X-Git-Url: http://git.uio.no/git/?a=blobdiff_plain;f=RALICE%2FAliTrack.cxx;h=e260e808b231cefbd4a2aa1c6a946cb6a8ee1264;hb=a05adbe9a6af7c1a8fe38ba2adc85d3c57fedabe;hp=672059497a026036d0b54edbeb7956c1ba3a6152;hpb=1f241680a2749a27e9674b93ebb6e7d4f60d4701;p=u%2Fmrichter%2FAliRoot.git

diff --git a/RALICE/AliTrack.cxx b/RALICE/AliTrack.cxx
index 672059497a0..e260e808b23 100644
--- a/RALICE/AliTrack.cxx
+++ b/RALICE/AliTrack.cxx
@@ -83,14 +83,24 @@
 // trec.SetBeginPoint(begin);
 // trec.SetEndPoint(end);
 // 
-// Note : All quantities are in GeV, GeV/c or GeV/c**2
+// Note : By default all quantities are in GeV, GeV/c or GeV/c**2
+//        but the user can indicate the usage of a different scale
+//        for the energy-momentum units via the SetEscale() memberfunction.
+//        The actual energy-momentum unit scale can be obtained via the
+//        GetEscale() memberfunction.
 //
 //--- Author: Nick van Eijndhoven 10-jul-1997 UU-SAP Utrecht
 //- Modified: NvE $Date$ UU-SAP Utrecht
 ///////////////////////////////////////////////////////////////////////////
 
-#include "AliTrack.h"
 #include "Riostream.h"
+#include "TObjArray.h"
+
+#include "AliBoost.h"
+#include "AliPositionObj.h"
+#include "AliSignal.h"
+#include "AliTimestamp.h"
+#include "AliTrack.h"
  
 ClassImp(AliTrack) // Class implementation to enable ROOT I/O
  
@@ -118,18 +128,19 @@ void AliTrack::Init()
  fParent=0;
  fFit=0;
  fTstamp=0;
+ fEscale=1;
 }
 ///////////////////////////////////////////////////////////////////////////
 AliTrack::~AliTrack()
 {
 // Destructor to delete memory allocated for decay tracks array.
-// This destructor automatically cleares the pointer of this AliTrack
-// from all the link slots of the related AliSignal objects.
+// This destructor automatically cleares all references to this AliTrack
+// from all the related AliSignal objects.
  Int_t nsig=GetNsignals();
  for (Int_t i=1; i<=nsig; i++)
  {
   AliSignal* s=GetSignal(i);
-  if (s) s->ResetLinks(this);
+  if (s) s->RemoveTrack(*this,0);
  }
  
  if (fDecays)
@@ -139,7 +150,6 @@ AliTrack::~AliTrack()
  }
  if (fSignals)
  {
-  fSignals->Clear();
   delete fSignals;
   fSignals=0;
  }
@@ -212,8 +222,7 @@ AliTrack::AliTrack(const AliTrack& t) : TNamed(t),Ali4Vector(t)
  if (t.fFit) fFit=t.fFit->Clone();
  if (t.fTstamp) fTstamp=new AliTimestamp(*(t.fTstamp));
  fUserId=t.fUserId;
- fChi2=t.fChi2;
- fNdf=t.fNdf;
+ fEscale=t.fEscale;
  fCode=t.fCode;
  fParent=t.fParent;
 
