HepMC3 event record library
FourVector.h
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1// -*- C++ -*-
2//
3// This file is part of HepMC
4// Copyright (C) 2014-2020 The HepMC collaboration (see AUTHORS for details)
5//
6#ifndef HEPMC3_FOURVECTOR_H
7#define HEPMC3_FOURVECTOR_H
8/**
9 * @file FourVector.h
10 * @brief Definition of \b class FourVector
11 */
12#include <cmath>
13#include <limits>
14#ifndef M_PI
15/** @brief Definition of PI. Needed on some platforms */
16#define M_PI 3.14159265358979323846264338327950288
17#endif
18namespace HepMC3 {
19
20
21/**
22 * @brief Generic 4-vector
23 *
24 * Interpretation of its content depends on accessors used: it's much simpler to do this
25 * than to distinguish between space and momentum vectors via the type system (especially
26 * given the need for backward compatibility with HepMC2). Be sensible and don't call
27 * energy functions on spatial vectors! To avoid duplication, most definitions are only
28 * implemented on the spatial function names, with the energy-momentum functions as aliases.
29 *
30 * This is @a not intended to be a fully featured 4-vector, but does contain the majority
31 * of common non-boosting functionality, as well as a few support operations on
32 * 4-vectors.
33 *
34 * The implementations in this class are fully inlined.
35 */
37public:
38
39 /** @brief Default constructor */
41 : m_v1(0.0), m_v2(0.0), m_v3(0.0), m_v4(0.0) {}
42 /** @brief Sets all FourVector fields */
43 FourVector(double xx, double yy, double zz, double ee)
44 : m_v1(xx), m_v2(yy), m_v3(zz), m_v4(ee) {}
45 /** @brief Copy constructor */
47 : m_v1(v.m_v1), m_v2(v.m_v2), m_v3(v.m_v3), m_v4(v.m_v4) {}
48
49
50 /// @name Component accessors
51 //@{
52
53 /** @brief Set all FourVector fields, in order x,y,z,t */
54 void set(double x1, double x2, double x3, double x4) {
55 m_v1 = x1;
56 m_v2 = x2;
57 m_v3 = x3;
58 m_v4 = x4;
59 }
60
61 /// set component of position/displacement
62 void set_component(const int i, const double x)
63 {
64 if (i==0) {m_v1=x; return; }
65 if (i==1) {m_v2=x; return; }
66 if (i==2) {m_v3=x; return; }
67 if (i==3) {m_v4=x; return; }
68 }
69 /// get component of position/displacement
70 double get_component(const int i) const
71 {
72 if (i==0) return m_v1;
73 if (i==1) return m_v2;
74 if (i==2) return m_v3;
75 if (i==3) return m_v4;
76 return 0.0;
77 }
78
79
80 /// x-component of position/displacement
81 double x() const { return m_v1; }
82 /// Set x-component of position/displacement
83 void set_x(double xx) { m_v1 = xx; }
84 /// @deprecated Prefer the HepMC-style set_x() function
85 void setX(double xx) { set_x(xx); }
86
87 /// y-component of position/displacement
88 double y() const { return m_v2; }
89 /// Set y-component of position/displacement
90 void set_y(double yy) { m_v2 = yy; }
91 /// @deprecated Prefer the HepMC-style set_y() function
92 void setY(double yy) { set_y(yy); }
93
94 /// z-component of position/displacement
95 double z() const { return m_v3; }
96 /// Set z-component of position/displacement
97 void set_z(double zz) { m_v3 = zz; }
98 /// @deprecated Prefer the HepMC-style set_z() function
99 void setZ(double zz) { set_z(zz); }
100
101 /// Time component of position/displacement
102 double t() const { return m_v4; }
103 /// Set time component of position/displacement
104 void set_t(double tt) { m_v4 = tt; }
105 /// @deprecated Prefer the HepMC-style set_t() function
106 void setT(double tt) { set_t(tt); }
107
108
109 /// x-component of momentum
110 double px() const { return x(); }
