| Geant4 Cross Reference |
1 // -*- C++ -*- 1
2 // -------------------------------------------
3 //
4 // This file is a part of the CLHEP - a Class
5 //
6 // SpaceVector
7 //
8 // This is the implementation of the subset of
9 // class which originated from the ZOOM SpaceV
10 // intrinsic properties or propeties relative
11 //
12
13 #include "CLHEP/Vector/ThreeVector.h"
14
15 #include <cmath>
16
17 namespace CLHEP {
18
19 //-********************************
20 // - 5 -
21 // Intrinsic properties of a vector
22 // and properties relative to a direction
23 //
24 //-********************************
25
26 double Hep3Vector::beta() const {
27 double b = std::sqrt(mag2());
28 // if (b >= 1) {
29 // std::cerr << "Hep3Vector::beta() - "
30 // << "Beta taken for Hep3Vector of at le
31 // }
32 return b;
33 }
34
35 double Hep3Vector::gamma() const {
36 double bbeta = std::sqrt(mag2());
37 // if (bbeta == 1) {
38 // std::cerr << "Hep3Vector::gamma() - "
39 // << "Gamma taken for Hep3Vector of unit
40 // << std::endl;
41 // }
42 // if (bbeta > 1) {
43 // std::cerr << "Hep3Vector::gamma() - "
44 // << "Gamma taken for Hep3Vector of more
45 // << "the sqrt function would return NAN
46 // }
47 return 1/std::sqrt(1-bbeta*bbeta);
48 }
49
50 double Hep3Vector::rapidity() const {
51 // if (std::fabs(z()) == 1) {
52 // std::cerr << "Hep3Vector::rapidity() - "
53 // << "Rapidity in Z direction taken for
54 // << "the log should return infinity" <,
55 // }
56 // if (std::fabs(z()) > 1) {
57 // std::cerr << "Hep3Vector::rapidity() - "
58 // << "Rapidity in Z direction taken for
59 // << "the log would return a NAN" << std
60 // }
61 // Want inverse std::tanh(dz):
62 return (.5 * std::log((1+z())/(1-z())) );
63 }
64
65 double Hep3Vector::coLinearRapidity() const {
66 double b = beta();
67 // if (b == 1) {
68 // std::cerr << "Hep3Vector::coLinearRapidi
69 // << "Co-linear Rapidity taken for Hep3V
70 // << "the log should return infinity" <<
71 // }
72 // if (b > 1) {
73 // std::cerr << "Hep3Vector::coLinearRapidi
74 // << "Co-linear Rapidity taken for Hep3V
75 // << "the log would return a NAN" << std
76 // }
77 // Want inverse std::tanh(b):
78 return (.5 * std::log((1+b)/(1-b)) );
79 }
80
81 //-*******************************************
82 // Other properties relative to a reference ve
83 //-*******************************************
84
85 Hep3Vector Hep3Vector::project (const Hep3Vect
86 double mag2v2 = v2.mag2();
87 if (mag2v2 == 0) {
88 std::cerr << "Hep3Vector::project() - "
89 << "Attempt to take projection of vector
90 << std::endl;
91 return project();
92 }
93 return ( v2 * (dot(v2)/mag2v2) );
94 }
95
96 double Hep3Vector::rapidity(const Hep3Vector &
97 double vmag = v2.mag();
98 if ( vmag == 0 ) {
99 std::cerr << "Hep3Vector::rapidity() - "
100 << "Rapidity taken with respect to zero
101 return 0;
102 }
103 double z1 = dot(v2)/vmag;
104 // if (std::fabs(z1) >= 1) {
105 // std::cerr << "Hep3Vector::rapidity() - "
106 // << "Rapidity taken for too large a Hep
107 // << "-- would return infinity or NAN" <
108 // }
109 // Want inverse std::tanh(z):
110 return (.5 * std::log((1+z1)/(1-z1)) );
111 }
112
113 double Hep3Vector::eta(const Hep3Vector & v2)
114 // Defined as -std::log ( std::tan ( .5*
115 //
116 // Quicker is to use cosTheta:
117 // std::tan (theta/2) = std::sin(theta)/(1 +
118
119 double r1 = getR();
120 double v2r = v2.mag();
121 if ( (r1 == 0) || (v2r == 0) ) {
122 std::cerr << "Hep3Vector::eta() - "
123 << "Cannot find pseudorapidity of a zero
124 << std::endl;
125 return 0.;
126 }
127 double c = dot(v2)/(r1*v2r);
128 if ( c >= 1 ) {
129 c = 1; //-| We don't want to return NAN b
130 std::cerr << "Hep3Vector::eta() - "
131 << "Pseudorapidity of vector relative to
132 << "will give infinite result" << std::e
133 // We can just go on; tangent will
134 // std::log (tangent) will be -INFIN
135 // will be +INFINITY.
136 }
137 if ( c <= -1 ) {
138 std::cerr << "Hep3Vector::eta() - "
139 << "Pseudorapidity of vector relative to
140 << "will give negative infinite result"<
141 //-| We don't want to return NAN bec
142 return ( negativeInfinity() );
143 // If we just went on, the tangent
144 // so return would be NAN. But the
145 // of tan is +Infinity, so the retur
146 // -INFINITY.
147 }
148
149 double tangent = std::sqrt (1-c*c) / ( 1 + c
150 return (- std::log (tangent));
151
152 } /* eta (u) */
153
154
155 } // namespace CLHEP
156