@@ -256,9 +265,8 @@ AliTrack::AliTrack(const AliTrack& t) : TNamed(t),Ali4Vector(t)
 void AliTrack::Reset()
 {
 // Reset all variables to 0 and delete all auto-generated decay tracks.
+// Note : The scale for the energy/momentum units will not be changed.
  fQ=0;
- fChi2=0;
- fNdf=0;
  fUserId=0;
  fCode=0;
  fProb=0;
@@ -272,7 +280,6 @@ void AliTrack::Reset()
  }
  if (fSignals)
  {
-  fSignals->Clear();
   delete fSignals;
   fSignals=0;
  }
@@ -340,10 +347,10 @@ void AliTrack::Set3Momentum(Ali3Vector& p)
 void AliTrack::Set4Momentum(Ali4Vector& p)
 {
 // Set the track parameters according to the 4-momentum p
- Double_t E=p.GetScalar();
+ Double_t eE=p.GetScalar();
  Double_t dE=p.GetResultError();
  Ali3Vector pv=p.Get3Vector();
- SetVector(E,pv);
+ SetVector(eE,pv);
  SetScalarError(dE);
 }
 ///////////////////////////////////////////////////////////////////////////
@@ -387,7 +394,7 @@ void AliTrack::Data(TString f,TString u)
       << " m : " << m << " dm : " << dm << " Charge : " << fQ
       << " p : " << GetMomentum() << endl;
  cout << " Nhypotheses : " << GetNhypotheses() << " Ndecay-tracks : " << GetNdecay()
-      << " Nsignals : " << GetNsignals() << endl;
+      << " Nsignals : " << GetNsignals() << " Energy scale : " << fEscale << " GeV" << endl;
  if (fParent)
  {
   cout << " Parent track Id : " << fParent->GetId() << " Code : " << fParent->GetParticleCode()
@@ -419,6 +426,9 @@ void AliTrack::List(TString f,TString u)
 // The defaults are f="car" and u="rad".
 
  Data(f,u); // Information of the current track
+ if (fBegin) { cout << " Begin-point :"; fBegin->Data(f,u); }
+ if (fEnd)   { cout << " End-point   :"; fEnd->Data(f,u); }
+ if (fRef)   { cout << " Ref-point   :"; fRef->Data(f,u); }
 
  // Decay products of this track
  AliTrack* td; 
@@ -449,9 +459,9 @@ void AliTrack::ListAll(TString f,TString u)
 // The defaults are f="car" and u="rad".
 
  Data(f,u); // Information of the current track
- if (fBegin) { cout << " Begin-point :"; fBegin->Data(f); }
- if (fEnd)   { cout << " End-point   :"; fEnd->Data(f); }
- if (fRef)   { cout << " Ref-point   :"; fRef->Data(f); }
+ if (fBegin) { cout << " Begin-point :"; fBegin->Data(f,u); }
+ if (fEnd)   { cout << " End-point   :"; fEnd->Data(f,u); }
+ if (fRef)   { cout << " Ref-point   :"; fRef->Data(f,u); }
 