111 /// Set x-component of momentum
112 void set_px(double pxx) { set_x(pxx); }
113 /// @deprecated Prefer the HepMC-style set_px() function
114 void setPx(double pxx) { set_px(pxx); }
115
116 /// y-component of momentum
117 double py() const { return y(); }
118 /// Set y-component of momentum
119 void set_py(double pyy) { set_y(pyy); }
120 /// @deprecated Prefer the HepMC-style set_py() function
121 void setPy(double pyy) { set_py(pyy); }
122
123 /// z-component of momentum
124 double pz() const { return z(); }
125 /// Set z-component of momentum
126 void set_pz(double pzz) { set_z(pzz); }
127 /// @deprecated Prefer the HepMC-style set_pz() function
128 void setPz(double pzz) { set_pz(pzz); }
129
130 /// Energy component of momentum
131 double e() const { return t(); }
132 /// Set energy component of momentum
133 void set_e(double ee ) { this->set_t(ee); }
134 /// @deprecated Prefer the HepMC-style set_y() function
135 void setE(double ee) { set_e(ee); }
136
137 //@}
138
139
140 /// @name Computed properties
141 //@{
142
143 /// Squared magnitude of (x, y, z) 3-vector
144 double length2() const { return x()*x() + y()*y() + z()*z(); }
145 /// Magnitude of spatial (x, y, z) 3-vector
146 double length() const { return std::sqrt(length2()); }
147 /// Squared magnitude of (x, y) vector
148 double perp2() const { return x()*x() + y()*y(); }
149 /// Magnitude of (x, y) vector
150 double perp() const { return std::sqrt(perp2()); }
151 /// Spacetime invariant interval s^2 = t^2 - x^2 - y^2 - z^2
152 double interval() const { return t()*t() - length2(); }
153
154 /// Squared magnitude of p3 = (px, py, pz) vector
155 double p3mod2() const { return length2(); }
156 /// Magnitude of p3 = (px, py, pz) vector
157 double p3mod() const { return length(); }
158 /// Squared transverse momentum px^2 + py^2
159 double pt2() const { return perp2(); }
160 /// Transverse momentum
161 double pt() const { return perp(); }
162 /// Squared invariant mass m^2 = E^2 - px^2 - py^2 - pz^2
163 double m2() const { return interval(); }
164 /// Invariant mass. Returns -sqrt(-m) if e^2 - P^2 is negative
165 double m() const { return (m2() > 0.0) ? std::sqrt(m2()) : -std::sqrt(-m2()); }
166
167 /// Azimuthal angle
168 double phi() const { return std::atan2( y(), x() ); }
169 /// Polar angle w.r.t. z direction
170 double theta() const { return std::atan2( perp(), z() ); }
171 /// Pseudorapidity
172 double eta() const { return ( p3mod() == 0.0 ) ? 0.0: (0.5*std::log( (p3mod() + pz()) / (p3mod() - pz()) )); }
173 /// Rapidity
174 double rap() const { return ( e() == 0.0 ) ? 0.0: (0.5*std::log( (e() + pz()) / (e() - pz()) )); }
175 /// Absolute pseudorapidity
176 double abs_eta() const { return std::abs( eta() ); }
177 /// Absolute rapidity
178 double abs_rap() const { return std::abs( rap() ); }
179
180 /// Same as eta()
181 /// @deprecated Prefer 'only one way to do it', and we don't have equivalent long names for e.g. pid, phi or eta
182 double pseudoRapidity() const { return eta(); }
183
184 //@}
185
186
187 /// @name Comparisons to another FourVector
188 //@{
189
190 /// Check if the length of this vertex is zero
191 bool is_zero() const { return x() == 0 && y() == 0 && z() == 0 && t() == 0; }
192
193 /// Signed azimuthal angle separation in [-pi, pi]
194 double delta_phi(const FourVector &v) const {
195 double dphi = phi() - v.phi();
196 if (dphi != dphi) return dphi;
197 while (dphi >= M_PI) dphi -= 2.*M_PI;
198 while (dphi < -M_PI) dphi += 2.*M_PI;
199 return dphi;
