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1 | #ifndef ALIHELIX_H |
| 2 | #define ALIHELIX_H |
| 3 | |
| 4 | /* Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. * |
| 5 | * See cxx source for full Copyright notice */ |
| 6 | |
| 7 | |
| 8 | //------------------------------------------------------------------------- |
| 9 | // Class AliHelix |
| 10 | // |
| 11 | // Origin: Marian Ivanov marian.ivanov@cern.ch |
| 12 | //------------------------------------------------------------------------- |
| 13 | |
| 14 | #include <TObject.h> |
| 15 | #include <TMath.h> |
| 16 | |
| 17 | |
| 18 | class AliCluster; |
| 19 | class AliKalmanTrack; |
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20 | class AliExternalTrackParam; |
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21 | |
| 22 | class AliHelix : public TObject { |
| 23 | public: |
| 24 | AliHelix(); |
| 25 | AliHelix(const AliHelix &t); |
| 26 | AliHelix(const AliKalmanTrack &t); |
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27 | AliHelix(const AliExternalTrackParam &t); |
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28 | AliHelix(Double_t x[3], Double_t p[3], Double_t charge=1, Double_t conversion=0.); |
| 29 | virtual ~AliHelix(){}; |
| 30 | inline void Evaluate(Double_t t, Double_t r[3]); |
| 31 | void Evaluate(Double_t t, Double_t r[3], //radius vector |
| 32 | Double_t g[3], //first defivatives |
| 33 | Double_t gg[3]); //second derivatives |
| 34 | void GetMomentum(Double_t phase, Double_t p[4], Double_t conversion=0.); // return momentum |
| 35 | void GetAngle(Double_t t1, AliHelix &h, Double_t t2, Double_t angle[3]); |
| 36 | inline Double_t GetHelixR(Double_t phase=0); |
| 37 | inline Double_t GetHelixZ(Double_t phase=0); |
| 38 | |
| 39 | Double_t GetPhase(Double_t x0, Double_t y0); //return phase for nearest point |
| 40 | Double_t GetPhaseZ(Double_t z0); // return phase for given z |
| 41 | Int_t GetPhase(Double_t r0, Double_t t[2]); //return phase for the nearest point |
| 42 | Int_t GetRPHIintersections(AliHelix &h, Double_t phase[2][2], Double_t ri[2], Double_t cut=3.); |
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43 | Int_t GetClosestPhases(AliHelix &h, Double_t phase[2][2]); |
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44 | Int_t LinearDCA(AliHelix &h, Double_t &t1, Double_t &t2, |
| 45 | Double_t &R, Double_t &dist); |
| 46 | // |
| 47 | Int_t ParabolicDCA(AliHelix&h, //helixes |
| 48 | Double_t &t1, Double_t &t2, |
| 49 | Double_t &R, Double_t &dist, Int_t iter=1); |
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50 | Int_t ParabolicDCA2(AliHelix&h, //helixes |
| 51 | Double_t &t1, Double_t &t2, |
| 52 | Double_t &R, Double_t &dist, Double_t err[3], Int_t iter=1); |
| 53 | Double_t GetHelix(Int_t i) const{return fHelix[i];} |
| 54 | public: |
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55 | Double_t fHelix[9]; //helix parameters |
| 56 | private: |
| 57 | ClassDef(AliHelix,1) // AliHelix |
| 58 | }; |
| 59 | |
| 60 | void AliHelix::Evaluate(Double_t t, Double_t r[3]){ |
| 61 | // |
| 62 | // calculate poitition at given phase t |
| 63 | Double_t phase=fHelix[4]*t+fHelix[2]; |
| 64 | r[0] = fHelix[5] + TMath::Sin(phase)/fHelix[4]; |
| 65 | r[1] = fHelix[0] - TMath::Cos(phase)/fHelix[4]; |
| 66 | r[2] = fHelix[1] + fHelix[3]*t; |
| 67 | } |
| 68 | |
| 69 | inline Double_t AliHelix::GetHelixR(Double_t phase) |
| 70 | { |
| 71 | Double_t x[3]; |
| 72 | Evaluate(phase,x); |
| 73 | return TMath::Sqrt(x[0]*x[0]+x[1]*x[1]); |
| 74 | } |
| 75 | |
| 76 | inline Double_t AliHelix::GetHelixZ(Double_t phase) |
| 77 | { |
| 78 | Double_t x[3]; |
| 79 | Evaluate(phase,x); |
| 80 | return x[2]; |
| 81 | } |
| 82 | |
| 83 | |
| 84 | #endif |
| 85 | |
| 86 | |
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