  Int_t nhyp=GetNhypotheses();
  if (nhyp)
@@ -494,7 +504,7 @@ void AliTrack::ListAll(TString f,TString u)
  Dumps(t,1,f,u); // Information of all decay products
 }
 //////////////////////////////////////////////////////////////////////////
-void AliTrack::Dumps(AliTrack* t,Int_t n,TString f,TString u)
+void AliTrack::Dumps(const AliTrack* t,Int_t n,TString f,TString u)
 {
 // Recursively provide the info of all decay levels of this track
  AliTrack* td; 
@@ -538,27 +548,53 @@ void AliTrack::Dumps(AliTrack* t,Int_t n,TString f,TString u)
  }
 } 
 //////////////////////////////////////////////////////////////////////////
-Double_t AliTrack::GetMomentum()
+Double_t AliTrack::GetMomentum(Float_t scale)
 {
 // Provide the value of the track 3-momentum.
+// By default the momentum is returned in the units as it was stored in the track
+// structure. However, the user can select a different momentum unit scale by
+// specification of the scale parameter.
+// The convention is that scale=1 corresponds to GeV/c, so specification
+// of scale=0.001 will provide the momentum in MeV/c.
 // The error can be obtained by invoking GetResultError() after
 // invokation of GetMomentum().
+
  Double_t norm=fV.GetNorm();
  fDresult=fV.GetResultError();
+ if (scale>0)
+ {
+  norm*=fEscale/scale;
+  fDresult*=fEscale/scale;
+ }
  return norm;
 }
 ///////////////////////////////////////////////////////////////////////////
-Ali3Vector AliTrack::Get3Momentum() const
+Ali3Vector AliTrack::Get3Momentum(Float_t scale) const
 {
-// Provide the track 3-momentum
- return (Ali3Vector)Get3Vector();
+// Provide the track 3-momentum.
+// By default the components of the 3-momentum are returned in the units
+// as they were stored in the track structure.
+// However, the user can select a different momentum unit scale for the
+// components by specification of the scale parameter.
+// The convention is that scale=1 corresponds to GeV/c, so specification
+// of scale=0.001 will provide the 3-momentum in MeV/c.
+
+ Ali3Vector p=Get3Vector();
+ if (scale>0) p*=fEscale/scale;
+ return p;
 }
 ///////////////////////////////////////////////////////////////////////////
-Double_t AliTrack::GetMass()
+Double_t AliTrack::GetMass(Float_t scale)
 {
 // Provide the particle mass.
+// By default the mass is returned in the units as it was stored in the track
+// structure. However, the user can select a different mass unit scale by
+// specification of the scale parameter.
+// The convention is that scale=1 corresponds to GeV/c**2, so specification
+// of scale=0.001 will provide the mass in MeV/c**2.
 // The error can be obtained by invoking GetResultError() after
 // invokation of GetMass().
+
  Double_t inv=GetInvariant();
  Double_t dinv=GetResultError();
  Double_t dm=0;
@@ -566,6 +602,11 @@ Double_t AliTrack::GetMass()
  {
  Double_t m=sqrt(inv);
  if (m) dm=dinv/(2.*m);
+ if (scale>0)
+ {
+  m*=fEscale/scale;
+  dm*=fEscale/scale;
+ }
  fDresult=dm;
  return m;
  }
@@ -584,19 +625,29 @@ Float_t AliTrack::GetCharge() const
  return fQ;
 }
 ///////////////////////////////////////////////////////////////////////////
-Double_t AliTrack::GetEnergy()
+Double_t AliTrack::GetEnergy(Float_t scale)
 {
 // Provide the particle's energy.
+// By default the energy is returned in the units as it was stored in the track
+// structure. However, the user can select a different energy unit scale by
+// specification of the scale parameter.
+// The convention is that scale=1 corresponds to GeV, so specification
+// of scale=0.001 will provide the energy in MeV.
 // The error can be obtained by invoking GetResultError() after
 // invokation of GetEnergy().
- Double_t E=GetScalar();
- if (E>0)
+ Double_t eE=GetScalar();
+ if (eE>0)
  {
-  return E;
+  if (scale>0)
+  {
+   eE*=fEscale/scale;
+   fDresult*=fEscale/scale;
+  }
+  return eE;
  }
  else
  {
-  cout << "*AliTrack::GetEnergy* Unphysical situation E = " << E << endl;
+  cout << "*AliTrack::GetEnergy* Unphysical situation E = " << eE << endl;
   cout << " Value 0 will be returned." << endl;
   return 0;
  }
@@ -610,14 +661,14 @@ void AliTrack::Decay(Double_t m1,Double_t m2,Double_t thcms,Double_t phicms)
 // thcms  : cms theta decay angle (in rad.) of m1
 // phicms : cms phi decay angle (in rad.) of m1
  
- Double_t M=GetMass();
+ Double_t mM=GetMass();
  
 // Compute the 4-momenta of the decay products in the cms
 // Note : p2=p1=pnorm for a 2-body decay
  Double_t e1=0;
- if (M) e1=((M*M)+(m1*m1)-(m2*m2))/(2.*M);
+ if (mM) e1=((mM*mM)+(m1*m1)-(m2*m2))/(2.*mM);
  Double_t e2=0;
- if (M) e2=((M*M)+(m2*m2)-(m1*m1))/(2.*M);
+ if (mM) e2=((mM*mM)+(m2*m2)-(m1*m1))/(2.*mM);
  Double_t pnorm=(e1*e1)-(m1*m1);
  if (pnorm>0.)
  {
@@ -645,10 +696,10 @@ void AliTrack::Decay(Double_t m1,Double_t m2,Double_t thcms,Double_t phicms)
  pprim2.SetInvariant(m2*m2);
 
