TMath::Abs(f2) >= 0.99999) {
+  if (TMath::Abs(f2) >= 0.9999) {
     Int_t n=GetNumberOfClusters();
-    if (n>kWARN) cerr<<n<<" AliITStrackV2 warning: Propagation failed !\n";
+    if (n>kWARN) 
+       Warning("PropagateTo","Propagation failed !\n",n);
     return 0;
   }
 
+  // old position [SR, GSI, 17.02.2003]
+  Double_t oldX = fX, oldY = fP0, oldZ = fP1;
+
   Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
   
   fP0 += dx*(f1+f2)/(r1+r2);
@@ -308,29 +337,15 @@ AliITStrackV2::PropagateTo(Double_t xk,Double_t x0,Double_t rho,Double_t pm) {
 
   fX=x2;
 
-  Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
-  Double_t beta2=p2/(p2 + pm*pm);
+  if (!CorrectForMaterial(d,x0)) return 0;
 
-  //Multiple scattering******************
-  //x0=0.;
-  if (x0!=0) {
-     x0*=TMath::Sqrt((1.+ fP3*fP3)/(1.- fP2*fP2));
-     Double_t theta2=14.1*14.1/(beta2*p2*1e6)*x0;
-     fC22 += theta2*(1.- fP2*fP2)*(1. + fP3*fP3);
-     fC33 += theta2*(1. + fP3*fP3)*(1. + fP3*fP3);
-     fC43 += theta2*fP3*fP4*(1. + fP3*fP3);
-     fC44 += theta2*fP3*fP4*fP3*fP4;
+  // Integrated Time [SR, GSI, 17.02.2003]
+  if (IsStartedTimeIntegral() && fX>oldX) {
+    Double_t l2 = (fX-oldX)*(fX-oldX)+(fP0-oldY)*(fP0-oldY)+
+                  (fP1-oldZ)*(fP1-oldZ);
+    AddTimeStep(TMath::Sqrt(l2));
   }
-
-  //Energy losses************************
-  if (rho!=0.) {
-     rho*=TMath::Sqrt((1.+ fP3*fP3)/(1.- fP2*fP2));
-     Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*rho;
-     if (x1 < x2) dE=-dE;
-     fP4*=(1.- sqrt(p2+pm*pm)/p2*dE);
-  }
-
-  if (!Invariant()) {cout<<"Propagate !\n"; return 0;}
+  //
 
   return 1;
 }
@@ -353,6 +368,7 @@ Int_t AliITStrackV2::Update(const AliCluster* c, Double_t chi2, UInt_t index) {
   Double_t det=r00*r11 - r01*r01;
   Double_t tmp=r00; r00=r11/det; r11=tmp/det; r01=-r01/det;
 
+ 
   Double_t k00=fC00*r00+fC10*r01, k01=fC00*r01+fC10*r11;
   Double_t k10=fC10*r00+fC11*r01, k11=fC10*r01+fC11*r11;
   Double_t k20=fC20*r00+fC21*r01, k21=fC20*r01+fC21*r11;
@@ -361,13 +377,7 @@ Int_t AliITStrackV2::Update(const AliCluster* c, Double_t chi2, UInt_t index) {
 
   Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
   Double_t sf=fP2 + k20*dy + k21*dz;
-  /*
-  if (TMath::Abs(sf) >= 0.99999) {
-    Int_t n=GetNumberOfClusters();
-    if (n>kWARN) cerr<<n<<" AliITStrackV2 warning: Filtering failed !\n";
-    return 0;
-  }
-  */
+  
   fP0 += k00*dy + k01*dz;
   fP1 += k10*dy + k11*dz;
   fP2  = sf;
@@ -403,6 +413,8 @@ Int_t AliITStrackV2::Update(const AliCluster* c, Double_t chi2, UInt_t index) {
      return 0;
   }
 
+  if (chi2<0) return 1;
+
   Int_t n=GetNumberOfClusters();
   fIndex[n]=index;
   SetNumberOfClusters(n+1);
@@ -411,124 +423,45 @@ Int_t AliITStrackV2::Update(const AliCluster* c, Double_t chi2, UInt_t index) {
   return 1;
 }
 