200 }
201
202 /// Pseudorapidity separation
203 double delta_eta(const FourVector &v) const { return eta() - v.eta(); }
204
205 /// Rapidity separation
206 double delta_rap(const FourVector &v) const { return rap() - v.rap(); }
207
208 /// R_eta^2-distance separation dR^2 = dphi^2 + deta^2
209 double delta_r2_eta(const FourVector &v) const {
210 return delta_phi(v)*delta_phi(v) + delta_eta(v)*delta_eta(v);
211 }
212
213 /// R_eta-distance separation dR = sqrt(dphi^2 + deta^2)
214 double delta_r_eta(const FourVector &v) const {
215 return std::sqrt( delta_r2_eta(v) );
216 }
217
218 /// R_rap^2-distance separation dR^2 = dphi^2 + drap^2
219 double delta_r2_rap(const FourVector &v) const {
220 return delta_phi(v)*delta_phi(v) + delta_rap(v)*delta_rap(v);
221 }
222
223 /// R-rap-distance separation dR = sqrt(dphi^2 + drap^2)
224 double delta_r_rap(const FourVector &v) const {
225 return std::sqrt( delta_r2_rap(v) );
226 }
227
228 //@}
229
230
231 /// @name Operators
232 //@{
233
234 /// Equality
235 bool operator==(const FourVector& rhs) const {
236 return x() == rhs.x() && y() == rhs.y() && z() == rhs.z() && t() == rhs.t();
237 }
238 /// Inequality
239 bool operator!=(const FourVector& rhs) const { return !(*this == rhs); }
240
241 /// Arithmetic operator +
242 FourVector operator+ (const FourVector& rhs) const {
243 return FourVector( x() + rhs.x(), y() + rhs.y(), z() + rhs.z(), t() + rhs.t() );
244 }
245 /// Arithmetic operator -
246 FourVector operator- (const FourVector& rhs) const {
247 return FourVector( x() - rhs.x(), y() - rhs.y(), z() - rhs.z(), t() - rhs.t() );
248 }
249 /// Arithmetic operator * by scalar
250 FourVector operator* (const double rhs) const {
251 return FourVector( x()*rhs, y()*rhs, z()*rhs, t()*rhs );
252 }
253 /// Arithmetic operator / by scalar
254 FourVector operator/ (const double rhs) const {
255 return FourVector( x()/rhs, y()/rhs, z()/rhs, t()/rhs );
256 }
257
258 /// Arithmetic operator +=
259 void operator += (const FourVector& rhs) {
260 setX(x() + rhs.x());
261 setY(y() + rhs.y());
262 setZ(z() + rhs.z());
263 setT(t() + rhs.t());
264 }
265 /// Arithmetic operator -=
266 void operator -= (const FourVector& rhs) {
267 setX(x() - rhs.x());
268 setY(y() - rhs.y());
269 setZ(z() - rhs.z());
270 setT(t() - rhs.t());
271 }
272 /// Arithmetic operator *= by scalar
273 void operator *= (const double rhs) {
274 setX(x()*rhs);
275 setY(y()*rhs);
276 setZ(z()*rhs);
277 setT(t()*rhs);
278 }
279 /// Arithmetic operator /= by scalar
280 void operator /= (const double rhs) {
281 setX(x()/rhs);
282 setY(y()/rhs);
283 setZ(z()/rhs);
284 setT(t()/rhs);
285 }
286
287 //@}
288
289
290 /// Static null FourVector = (0,0,0,0)
291 static const FourVector& ZERO_VECTOR() {
292 static const FourVector v;
293 return v;
294 }
295
296
297private:
298
299 double m_v1; ///< px or x. Interpretation depends on accessors used
300 double m_v2; ///< py or y. Interpretation depends on accessors used
301 double m_v3; ///< pz or z. Interpretation depends on accessors used
302 double m_v4; ///< e or t. Interpretation depends on accessors used
303
304};
305
306
307/// @name Unbound vector comparison functions
308//@{
309
310/// Signed azimuthal angle separation in [-pi, pi] between vecs @c a and @c b
311inline double delta_phi(const FourVector &a, const FourVector &b) { return b.delta_phi(a); }
312
313/// Pseudorapidity separation between vecs @c a and @c b
314inline double delta_eta(const FourVector &a, const FourVector &b) { return b.delta_eta(a); }
315