  // Determine boost parameters from the parent particle
- Double_t E=GetEnergy();
+ Double_t eE=GetEnergy();
  p=Get3Vector();
  Ali4Vector pmu;
- pmu.SetVector(E,p);
+ pmu.SetVector(eE,p);
 
  AliBoost q;
  q.Set4Momentum(pmu);
@@ -715,9 +766,19 @@ void AliTrack::RemoveDecays()
  }
 }
 ///////////////////////////////////////////////////////////////////////////
-void AliTrack::AddSignal(AliSignal& s)
+void AliTrack::AddSignal(AliSignal& s,Int_t mode)
 {
 // Relate an AliSignal object to this track.
+//
+// mode = 0 : Only the reference to the specified signal is stored in
+//            the current track, without storing the (backward) reference
+//            to this track into the AliSignal structure. 
+//        1 : The (backward) reference to the current track is also automatically
+//            stored into the AliSignal (or derived) object specified in the
+//            input argument.
+//
+// The default is mode=0.
+
  if (!fSignals) fSignals=new TObjArray(1);
 
  // Check if this signal is already stored for this track
@@ -728,27 +789,53 @@ void AliTrack::AddSignal(AliSignal& s)
  }
 
  fSignals->Add(&s);
+ if (mode==1) s.AddTrack(*this,0);
 }
 ///////////////////////////////////////////////////////////////////////////
-void AliTrack::RemoveSignal(AliSignal& s)
+void AliTrack::RemoveSignal(AliSignal& s,Int_t mode)
 {
 // Remove related AliSignal object from this track.
+//
+// mode = 0 : Only the reference to the specified signal is removed from
+//            the current track, without removing the (backward) reference(s)
+//            to this track from the AliSignal structure. 
+//        1 : The (backward) reference(s) to the current track are also automatically
+//            removed from the AliSignal (or derived) object specified in the
+//            input argument.
+//
+// The default is mode=1.
+
  if (fSignals)
  {
   AliSignal* test=(AliSignal*)fSignals->Remove(&s);
   if (test) fSignals->Compress();
  }
+ if (mode==1) s.RemoveTrack(*this,0);
 }
 ///////////////////////////////////////////////////////////////////////////
-void AliTrack::RemoveSignals()
+void AliTrack::RemoveSignals(Int_t mode)
 {
 // Remove all related AliSignal objects from this track.
- if (fSignals)
+//
+// mode = 0 : All signal references are removed from the current track,
+//            without removing the (backward) references to this track from
+//            the corresponding AliSignal objects.
+//        1 : The (backward) references to the current track are also automatically
+//            removed from the corresponding AliSignal (or derived) objects.
+//
+// The default is mode=1.
+
+ if (!fSignals) return;
+
+ Int_t ns=GetNsignals();
+ for (Int_t i=0; i<ns; i++)
  {
-  fSignals->Clear();
-  delete fSignals;
-  fSignals=0;
+  AliSignal* sx=(AliSignal*)fSignals->At(i);
+  if (sx && mode==1) sx->RemoveTrack(*this,0);
  }
+
+ delete fSignals;
+ fSignals=0;
 }
 ///////////////////////////////////////////////////////////////////////////
 Int_t AliTrack::GetNsignals() const
@@ -759,6 +846,21 @@ Int_t AliTrack::GetNsignals() const
  return nsig;
 }
 ///////////////////////////////////////////////////////////////////////////
+Int_t AliTrack::GetNsignals(const char* classname) const
+{
+// Provide the number of stored signals of the specified class.
+
+ Int_t nsigs=0;
+ for (Int_t isig=1; isig<=GetNsignals(); isig++)
+ {
+  TObject* obj=GetSignal(isig);
+  if (!obj) continue;
+
+  if (obj->InheritsFrom(classname)) nsigs++;
+ }
+ return nsigs;
+} 
+///////////////////////////////////////////////////////////////////////////
 AliSignal* AliTrack::GetSignal(Int_t j) const
 {
 // Provide the related AliSignal number j.
@@ -895,7 +997,7 @@ void AliTrack::SetBeginPoint(AliPosition& p)
  fBegin=new AliPositionObj(p);
 }
 ///////////////////////////////////////////////////////////////////////////
-AliPosition* AliTrack::GetBeginPoint()
+AliPosition* AliTrack::GetBeginPoint() const
 {
 // Provide the position of the track begin-point.
  return fBegin;
@@ -908,7 +1010,7 @@ void AliTrack::SetEndPoint(AliPosition& p)
  fEnd=new AliPositionObj(p);
 }
 ///////////////////////////////////////////////////////////////////////////
-AliPosition* AliTrack::GetEndPoint()
+AliPosition* AliTrack::GetEndPoint() const
 {
 // Provide the position of the track end-point.
  return fEnd;
@@ -925,7 +1027,7 @@ void AliTrack::SetReferencePoint(AliPosition& p)
  fRef=new AliPositionObj(p);
 }
 ///////////////////////////////////////////////////////////////////////////
-AliPosition* AliTrack::GetReferencePoint()
+AliPosition* AliTrack::GetReferencePoint() const
 {
 // Provide the position of the track reference-point.
 // The reference-point is the point on the track in which the 
@@ -955,25 +1057,41 @@ void AliTrack::SetMass()
  }
 }
 ///////////////////////////////////////////////////////////////////////////
-Double_t AliTrack::GetPt()
+Double_t AliTrack::GetPt(Float_t scale)
 {
-// Provide trans. momentum value w.r.t. z-axis.
+// Provide the transverse momentum value w.r.t. z-axis.
+// By default the value is returned in the units as it was stored in the track
+// structure. However, the user can select a different momentum unit scale by
+// specification of the scale parameter.
+// The convention is that scale=1 corresponds to GeV/c, so specification
+// of scale=0.001 will provide the transverse momentum in MeV/c.
 // The error on the value can be obtained by GetResultError()
 // after invokation of GetPt().
  Ali3Vector v;
  v=GetVecTrans();
  Double_t norm=v.GetNorm();
  fDresult=v.GetResultError();
+ if (scale>0)
+ {
+  norm*=fEscale/scale;
+  fDresult*=fEscale/scale;
+ }
 