-
-//____________________________________________________________________________
-Int_t AliITStrackV2::Update(const Double_t* m, Double_t chi2, UInt_t index) {
+Int_t AliITStrackV2::Invariant() const {
   //------------------------------------------------------------------
-  //This function updates track parameters with a vertex constraint
+  // This function is for debugging purpose only
   //------------------------------------------------------------------
-  Double_t p0=fP0,p1=fP1,p2=fP2,p3=fP3,p4=fP4;
-  Double_t c00=fC00;
-  Double_t c10=fC10, c11=fC11;
-  Double_t c20=fC20, c21=fC21, c22=fC22;
-  Double_t c30=fC30, c31=fC31, c32=fC32, c33=fC33;
-  Double_t c40=fC40, c41=fC41, c42=fC42, c43=fC43, c44=fC44;
-
-
-  TVectorD x(5); x(0)=fP0; x(1)=fP1; x(2)=fP2; x(3)=fP3; x(4)=fP4;
-  TMatrixD C(5,5);
-  C(0,0)=fC00; 
-  C(1,0)=fC10; C(1,1)=fC11; 
-  C(2,0)=fC20; C(2,1)=fC21; C(2,2)=fC22;
-  C(3,0)=fC30; C(3,1)=fC31; C(3,2)=fC32; C(3,3)=fC33;
-  C(4,0)=fC40; C(4,1)=fC41; C(4,2)=fC42; C(4,3)=fC43; C(4,4)=fC44;
-
-  C(0,1)=C(1,0);
-  C(0,2)=C(2,0); C(1,2)=C(2,1);
-  C(0,3)=C(3,0); C(1,3)=C(3,1); C(2,3)=C(3,2);
-  C(0,4)=C(4,0); C(1,4)=C(4,1); C(2,4)=C(4,2); C(3,4)=C(4,3);
-
-  TMatrixD H(4,5); H.UnitMatrix();
-  TMatrixD Ht(TMatrixD::kTransposed,H);
-  TVectorD mm(4); mm(0)=m[0]; mm(1)=m[1]; mm(2)=m[2]; mm(3)=m[3];
-  TMatrixD V(4,4); 
-  V(0,0)=m[4 ]; V(0,1)=m[5 ]; V(0,2)=m[6 ]; V(0,3)=m[7 ];
-  V(1,0)=m[8 ]; V(1,1)=m[9 ]; V(1,2)=m[10]; V(1,3)=m[11];
-  V(2,0)=m[12]; V(2,1)=m[13]; V(2,2)=m[14]; V(2,3)=m[15];
-  V(3,0)=m[16]; V(3,1)=m[17]; V(3,2)=m[18]; V(3,3)=m[19];
-
-  TMatrixD tmp(H,TMatrixD::kMult,C);
-  TMatrixD R(tmp,TMatrixD::kMult,Ht); R+=V;
-
-  R.Invert();
-  
-  TMatrixD K(C,TMatrixD::kMult,Ht); K*=R;
+  Int_t n=GetNumberOfClusters();
   
-  TVectorD savex=x;
-  x*=H; x-=mm; x*=-1; x*=K; x+=savex;
-
-  TMatrixD saveC=C;
-  C.Mult(K,tmp); C-=saveC; C*=-1;
-
-  fP0=x(0); fP1=x(1); fP2=x(2); fP3=x(3); fP4=x(4);
-  fC00=C(0,0); 
-  fC10=C(1,0); fC11=C(1,1); 
-  fC20=C(2,0); fC21=C(2,1); fC22=C(2,2);
-  fC30=C(3,0); fC31=C(3,1); fC32=C(3,2); fC33=C(3,3);
-  fC40=C(4,0); fC41=C(4,1); fC42=C(4,2); fC43=C(4,3); fC44=C(4,4);
-
-
-  if (!Invariant()) {
-     fP0=p0; fP1=p1; fP2=p2; fP3=p3; fP4=p4;
-     fC00=c00;
-     fC10=c10; fC11=c11;
-     fC20=c20; fC21=c21; fC22=c22;
-     fC30=c30; fC31=c31; fC32=c32; fC33=c33;
-     fC40=c40; fC41=c41; fC42=c42; fC43=c43; fC44=c44;
+  if (TMath::Abs(fP2)>=0.9999){
+     if (n>kWARN) Warning("Invariant","fP2=%f\n",fP2);
+     return 0;
+  }
+  if (fC00<=0 || fC00>9.) {
+     if (n>kWARN) Warning("Invariant","fC00=%f\n",fC00); 
+     return 0;
+  }
+  if (fC11<=0 || fC11>9.) {
+     if (n>kWARN) Warning("Invariant","fC11=%f\n",fC11); 
+     return 0;
+  }
+  if (fC22<=0 || fC22>1.) {
+     if (n>kWARN) Warning("Invariant","fC22=%f\n",fC22); 
+     return 0;
+  }
+  if (fC33<=0 || fC33>1.) {
+     if (n>kWARN) Warning("Invariant","fC33=%f\n",fC33); 
+     return 0;
+  }
+  if (fC44<=0 || fC44>6e-5) {
+     if (n>kWARN) Warning("Invariant","fC44=%f\n",fC44);
      return 0;
   }
-
-  Int_t n=GetNumberOfClusters();
-  fIndex[n]=index;
-  SetNumberOfClusters(n+1);
-  SetChi2(GetChi2()+chi2);
-
   return 1;
 }
 
