| Geant4 Cross Reference |
1 // -*- C++ -*-
2 // ---------------------------------------------------------------------------
3 //
4 // This file is a part of the CLHEP - a Class Library for High Energy Physics.
5 //
6 // This is the implementation of the HepBoostY class.
7 //
8
9 #include "CLHEP/Vector/BoostY.h"
10 #include "CLHEP/Vector/Boost.h"
11 #include "CLHEP/Vector/Rotation.h"
12 #include "CLHEP/Vector/LorentzRotation.h"
13
14 #include <cmath>
15 #include <iostream>
16
17 namespace CLHEP {
18
19 // ---------- Constructors and Assignment:
20
21 HepBoostY & HepBoostY::set (double bbeta) {
22 double b2 = bbeta*bbeta;
23 if (b2 >= 1) {
24 std::cerr << "HepBoostY::set() - "
25 << "Beta supplied to set HepBoostY represents speed >= c." << std::endl;
26 beta_ = 1.0 - 1.0E-8; // NaN-proofing
27 gamma_ = 1.0 / std::sqrt(1.0 - b2);
28 return *this;
29 }
30 beta_ = bbeta;
31 gamma_ = 1.0 / std::sqrt(1.0 - b2);
32 return *this;
33 }
34
35 // ---------- Accessors:
36
37 HepRep4x4 HepBoostY::rep4x4() const {
38 double bg = beta_*gamma_;
39 return HepRep4x4( 1, 0, 0, 0,
40 0, gamma_, 0, bg,
41 0, 0, 1, 0,
42 0, bg, 0, gamma_ );
43 }
44
45 HepRep4x4Symmetric HepBoostY::rep4x4Symmetric() const {
46 double bg = beta_*gamma_;
47 return HepRep4x4Symmetric ( 1, 0, 0, 0,
48 gamma_, 0, bg,
49 1, 0,
50 gamma_ );
51 }
52
53 // ---------- Decomposition:
54
55 void HepBoostY::decompose (HepRotation & rotation, HepBoost & boost) const {
56 HepAxisAngle vdelta = HepAxisAngle();
57 rotation = HepRotation(vdelta);
58 Hep3Vector bbeta = boostVector();
59 boost = HepBoost(bbeta);
60 }
61
62 void HepBoostY::decompose (HepAxisAngle & rotation, Hep3Vector & boost) const {
63 rotation = HepAxisAngle();
64 boost = boostVector();
65 }
66
67 void HepBoostY::decompose (HepBoost & boost, HepRotation & rotation) const {
68 HepAxisAngle vdelta = HepAxisAngle();
69 rotation = HepRotation(vdelta);
70 Hep3Vector bbeta = boostVector();
71 boost = HepBoost(bbeta);
72 }
73
74 void HepBoostY::decompose (Hep3Vector & boost, HepAxisAngle & rotation) const {
75 rotation = HepAxisAngle();
76 boost = boostVector();
77 }
78
79 // ---------- Comparisons:
80
81 double HepBoostY::distance2( const HepBoost & b ) const {
82 return b.distance2(*this);
83 }
84
85 double HepBoostY::distance2( const HepRotation & r ) const {
86 double db2 = norm2();
87 double dr2 = r.norm2();
88 return (db2 + dr2);
89 }
90
91 double HepBoostY::distance2( const HepLorentzRotation & lt ) const {
92 HepBoost b1;
93 HepRotation r1;
94 lt.decompose(b1,r1);
95 double db2 = distance2(b1);
96 double dr2 = r1.norm2();
97 return (db2 + dr2);
98 }
99
100 bool HepBoostY::isNear (const HepRotation & r, double epsilon) const {
101 double db2 = norm2();
102 if (db2 > epsilon*epsilon) return false;
103 double dr2 = r.norm2();
104 return (db2+dr2 <= epsilon*epsilon);
105 }
106
107 bool HepBoostY::isNear ( const HepLorentzRotation & lt,
108 double epsilon ) const {
109 HepBoost b1;
110 HepRotation r1;
111 double db2 = distance2(b1);
112 lt.decompose(b1,r1);
113 if (db2 > epsilon*epsilon) return false;
114 double dr2 = r1.norm2();
115 return (db2 + dr2);
116 }
117
118 // ---------- Properties:
119
120 void HepBoostY::rectify() {
121 // Assuming the representation of this is close to a true pure boost,
122 // but may have drifted due to round-off error from many operations,
123 // this forms an "exact" pure BoostY matrix for again.
124
125 double b2 = beta_*beta_;
126 if (b2 >= 1) {
127 beta_ = 1.0 - 1.0e-8; // Nan-proofing
128 b2 = beta_*beta_;
129 }
130 gamma_ = 1.0 / std::sqrt(1.0 - b2);
131 }
132
133 // ---------- Application:
134
135 // ---------- Operations in the group of 4-Rotations
136
137 HepBoostY HepBoostY::operator * (const HepBoostY & b) const {
138 return HepBoostY ( (beta()+b.beta()) / (1+beta()*b.beta()) );
139 }
140 HepLorentzRotation HepBoostY::operator * (const HepBoost & b) const {
141 HepLorentzRotation me (*this);
142 return me*b;
143 }
144 HepLorentzRotation HepBoostY::operator * (const HepRotation & r) const {
145 HepLorentzRotation me (*this);
146 return me*r;
147 }
148 HepLorentzRotation HepBoostY::operator * (const HepLorentzRotation & lt) const {
149 HepLorentzRotation me (*this);
150 return me*lt;
151 }
152
153 // ---------- I/O
154
155 std::ostream & HepBoostY::print( std::ostream & os ) const {
156 os << "Boost in Y direction (beta = " << beta_
157 << ", gamma = " << gamma_ << ") ";
158 return os;
159 }
160
161 } // namespace CLHEP
162