  return norm;
 }
 ///////////////////////////////////////////////////////////////////////////
-Double_t AliTrack::GetPl()
+Double_t AliTrack::GetPl(Float_t scale)
 {
-// Provide long. momentum value w.r.t. z-axis.
+// Provide the longitudinal momentum value w.r.t. z-axis.
+// By default the value is returned in the units as it was stored in the track
+// structure. However, the user can select a different momentum unit scale by
+// specification of the scale parameter.
+// The convention is that scale=1 corresponds to GeV/c, so specification
+// of scale=0.001 will provide the longitudinal momentum in MeV/c.
 // Note : the returned value can also be negative.
 // The error on the value can be obtained by GetResultError()
 // after invokation of GetPl().
+
  Ali3Vector v;
  v=GetVecLong();
 
@@ -983,34 +1101,66 @@ Double_t AliTrack::GetPl()
  Double_t a[3];
  v.GetVector(a,"sph");
  if (cos(a[1])<0) pl=-pl;
+ if (scale>0)
+ {
+  pl*=fEscale/scale;
+  fDresult*=fEscale/scale;
+ }
 
  return pl;
 }
 ///////////////////////////////////////////////////////////////////////////
-Double_t AliTrack::GetEt()
+Double_t AliTrack::GetEt(Float_t scale)
 {
-// Provide trans. energy value w.r.t. z-axis.
+// Provide transverse energy value w.r.t. z-axis.
+// By default the value is returned in the units as it was stored in the track
+// structure. However, the user can select a different energy unit scale by
+// specification of the scale parameter.
+// The convention is that scale=1 corresponds to GeV, so specification
+// of scale=0.001 will provide the transverse energy in MeV.
 // The error on the value can be obtained by GetResultError()
 // after invokation of GetEt().
+
  Double_t et=GetScaTrans();
+ if (scale>0)
+ {
+  et*=fEscale/scale;
+  fDresult*=fEscale/scale;
+ }
 