-Int_t AliITStrackV2::Invariant() const {
-  //------------------------------------------------------------------
-  // This function is for debugging purpose only
-  //------------------------------------------------------------------
-  //if (TMath::Abs(fP1)>11.5)
-  //if (fP1*fP4<0) {cout<<"fP1*fP4="<<fP1*fP4<<' '<<fP1<<endl; return 0;}
-  if (TMath::Abs(fP2)>=1) {cout<<"fP2="<<fP2<<endl; return 0;}
-
-  if (fC00<=0) {cout<<"fC00="<<fC00<<endl; return 0;}
-  if (fC11<=0) {cout<<"fC11="<<fC11<<endl; return 0;}
-  if (fC22<=0) {cout<<"fC22="<<fC22<<endl; return 0;}
-  if (fC33<=0) {cout<<"fC33="<<fC33<<endl; return 0;}
-  if (fC44<=0) {cout<<"fC44="<<fC44<<endl; return 0;}
-
-   TMatrixD m(5,5);
-   m(0,0)=fC00; 
-   m(1,0)=fC10; m(1,1)=fC11; 
-   m(2,0)=fC20; m(2,1)=fC21; m(2,2)=fC22;
-   m(3,0)=fC30; m(3,1)=fC31; m(3,2)=fC32; m(3,3)=fC33;
-   m(4,0)=fC40; m(4,1)=fC41; m(4,2)=fC42; m(4,3)=fC43; m(4,4)=fC44;
-
-   m(0,1)=m(1,0);
-   m(0,2)=m(2,0); m(1,2)=m(2,1);
-   m(0,3)=m(3,0); m(1,3)=m(3,1); m(2,3)=m(3,2);
-   m(0,4)=m(4,0); m(1,4)=m(4,1); m(2,4)=m(4,2); m(3,4)=m(4,3);
-   /*
-   Double_t det=m.Determinant(); 
-
-   if (det <= 0) {
-       cout<<" bad determinant "<<det<<endl;
-       m.Print(); 
-       return 0;
-   }
-   */
-   return 1;
-}
-
 //____________________________________________________________________________
-Int_t AliITStrackV2::Propagate(Double_t alp, Double_t xk,
-Double_t x0,Double_t rho,Double_t pm) {
+Int_t AliITStrackV2::Propagate(Double_t alp,Double_t xk) {
   //------------------------------------------------------------------
   //This function propagates a track
   //------------------------------------------------------------------
+  Double_t alpha=fAlpha, x=fX;
   Double_t p0=fP0,p1=fP1,p2=fP2,p3=fP3,p4=fP4;
   Double_t c00=fC00;
   Double_t c10=fC10, c11=fC11;
@@ -536,106 +469,81 @@ Double_t x0,Double_t rho,Double_t pm) {
   Double_t c30=fC30, c31=fC31, c32=fC32, c33=fC33;
   Double_t c40=fC40, c41=fC41, c42=fC42, c43=fC43, c44=fC44;
 
+  if      (alp < -TMath::Pi()) alp += 2*TMath::Pi();
+  else if (alp >= TMath::Pi()) alp -= 2*TMath::Pi();
+  Double_t ca=TMath::Cos(alp-fAlpha), sa=TMath::Sin(alp-fAlpha);
+  Double_t sf=fP2, cf=TMath::Sqrt(1.- fP2*fP2);
 
