HLT/ITS/AliL3ITStrack.cxx

   1 /**************************************************************************
   2  * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
   3  *                                                                        *
   4  * Author: The ALICE Off-line Project.                                    *
   5  * Contributors are mentioned in the code where appropriate.              *
   6  *                                                                        *
   7  * Permission to use, copy, modify and distribute this software and its   *
   8  * documentation strictly for non-commercial purposes is hereby granted   *
   9  * without fee, provided that the above copyright notice appears in all   *
  10  * copies and that both the copyright notice and this permission notice   *
  11  * appear in the supporting documentation. The authors make no claims     *
  12  * about the suitability of this software for any purpose. It is          *
  13  * provided "as is" without express or implied warranty.                  *
  14  **************************************************************************/
  15
  16 //-------------------------------------------------------------------------
  17 //                Implementation of the HLT ITS track class
  18 //
  19 //          Origin: Cvetan Cheshkov, CERN, Cvetan.Cheshkov@cern.ch
  20 //-------------------------------------------------------------------------
  21
  22 #include <TMath.h>
  23
  24 #include "AliL3ITStrack.h"
  25
  26 ClassImp(AliL3ITStrack)
  27
  28 //____________________________________________________________________________
  29 AliL3ITStrack::AliL3ITStrack()
  30               :AliITStrackV2()
  31 {
  32   //------------------------------------------------------------------
  33   //Constructor
  34   //------------------------------------------------------------------
  35 }
  36
  37 //____________________________________________________________________________
  38 AliL3ITStrack::AliL3ITStrack(AliESDtrack& t)
  39               :AliITStrackV2(t)
  40 {
  41   //------------------------------------------------------------------
  42   //Constructor
  43   //------------------------------------------------------------------
  44 }
  45
  46 //____________________________________________________________________________
  47 AliL3ITStrack::AliL3ITStrack(const AliL3ITStrack& t)
  48               : AliITStrackV2(t)
  49 {
  50   //------------------------------------------------------------------
  51   //Copy constructor
  52   //------------------------------------------------------------------
  53 }
  54
  55 //_____________________________________________________________________________
  56 Int_t AliL3ITStrack::Compare(const TObject *o) const {
  57   //-----------------------------------------------------------------
  58   // This function compares tracks according to the their curvature
  59   //-----------------------------------------------------------------
  60   AliL3ITStrack *t=(AliL3ITStrack*)o;
  61   Double_t co=TMath::Abs(t->Get1Pt());
  62   Double_t c =TMath::Abs(Get1Pt());
  63   //  Double_t co=t->GetSigmaY2()*t->GetSigmaZ2();
  64   //  Double_t c =GetSigmaY2()*GetSigmaZ2();
  65   if (c>co) return 1;
  66   else if (c<co) return -1;
  67   return 0;
  68 }
  69
  70 Bool_t AliL3ITStrack::GetPxPyPzAt(Double_t x,Double_t *p) const {
  71   //---------------------------------------------------------------------
  72   // This function returns the global track momentum components
  73   // at the position "x" using the helix track approximation
  74   //---------------------------------------------------------------------
  75   p[0]=fP4;
  76   p[1]=fP2+(x-fX)*fP4/AliKalmanTrack::GetConvConst();
  77   p[2]=fP3;
  78
  79   if (TMath::Abs(p[0])<=0)        return kFALSE;
  80   if (TMath::Abs(p[1])> 0.999999) return kFALSE;
  81
  82   Double_t pt=1./TMath::Abs(p[0]);
  83   Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
  84   Double_t r=TMath::Sqrt(1 - p[1]*p[1]);
  85   p[0]=pt*(r*cs - p[1]*sn); p[1]=pt*(p[1]*cs + r*sn); p[2]=pt*p[2];
  86
  87   return kTRUE;
  88 }