  return et;
 }
 ///////////////////////////////////////////////////////////////////////////
-Double_t AliTrack::GetEl()
+Double_t AliTrack::GetEl(Float_t scale)
 {
-// Provide long. energy value w.r.t. z-axis.
+// Provide longitudinal energy value w.r.t. z-axis.
+// By default the value is returned in the units as it was stored in the track
+// structure. However, the user can select a different energy unit scale by
+// specification of the scale parameter.
+// The convention is that scale=1 corresponds to GeV, so specification
+// of scale=0.001 will provide the longitudinal energy in MeV.
 // Note : the returned value can also be negative.
 // The error on the value can be obtained by GetResultError()
 // after invokation of GetEl().
+
  Double_t el=GetScaLong();
+ if (scale>0)
+ {
+  el*=fEscale/scale;
+  fDresult*=fEscale/scale;
+ }
 
  return el;
 }
 ///////////////////////////////////////////////////////////////////////////
-Double_t AliTrack::GetMt()
+Double_t AliTrack::GetMt(Float_t scale)
 {
 // Provide transverse mass value w.r.t. z-axis.
+// By default the value is returned in the units as it was stored in the track
+// structure. However, the user can select a different energy unit scale by
+// specification of the scale parameter.
+// The convention is that scale=1 corresponds to GeV, so specification
+// of scale=0.001 will provide the transverse mass in MeV.
 // The error on the value can be obtained by GetResultError()
 // after invokation of GetMt().
  Double_t pt=GetPt();
@@ -1023,6 +1173,11 @@ Double_t AliTrack::GetMt()
  if (mt) dmt2=(pow((pt*dpt),2)+pow((m*dm),2))/(mt*mt);
 