-  Double_t dalp=alp-fAlpha;
-
-  Double_t ca=TMath::Cos(dalp), sa=TMath::Sin(dalp);
-  Double_t sf=fP2, cf=TMath::Sqrt(1.- fP2*fP2);  
-
-  Double_t pp2=fP2*ca - cf*sa;
-  if (TMath::Abs(pp2) >= 0.99999) {
-     Int_t n=GetNumberOfClusters();
-     if (n>kWARN) cerr<<n<<" AliITStrackV2 warning: Rotation failed !\n";
-     return 0;
-  }
-
+  TMatrixD *T=0;
+  // **** rotation **********************
+  {
   fAlpha = alp;
-  if      (fAlpha < -TMath::Pi()) fAlpha += 2*TMath::Pi();
-  else if (fAlpha >= TMath::Pi()) fAlpha -= 2*TMath::Pi();
-  
-  Double_t x1=fX, y1=fP0;
-
-  fX = x1*ca + y1*sa;
-  fP0=-x1*sa + y1*ca;
-  fP2 = pp2;
+  fX =  x*ca + p0*sa;
+  fP0= -x*sa + p0*ca;
+  fP2=  sf*ca - cf*sa;
+
+  static TMatrixD C(5,5); 
+  C(0,0)=c00;
+  C(1,0)=c10; C(1,1)=c11;
+  C(2,0)=c20; C(2,1)=c21; C(2,2)=c22;
+  C(3,0)=c30; C(3,1)=c31; C(3,2)=c32; C(3,3)=c33;
+  C(4,0)=c40; C(4,1)=c41; C(4,2)=c42; C(4,3)=c43; C(4,4)=c44;
+  C(0,1)=C(1,0);
+  C(0,2)=C(2,0); C(1,2)=C(2,1);
+  C(0,3)=C(3,0); C(1,3)=C(3,1); C(2,3)=C(3,2);
+  C(0,4)=C(4,0); C(1,4)=C(4,1); C(2,4)=C(4,2); C(3,4)=C(4,3);
 
-  cf=ca + sf*sa/cf;
+  
+  static TMatrixD F(6,5);
+  F(0,0)=sa; 
+  F(1,0)=ca;
+  F(2,1)=F(4,3)=F(5,4)=1; 
+  F(3,2)=ca + sf/cf*sa;
 
-  if (!Invariant()) {cout<<dalp<<" Rotate !\n"; return 0;}
+  //TMatrixD tmp(C,TMatrixD::kMult,TMatrixD(TMatrixD::kTransposed, F)); 
+  
+  static TMatrixD Ft(5,6);
+  Ft(0,0)=sa; 
+  Ft(0,1)=ca;
+  Ft(1,2)=Ft(3,4)=Ft(4,5)=1; 
+  Ft(2,3)=ca + sf/cf*sa;
+
+  TMatrixD tmp(C,TMatrixD::kMult,Ft); 
+  T=new TMatrixD(F,TMatrixD::kMult,tmp); 
+  }
 
-  x1=fX; Double_t x2=xk, dx=x2-x1;
+  // **** translation ******************
+  {
+  Double_t dx=xk-fX;
   Double_t f1=fP2, f2=f1 + fP4*dx;
-  if (TMath::Abs(f2) >= 0.99999) {
+  if (TMath::Abs(f2) >= 0.9999) {
     Int_t n=GetNumberOfClusters();
-    if (n>kWARN) cerr<<n<<" AliITStrackV2 warning: Propagation failed !\n";
+    if (n>kWARN) 
+       Warning("Propagate","Propagation failed (%d) !\n",n);
     return 0;
   }
-
-  Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
+  Double_t r1=TMath::Sqrt(1.- f1*f1), r2=TMath::Sqrt(1.- f2*f2);
   
+  fX=xk;
   fP0 += dx*(f1+f2)/(r1+r2);
   fP1 += dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
   fP2 += dx*fP4;
 
