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LorentzVector.hh
1 //----------------------------------------------------------------------
2 // This file distributed with FastJet has been obtained from SpartyJet
3 // v2.20.0 by Pierre-Antoine Delsart, Kurtis L. Geerlings, Joey
4 // Huston, Brian T. Martin and Chris Vermilion
5 // For details, see http://www.pa.msu.edu/~huston/SpartyJet/
6 // http://projects.hepforge.org/spartyjet/
7 //
8 // Changes from the original file are listed below.
9 //----------------------------------------------------------------------
10 
11 // History of changes compared to the original LorentzVector.hh file
12 //
13 // 2011-11-14 Gregory Soyez <soyez@fastjet.fr>
14 //
15 // * removed some harmless warnings coming with the -Wshadow gcc option
16 //
17 // 2009-01-15 Gregory Soyez <soyez@fastjet.fr>
18 //
19 // * put the code in the fastjet::atlas namespace
20 
21 #ifndef _LORENTZ_VECTOR_HH_
22 #define _LORENTZ_VECTOR_HH_
23 
24 #include <cmath>
25 #include <fastjet/internal/base.hh>
26 
27 #ifndef M_PI
28 #define M_PI 3.141592653589793238462643383279502884197
29 #endif
30 
31 FASTJET_BEGIN_NAMESPACE
32 
33 namespace atlas{
34 
35 class LorentzVector
36 {
37  public:
38 
39  double px,py,pz,E;
40 
41  LorentzVector(): px(0), py(0), pz(0), E(0) {}
42  LorentzVector(double p1, double p2, double p3, double p0): px(p1), py(p2), pz(p3), E(p0) {}
43  LorentzVector(const LorentzVector& lv): px(lv.px), py(lv.py), pz(lv.pz), E(lv.E) {}
44  double p() const {return sqrt(px*px + py*py + pz*pz);}
45  double pt() const {return sqrt(px*px + py*py);}
46  double mt() const {return sqrt((E-pz)*(E+pz));}
47  double y() const {return 0.5*log((E + pz)/(E - pz));}
48  double Et() const {return E/p()*pt();}
49  inline double et() const {return Et();}
50  inline double e() const {return E;}
51  double eta() const {return 0.5*log((p() + pz)/(p() - pz));}
52  double phi() const
53  {
54  double r = atan2(py,px);
55  if(r < 0)
56  r += 2*M_PI;
57  return r;
58  }
59  void add(LorentzVector v)
60  {
61  px += v.px;
62  py += v.py;
63  pz += v.pz;
64  E += v.E;
65  }
66  void subtract(LorentzVector v)
67  {
68  px -= v.px;
69  py -= v.py;
70  pz -= v.pz;
71  E -= v.E;
72  }
73  bool isEqual(LorentzVector v)
74  {
75  return px == v.px && py == v.py && pz == v.pz && E == v.E;
76  }
77 };
78 
79 } // namespace atlas
80 
81 FASTJET_END_NAMESPACE
82 
83 #endif