  fDresult=sqrt(dmt2);
+ if (scale>0)
+ {
+  mt*=fEscale/scale;
+  fDresult*=fEscale/scale;
+ }
  return mt;
 }
 ///////////////////////////////////////////////////////////////////////////
@@ -1084,7 +1239,7 @@ void AliTrack::SetImpactPoint(AliPosition& p,TString q)
  }
 }
 ///////////////////////////////////////////////////////////////////////////
-AliPosition* AliTrack::GetImpactPoint(TString q)
+AliPosition* AliTrack::GetImpactPoint(TString q) const
 {
 // Provide the position of the impact-point in the plane "q=0".
 // Here q denotes one of the axes X, Y or Z.
@@ -1132,48 +1287,40 @@ void AliTrack::SetClosestPoint(AliPosition& p)
  fClosest=new AliPositionObj(p);
 }
 ///////////////////////////////////////////////////////////////////////////
-AliPosition* AliTrack::GetClosestPoint()
+AliPosition* AliTrack::GetClosestPoint() const
 {
 // Provide the point of closest approach w.r.t. some reference
  return fClosest;
 }
 ///////////////////////////////////////////////////////////////////////////
-void AliTrack::SetChi2(Float_t chi2)
+void AliTrack::SetEscale(Float_t scale)
 {
-// Set the chi-squared value of the track fit.
- if (chi2<0)
- {
-  cout << " *AliTrack::SetChi2* Invalid chi2 value : " << chi2 << endl;
- }
- else
- {
-  fChi2=chi2;
- }
-}
-///////////////////////////////////////////////////////////////////////////
-void AliTrack::SetNdf(Int_t ndf)
-{
-// Set the number of degrees of freedom for the track fit.
- if (ndf<0)
+// Indicate the energy/momentum scale as used by the user.
+// The convention is that scale=1 indicates values in units
+// of GeV, GeV/c or GeV/c**2.
+// So, in case one decides to store values in units of MeV, MeV/c or MeV/c**2
+// the scale indicator should be set to scale=0.001.
+//
+// By default scale=1 is set in the constructor.
+
+ if (scale>0)
  {
-  cout << " *AliTrack::SetNdf* Invalid ndf value : " << ndf << endl;
+  fEscale=scale;
  }
  else
  {
-  fNdf=ndf;
+  cout << " *AliTrack::SetEscale* Invalid scale value : " << scale << endl;
  }
 }
 ///////////////////////////////////////////////////////////////////////////
-Float_t AliTrack::GetChi2() const
-{
-// Provide the chi-squared value of the track fit.
- return fChi2;
-}
-///////////////////////////////////////////////////////////////////////////
-Int_t AliTrack::GetNdf() const
+Float_t AliTrack::GetEscale() const
 {
-// Provide the number of degrees of freedom for the track fit.
- return fNdf;
+// Provide the energy/momentum scale as used by the user.
+// The convention is that scale=1 indicates values in units
+// of GeV, GeV/c or GeV/c**2.
+// So, a value of scale=0.001 indicates that energy/momentum values are
+// stored in units of MeV, MeV/c or MeV/c**2.
+ return fEscale;
 }
 ///////////////////////////////////////////////////////////////////////////
 void AliTrack::SetParticleCode(Int_t code)
@@ -1188,13 +1335,13 @@ Int_t AliTrack::GetParticleCode() const
  return fCode;
 }
 ///////////////////////////////////////////////////////////////////////////
-void AliTrack::SetParentTrack(AliTrack* t)
+void AliTrack::SetParentTrack(AliTrack * const t)
 {
 // Set pointer to the parent track.
  fParent=t;
 }
 ///////////////////////////////////////////////////////////////////////////
-AliTrack* AliTrack::GetParentTrack()
+AliTrack* AliTrack::GetParentTrack() const
 {
 // Provide pointer to the parent track.
  return fParent;
@@ -1212,7 +1359,7 @@ Float_t AliTrack::GetProb() const
  return fProb;
 }
 ///////////////////////////////////////////////////////////////////////////
-void AliTrack::SetFitDetails(TObject* obj)
+void AliTrack::SetFitDetails(const TObject* obj)
 {
 // Enter the object containing the fit details.
 // In case an object to hold fit details was already present, this
@@ -1248,7 +1395,7 @@ void AliTrack::SetFitDetails(TObject* obj)
  if (obj) fFit=obj->Clone();
 }
 ///////////////////////////////////////////////////////////////////////////
-TObject* AliTrack::GetFitDetails()
+TObject* AliTrack::GetFitDetails() const
 {
 // Provide the pointer to the object containing the fit details.
  return fFit;
@@ -1261,7 +1408,7 @@ void AliTrack::SetTimestamp(AliTimestamp& t)
  fTstamp=new AliTimestamp(t);
 }
 ///////////////////////////////////////////////////////////////////////////
-AliTimestamp* AliTrack::GetTimestamp()
+AliTimestamp* AliTrack::GetTimestamp() const
 {
 // Provide the timestamp of this track.
  return fTstamp;
@@ -1277,6 +1424,154 @@ void AliTrack::RemoveTimestamp()
  }
 }
 ///////////////////////////////////////////////////////////////////////////