-  //f = F - 1
-  Double_t f02=    dx/(r1*r1*r1);
-  Double_t f04=0.5*dx*dx/(r1*r1*r1);
-  Double_t f12=    dx*fP3*f1/(r1*r1*r1);
-  Double_t f14=0.5*dx*dx*fP3*f1/(r1*r1*r1);
-  Double_t f13=    dx/r1;
-  Double_t f24=    dx; 
-  /*
-  //b = C*ft
-  Double_t b00=f02*fC20 + f03*fC30, b01=f12*fC20 + f13*fC30 + f14*fC40;
-  Double_t b02=f23*fC30;
-  Double_t b10=f02*fC21 + f03*fC31, b11=f12*fC21 + f13*fC31 + f14*fC41;
-  Double_t b12=f23*fC31;
-  Double_t b20=f02*fC22 + f03*fC32, b21=f12*fC22 + f13*fC32 + f14*fC42;
-  Double_t b22=f23*fC32;
-  Double_t b30=f02*fC32 + f03*fC33, b31=f12*fC32 + f13*fC33 + f14*fC43;
-  Double_t b32=f23*fC33;
-  Double_t b40=f02*fC42 + f03*fC43, b41=f12*fC42 + f13*fC43 + f14*fC44;
-  Double_t b42=f23*fC43;
-  
-  //a = f*b = f*C*ft
-  Double_t a00=f02*b20+f03*b30,a01=f02*b21+f03*b31,a02=f02*b22+f03*b32;
-  Double_t a11=f12*b21+f13*b31+f14*b41,a12=f12*b22+f13*b32+f14*b42;
-  Double_t a22=f23*b32;
-
-  //F*C*Ft = C + (b + bt + a)
-  fC00 += b00 + b00 + a00;
-  fC10 += b10 + b01 + a01; 
-  fC20 += b20 + b02 + a02;
-  fC30 += b30;
-  fC40 += b40;
-  fC11 += b11 + b11 + a11;
-  fC21 += b21 + b12 + a12;
-  fC31 += b31; 
-  fC41 += b41;
-  fC22 += b22 + b22 + a22;
-  fC32 += b32;
-  fC42 += b42;
-*/
-
- TMatrixD F(5,5); F.UnitMatrix();
- F(0,0)=-(f1+f2)/(r1+r2)*sa + ca; F(0,2)=f02*cf; F(0,4)=f04;
- F(1,0)=-(f1+f2)/(f1*r2 + f2*r1)*fP3*sa; F(1,2)=f12*cf; F(1,4)=f14; F(1,3)=f13;
- F(2,0)=-fP4*sa; F(2,2)=cf; F(2,4)=f24;
-
-  TMatrixD C(5,5);
-  C(0,0)=fC00; 
-  C(1,0)=fC10; C(1,1)=fC11; 
-  C(2,0)=fC20; C(2,1)=fC21; C(2,2)=fC22;
-  C(3,0)=fC30; C(3,1)=fC31; C(3,2)=fC32; C(3,3)=fC33;
-  C(4,0)=fC40; C(4,1)=fC41; C(4,2)=fC42; C(4,3)=fC43; C(4,4)=fC44;
-
-  C(0,1)=C(1,0);
-  C(0,2)=C(2,0); C(1,2)=C(2,1);
-  C(0,3)=C(3,0); C(1,3)=C(3,1); C(2,3)=C(3,2);
-  C(0,4)=C(4,0); C(1,4)=C(4,1); C(2,4)=C(4,2); C(3,4)=C(4,3);
-
-  TMatrixD tmp(C,TMatrixD::kMult,TMatrixD(TMatrixD::kTransposed, F));
-  C.Mult(F,tmp);
+  static TMatrixD F(5,6);
+  F(0,1)=F(1,2)=F(2,3)=F(3,4)=F(4,5)=1; 
+  F(0,3)=dx/(r1+r2)*(2+(f1+f2)*(f2/r2+f1/r1)/(r1+r2)); 
+  F(0,5)=dx*dx/(r1+r2)*(1+(f1+f2)*f2/(r1+r2));
+  F(1,3)=dx*fP3/(f1*r2 + f2*r1)*(2-(f1+f2)*(r2-f1*f2/r2+r1-f2*f1/r1)/(f1*r2 + f2*r1));
+  F(1,4)=dx*(f1+f2)/(f1*r2 + f2*r1);
+  F(1,5)=dx*dx*fP3/(f1*r2 + f2*r1)*(1-(f1+f2)*(-f1*f2/r2+r1)/(f1*r2 + f2*r1));
+  F(2,5)=dx;
+  F(0,0)=-1/(r1+r2)*((f1+f2)+dx*fP4*(1+(f1+f2)/(r1+r2)*f2/r2));
+  F(1,0)=-fP3/(f1*r2 + f2*r1)*((f1+f2)+dx*fP4*(1+(f1+f2)/(f1*r2 + f2*r1)*(f1*f2/r2-r1)));
+  F(2,0)=-fP4;
+
+  TMatrixD tmp(*T,TMatrixD::kMult,TMatrixD(TMatrixD::kTransposed, F)); 
+  delete T;
+  TMatrixD C(F,TMatrixD::kMult,tmp);
 
   fC00=C(0,0); 
   fC10=C(1,0); fC11=C(1,1); 
@@ -643,29 +551,9 @@ Double_t x0,Double_t rho,Double_t pm) {
   fC30=C(3,0); fC31=C(3,1); fC32=C(3,2); fC33=C(3,3);
   fC40=C(4,0); fC41=C(4,1); fC42=C(4,2); fC43=C(4,3); fC44=C(4,4);
 
