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[u/mrichter/AliRoot.git] / TPC / AliHelix.h
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7f572c00 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
18class AliCluster;
19class AliKalmanTrack;
20
21class AliHelix : public TObject {
22public:
23 AliHelix();
24 AliHelix(const AliHelix &t);
25 AliHelix(const AliKalmanTrack &t);
26 AliHelix(Double_t x[3], Double_t p[3], Double_t charge=1, Double_t conversion=0.);
27 virtual ~AliHelix(){};
28 inline void Evaluate(Double_t t, Double_t r[3]);
29 void Evaluate(Double_t t, Double_t r[3], //radius vector
30 Double_t g[3], //first defivatives
31 Double_t gg[3]); //second derivatives
32 void GetMomentum(Double_t phase, Double_t p[4], Double_t conversion=0.); // return momentum
33 void GetAngle(Double_t t1, AliHelix &h, Double_t t2, Double_t angle[3]);
34 inline Double_t GetHelixR(Double_t phase=0);
35 inline Double_t GetHelixZ(Double_t phase=0);
36
37 Double_t GetPhase(Double_t x0, Double_t y0); //return phase for nearest point
38 Double_t GetPhaseZ(Double_t z0); // return phase for given z
39 Int_t GetPhase(Double_t r0, Double_t t[2]); //return phase for the nearest point
40 Int_t GetRPHIintersections(AliHelix &h, Double_t phase[2][2], Double_t ri[2], Double_t cut=3.);
41 Int_t LinearDCA(AliHelix &h, Double_t &t1, Double_t &t2,
42 Double_t &R, Double_t &dist);
43 //
44 Int_t ParabolicDCA(AliHelix&h, //helixes
45 Double_t &t1, Double_t &t2,
46 Double_t &R, Double_t &dist, Int_t iter=1);
47
48 Double_t fHelix[9]; //helix parameters
49 private:
50 ClassDef(AliHelix,1) // AliHelix
51};
52
53void AliHelix::Evaluate(Double_t t, Double_t r[3]){
54 //
55 // calculate poitition at given phase t
56 Double_t phase=fHelix[4]*t+fHelix[2];
57 r[0] = fHelix[5] + TMath::Sin(phase)/fHelix[4];
58 r[1] = fHelix[0] - TMath::Cos(phase)/fHelix[4];
59 r[2] = fHelix[1] + fHelix[3]*t;
60}
61
62inline Double_t AliHelix::GetHelixR(Double_t phase)
63{
64 Double_t x[3];
65 Evaluate(phase,x);
66 return TMath::Sqrt(x[0]*x[0]+x[1]*x[1]);
67}
68
69inline Double_t AliHelix::GetHelixZ(Double_t phase)
70{
71 Double_t x[3];
72 Evaluate(phase,x);
73 return x[2];
74}
75
76
77#endif
78
79