+Double_t AliTrack::GetDistance(AliPosition* const p,Float_t scale)
+{
+// Provide distance of the current track to the position p.
+// The error on the result can be obtained as usual by invoking
+// GetResultError() afterwards. 
+//
+// By default the distance will be provided in the metric unit scale of
+// the AliPosition p.
+// However, the user can select a different metric unit scale by
+// specification of the scale parameter.
+// The convention is that scale=1 corresponds to meter, so specification
+// of scale=0.01 will provide the distance in cm.
+// As such it is possible to obtain a correctly computed distance even in case
+// the track parameters have a different unit scale.
+// However, it is recommended to work always with one single unit scale.
+//
+// Note : In case of incomplete information, a distance value of -1 is
+//        returned.
+ 
+ Double_t dist=-1.;
+ fDresult=0.;
+
+ if (!p) return dist;
+
+ // Obtain a defined position on this track
+ AliPosition* rx=fRef;
+ if (!rx) rx=fBegin;
+ if (!rx) rx=fEnd;
+
+ if (!rx) return dist;
+
+ Ali3Vector p1=Get3Momentum();
+
+ if (p1.GetNorm() <= 0.) return dist;
+
+ Ali3Vector r0=(Ali3Vector)(*rx);
+
+ Float_t tscale=rx->GetUnitScale();
+ Float_t pscale=p->GetUnitScale();
+ if ((tscale/pscale > 1.1) || (pscale/tscale > 1.1)) r0=r0*(tscale/pscale);
+ 
+ // Obtain the direction unit vector of this track
+ Double_t vec[3];
+ Double_t err[3];
+ p1.GetVector(vec,"sph");
+ p1.GetErrors(err,"sph");
+ vec[0]=1.;
+ err[0]=0.;
+ p1.SetVector(vec,"sph");
+ p1.SetErrors(err,"sph");
+
+ Ali3Vector q=(Ali3Vector)(*p);
+ Ali3Vector r=q-r0;
+ Ali3Vector d=r.Cross(p1);
+ dist=d.GetNorm();
+ fDresult=d.GetResultError();
+ if (scale>0)
+ {
+  dist*=pscale/scale;
+  fDresult*=pscale/scale;
+ }
+ return dist;
+}
+///////////////////////////////////////////////////////////////////////////
+Double_t AliTrack::GetDistance(AliTrack* const t,Float_t scale)
+{
+// Provide distance of the current track to the track t.
+// The error on the result can be obtained as usual by invoking
+// GetResultError() afterwards. 
+//
+// By default the distance will be provided in the metric unit scale of
+// the current track.
+// This implies that the results of t1.GetDistance(t2) and t2.GetDistance(t1)
+// may be numerically different in case t1 and t2 have different metric units.
+// However, the user can specify a required metric unit scale by specification
+// of the scale parameter.
+// The convention is that scale=1 corresponds to meter, so specification
+// of scale=0.01 will provide the distance in cm.
+// As such it is possible to obtain a correctly computed distance even in case
+// the track parameters have a different unit scale.
+// However, it is recommended to work always with one single unit scale.
+//
+// Note : In case of incomplete information, a distance value of -1 is
+//        returned.
+ 
+ Double_t dist=-1.;
+ fDresult=0.;
+
+ if (!t) return dist;
+
+ // Obtain a defined position on this track
+ AliPosition* rx=fRef;
+ if (!rx) rx=fBegin;
+ if (!rx) rx=fEnd;
+
+ if (!rx) return dist;
+
+ // Obtain a defined position on track t
+ AliPosition* ry=t->GetReferencePoint();
+ if (!ry) ry=t->GetBeginPoint();
+ if (!ry) ry=t->GetEndPoint();
+
+ if (!ry) return dist;
+ 
+ Ali3Vector p1=Get3Momentum();
+ Ali3Vector p2=t->Get3Momentum();
+
+ if (p1.GetNorm() <= 0. || p2.GetNorm() <= 0.) return dist;
+
+ // The vector normal to both track directions
+ Ali3Vector n=p1.Cross(p2);
+
+ Float_t scalex=rx->GetUnitScale();
+ Float_t scaley=ry->GetUnitScale();
+
+ if (n.GetNorm() > 1.e-10)
+ {
+  // Normalise n to a unit vector
+  Double_t vec[3];
+  Double_t err[3];
+  n.GetVector(vec,"sph");
+  n.GetErrors(err,"sph");
+  vec[0]=1.;
+  err[0]=0.;
+  n.SetVector(vec,"sph");
+  n.SetErrors(err,"sph");
+  Ali3Vector r1=(Ali3Vector)(*rx);
+  Ali3Vector r2=(Ali3Vector)(*ry);
+  // Correct components of r2 in case of different unit scales
+  if ((scaley/scalex > 1.1) || (scalex/scaley > 1.1)) r2=r2*(scaley/scalex);
+  Ali3Vector r=r1-r2;
+  dist=fabs(r.Dot(n));
+  fDresult=r.GetResultError();
+ }
+ else // Parallel tracks
+ {
+  dist=t->GetDistance(rx);
+  fDresult=t->GetResultError();
+ }
+
+ if (scale>0)
+ {
+  dist*=scalex/scale;
+  fDresult*=scalex/scale;
+ }
+ return dist;
+}
+///////////////////////////////////////////////////////////////////////////
 TObject* AliTrack::Clone(const char* name) const
 {
 // Make a deep copy of the current object and provide the pointer to the copy.