-  pp2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
-  Double_t beta2=pp2/(pp2 + pm*pm);
-
-  //Multiple scattering******************
-  //x0=0.;
-  if (x0!=0.) {
-     x0*=TMath::Sqrt((1.+ fP3*fP3)/(1.- fP2*fP2));
-     Double_t theta2=14.1*14.1/(beta2*pp2*1e6)*x0;
-     fC22 += theta2*(1.- fP2*fP2)*(1. + fP3*fP3);
-     fC33 += theta2*(1. + fP3*fP3)*(1. + fP3*fP3);
-     fC43 += theta2*fP3*fP4*(1. + fP3*fP3);
-     fC44 += theta2*fP3*fP4*fP3*fP4;
-  }
-
-  //Energy losses************************
-  if (rho!=0.) {  
-     rho*=TMath::Sqrt((1.+ fP3*fP3)/(1.- fP2*fP2));
-     Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*rho;
-     if (x1 < x2) dE=-dE;
-     fP4*=(1.- sqrt(pp2+pm*pm)/pp2*dE);
-  }
-
   if (!Invariant()) {
+     fAlpha=alpha; 
+     fX=x; 
      fP0=p0; fP1=p1; fP2=p2; fP3=p3; fP4=p4;
      fC00=c00;
      fC10=c10; fC11=c11;
@@ -674,127 +562,135 @@ Double_t x0,Double_t rho,Double_t pm) {
      fC40=c40; fC41=c41; fC42=c42; fC43=c43; fC44=c44;
      return 0;
   }
-
-  fX=x2;
+  }
 
   return 1;
 }
 
-Double_t AliITStrackV2::GetD() const {
+Double_t AliITStrackV2::GetD(Double_t x, Double_t y) const {
   //------------------------------------------------------------------
-  //This function calculates the transverse impact parameter
+  // This function calculates the transverse impact parameter
+  // with respect to a point with global coordinates (x,y)
   //------------------------------------------------------------------
-  Double_t sn=fP4*fX - fP2, cs=fP4*fP0 + TMath::Sqrt(1.- fP2*fP2);
-  Double_t a=2*(fX*fP2 - fP0*TMath::Sqrt(1.- fP2*fP2))-fP4*(fX*fX + fP0*fP0);
+  Double_t xt=fX, yt=fP0;
+
+  Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha);
+  Double_t a = x*cs + y*sn;
+  y = -x*sn + y*cs; x=a;
+  xt-=x; yt-=y;
+
+  sn=fP4*xt - fP2; cs=fP4*yt + TMath::Sqrt(1.- fP2*fP2);
+  a=2*(xt*fP2 - yt*TMath::Sqrt(1.- fP2*fP2))-fP4*(xt*xt + yt*yt);
   if (fP4<0) a=-a;
   return a/(1 + TMath::Sqrt(sn*sn + cs*cs));
-} 
+}
+
+Double_t AliITStrackV2::GetZat(Double_t x) const {
+  //------------------------------------------------------------------
+  // This function calculates the z at given x point - in current coordinate system
+  //------------------------------------------------------------------
+  Double_t x1=fX, x2=x, dx=x2-x1;
+  //
+  Double_t f1=fP2, f2=f1 + fP4*dx;
+  if (TMath::Abs(f2) >= 0.9999) {
+    return 10000000;
+  }
+  Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
+  Double_t z =  fP1 + dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
+  return z;
+}
+
 
 
-Int_t AliITStrackV2::Improve(Double_t x0,Double_t yv,Double_t zv) {
+
+Int_t AliITStrackV2::Improve(Double_t x0,Double_t xyz[3],Double_t ers[3]) {
   //------------------------------------------------------------------
   //This function improves angular track parameters  
   //------------------------------------------------------------------
+  Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
+  //Double_t xv = xyz[0]*cs + xyz[1]*sn; // vertex
+    Double_t yv =-xyz[0]*sn + xyz[1]*cs; // in the
+    Double_t zv = xyz[2];                // local frame
   Double_t dy=fP0-yv, dz=fP1-zv;
   Double_t r2=fX*fX+dy*dy;
   Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
-  Double_t beta2=p2/(p2 + 0.14*0.14);
+  Double_t beta2=p2/(p2 + GetMass()*GetMass());
   x0*=TMath::Sqrt((1.+ GetTgl()*GetTgl())/(1.- GetSnp()*GetSnp()));
   Double_t theta2=14.1*14.1/(beta2*p2*1e6)*x0;
-
-  Double_t par=0.5*(fP4*fX + dy*TMath::Sqrt(4/r2-fP4*fP4));
-  Double_t sigma2 = theta2*(1.- GetSnp()*GetSnp())*(1. + GetTgl()*GetTgl());
-  sigma2 += fC00/r2*(1.- dy*dy/r2)*(1.- dy*dy/r2);
-  sigma2 += kSigmaYV*kSigmaYV/r2;
-  sigma2 += 0.25*fC44*fX*fX;
-  Double_t eps2=sigma2/(fC22+sigma2), eps=TMath::Sqrt(eps2);
-  if (10*r2*fC44<fC22) {
-     fP2 = eps2*fP2 + (1-eps2)*par;
-     fC22*=eps2; fC21*=eps; fC20*=eps; fC32*=eps; fC42*=eps;
+  //Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*x0*9.36*2.33;
+  {
+  Double_t parp=0.5*(fP4*fX + dy*TMath::Sqrt(4/r2-fP4*fP4));
+  Double_t sigma2p = theta2*(1.- GetSnp()*GetSnp())*(1. + GetTgl()*GetTgl());
+  sigma2p += fC00/r2*(1.- dy*dy/r2)*(1.- dy*dy/r2);
+  sigma2p += ers[1]*ers[1]/r2;
+  sigma2p += 0.25*fC44*fX*fX;
+  Double_t eps2p=sigma2p/(fC22+sigma2p);
+  fP0 += fC20/(fC22+sigma2p)*(parp-fP2);
+  fP2 = eps2p*fP2 + (1-eps2p)*parp;
+  fC22 *= eps2p;
+  fC20 *= eps2p;
+  }
+  {
+  Double_t parl=0.5*fP4*dz/TMath::ASin(0.5*fP4*TMath::Sqrt(r2));
+  Double_t sigma2l=theta2;
+  sigma2l += fC11/r2+fC00*dy*dy*dz*dz/(r2*r2*r2);
+  sigma2l += ers[2]*ers[2]/r2;
+  Double_t eps2l=sigma2l/(fC33+sigma2l);
+  fP1 += fC31/(fC33+sigma2l)*(parl-fP3);
+  fP4 += fC43/(fC33+sigma2l)*(parl-fP3);
+  fP3 = eps2l*fP3 + (1-eps2l)*parl;
+  fC33 *= eps2l; fC43 *= eps2l; 
+  fC31 *= eps2l; 
   }
-
-  par=0.5*fP4*dz/TMath::ASin(0.5*fP4*TMath::Sqrt(r2));
-  sigma2=theta2;
-  sigma2 += fC11/r2+fC00*dy*dy*dz*dz/(r2*r2*r2);
-  sigma2 += kSigmaZV*kSigmaZV/r2;
-  eps2=sigma2/(fC33+sigma2); eps=TMath::Sqrt(eps2);
-  Double_t tgl=fP3;
-  fP3 = eps2*fP3 + (1-eps2)*par;
-  fC33*=eps2; fC32*=eps; fC31*=eps; fC30*=eps; fC43*=eps;
-
-  eps=TMath::Sqrt((1+fP3*fP3)/(1+tgl*tgl));
-  fP4*=eps;
-  fC44*=eps*eps; fC43*=eps;fC42*=eps; fC41*=eps; fC40*=eps;
-
   if (!Invariant()) return 0;
   return 1;
 } 
 
-/*
-Int_t AliITStrackV2::Improve(Double_t x0,Double_t xv,Double_t yv) {
+void AliITStrackV2::ResetCovariance() {
   //------------------------------------------------------------------
-  //This function improves angular track parameters  
+  //This function makes a track forget its history :)  
   //------------------------------------------------------------------
-  TMatrixD I(5,5);
-  TVectorD v(5); v(0)=fP0; v(1)=fP1; v(2)=fP2; v(3)=fP3; v(4)=fP4;
-
-  Double_t r2=fX*fX+fP0*fP0;
-  Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
-  Double_t beta2=p2/(p2 + 0.14*0.14);
-  x0*=TMath::Sqrt((1.+ GetTgl()*GetTgl())/(1.- GetSnp()*GetSnp()));
-  Double_t theta2=14.1*14.1/(beta2*p2*1e6)*x0;
-
-  v(2)=0.5*(fP4*fX + fP0*TMath::Sqrt(4/r2-fP4*fP4));
-  Double_t sigma2 = theta2*(1.- GetSnp()*GetSnp())*(1. + GetTgl()*GetTgl());
-  sigma2 += fC00/r2*(1.- fP0*fP0/r2)*(1.- fP0*fP0/r2);
-  sigma2 += kSigmaYV*kSigmaYV/r2;
-  I(2,2)=1/sigma2;
-
-  v(3)=0.5*fP4*fP1/TMath::ASin(0.5*fP4*TMath::Sqrt(r2));
-  sigma2=theta2;
-  sigma2 += fC11/r2+fC00*fP0*fP0*fP1*fP1/(r2*r2*r2);
-  sigma2 += kSigmaZV*kSigmaZV/r2;
-  I(3,3)=1/sigma2;
-
-  Double_t tgl=fP3;
-
-  TVectorD x(5); x(0)=fP0; x(1)=fP1; x(2)=fP2; x(3)=fP3; x(4)=fP4;
-  TMatrixD C(5,5);
-  C(0,0)=fC00; 
-  C(1,0)=fC10; C(1,1)=fC11; 
-  C(2,0)=fC20; C(2,1)=fC21; C(2,2)=fC22;
-  C(3,0)=fC30; C(3,1)=fC31; C(3,2)=fC32; C(3,3)=fC33;
-  C(4,0)=fC40; C(4,1)=fC41; C(4,2)=fC42; C(4,3)=fC43; C(4,4)=fC44;
-
-  C(0,1)=C(1,0);
-  C(0,2)=C(2,0); C(1,2)=C(2,1);
-  C(0,3)=C(3,0); C(1,3)=C(3,1); C(2,3)=C(3,2);
-  C(0,4)=C(4,0); C(1,4)=C(4,1); C(2,4)=C(4,2); C(3,4)=C(4,3);
-
-  TMatrixD tmp(I,TMatrixD::kMult,C),U(5,5); U.UnitMatrix();
-  U+=tmp;
-  U.Invert();
-  TMatrixD W1(U);
-  TMatrixD W2(tmp,TMatrixD::kMult,W1);
-
-  v*=W2; x*=W1; x+=v;
-
-  C*=W1;
 
+  fC00*=10.;
+  fC10=0.;  fC11*=10.;
+  fC20=0.;  fC21=0.;  fC22*=10.;
+  fC30=0.;  fC31=0.;  fC32=0.;  fC33*=10.;
+  fC40=0.;  fC41=0.;  fC42=0.;  fC43=0.;  fC44*=10.;
 
-  fP0=x(0); fP1=x(1); fP2=x(2); fP3=x(3); fP4=x(4);
-  fC00=C(0,0); 
-  fC10=C(1,0); fC11=C(1,1); 
-  fC20=C(2,0); fC21=C(2,1); fC22=C(2,2);
-  fC30=C(3,0); fC31=C(3,1); fC32=C(3,2); fC33=C(3,3);
-  fC40=C(4,0); fC41=C(4,1); fC42=C(4,2); fC43=C(4,3); fC44=C(4,4);
-
-  eps=TMath::Sqrt((1+fP3*fP3)/(1+tgl*tgl));
-  fP4*=eps;
-  fC44*=eps*eps; fC43*=eps;fC42*=eps; fC41*=eps; fC40*=eps;
+}
 
-  if (!Invariant()) return 0;
-  return 1;
-} 
-*/
+void AliITStrackV2::CookdEdx(Double_t low, Double_t up) {
+  //-----------------------------------------------------------------
+  // This function calculates dE/dX within the "low" and "up" cuts.
+  // Origin: Boris Batyunya, JINR, Boris.Batiounia@cern.ch 
+  //-----------------------------------------------------------------
+  // The clusters order is: SSD-2, SSD-1, SDD-2, SDD-1, SPD-2, SPD-1
+
+  Int_t i;
+  Int_t nc=0;
+  for (i=0; i<GetNumberOfClusters(); i++) {
+    Int_t idx=GetClusterIndex(i);
+    idx=(idx&0xf0000000)>>28;
+    if (idx>1) nc++; // Take only SSD and SDD
+  }
 
+  Int_t swap;//stupid sorting
+  do {
+    swap=0;
+    for (i=0; i<nc-1; i++) {
+      if (fdEdxSample[i]<=fdEdxSample[i+1]) continue;
+      Float_t tmp=fdEdxSample[i];
+      fdEdxSample[i]=fdEdxSample[i+1]; fdEdxSample[i+1]=tmp;
+      swap++;
+    }
+  } while (swap);
+
+  Int_t nl=Int_t(low*nc), nu=Int_t(up*nc); //b.b. to take two lowest dEdX
+                                           // values from four ones choose
+                                           // nu=2
+  Float_t dedx=0;
+  for (i=nl; i<nu; i++) dedx += fdEdxSample[i];
+  if (nu-nl>0) dedx /= (nu-nl);
+
+  SetdEdx(dedx);
+}