316/// Rapidity separation between vecs @c a and @c b
317inline double delta_rap(const FourVector &a, const FourVector &b) { return b.delta_rap(a); }
318
319/// R_eta^2-distance separation dR^2 = dphi^2 + deta^2 between vecs @c a and @c b
320inline double delta_r2_eta(const FourVector &a, const FourVector &b) { return b.delta_r2_eta(a); }
321
322/// R_eta-distance separation dR = sqrt(dphi^2 + deta^2) between vecs @c a and @c b
323inline double delta_r_eta(const FourVector &a, const FourVector &b) { return b.delta_r_eta(a); }
324
325/// R_rap^2-distance separation dR^2 = dphi^2 + drap^2 between vecs @c a and @c b
326inline double delta_r2_rap(const FourVector &a, const FourVector &b) { return b.delta_r2_rap(a); }
327
328/// R_rap-distance separation dR = sqrt(dphi^2 + drap^2) between vecs @c a and @c b
329inline double delta_r_rap(const FourVector &a, const FourVector &b) { return b.delta_r_rap(a); }
330
331//@}
332
333
334} // namespace HepMC3
335#endif
#define M_PI
Definition of PI. Needed on some platforms.
Definition: FourVector.h:16
Generic 4-vector.
Definition: FourVector.h:36
void setE(double ee)
Definition: FourVector.h:135
double pt2() const
Squared transverse momentum px^2 + py^2.
Definition: FourVector.h:159
void set_t(double tt)
Set time component of position/displacement.
Definition: FourVector.h:104
double e() const
Energy component of momentum.
Definition: FourVector.h:131
void setT(double tt)
Definition: FourVector.h:106
FourVector()
Default constructor.
Definition: FourVector.h:40
double p3mod() const
Magnitude of p3 = (px, py, pz) vector.
Definition: FourVector.h:157
double pz() const
z-component of momentum
Definition: FourVector.h:124
double t() const
Time component of position/displacement.
Definition: FourVector.h:102
double m2() const
Squared invariant mass m^2 = E^2 - px^2 - py^2 - pz^2.
Definition: FourVector.h:163
double interval() const
Spacetime invariant interval s^2 = t^2 - x^2 - y^2 - z^2.
Definition: FourVector.h:152
double delta_r_eta(const FourVector &v) const
R_eta-distance separation dR = sqrt(dphi^2 + deta^2)
Definition: FourVector.h:214
bool is_zero() const
Check if the length of this vertex is zero.
Definition: FourVector.h:191
double m_v4
e or t. Interpretation depends on accessors used
Definition: FourVector.h:302
double m_v3
pz or z. Interpretation depends on accessors used
Definition: FourVector.h:301
double m_v2
py or y. Interpretation depends on accessors used
Definition: FourVector.h:300
void set_x(double xx)
Set x-component of position/displacement.
Definition: FourVector.h:83
void setPz(double pzz)
Definition: FourVector.h:128
void set_px(double pxx)
Set x-component of momentum.
Definition: FourVector.h:112
double eta() const
Pseudorapidity.
Definition: FourVector.h:172
void setY(double yy)
Definition: FourVector.h:92
void setPy(double pyy)
Definition: FourVector.h:121
double px() const
x-component of momentum
Definition: FourVector.h:110
double delta_r2_eta(const FourVector &v) const
R_eta^2-distance separation dR^2 = dphi^2 + deta^2.
Definition: FourVector.h:209
double delta_r2_rap(const FourVector &v) const
R_rap^2-distance separation dR^2 = dphi^2 + drap^2.
Definition: FourVector.h:219
void operator*=(const double rhs)
Arithmetic operator *= by scalar.
Definition: FourVector.h:273
bool operator==(const FourVector &rhs) const
Equality.
Definition: FourVector.h:235
double abs_rap() const
Absolute rapidity.
Definition: FourVector.h:178
double py() const
y-component of momentum
Definition: FourVector.h:117
void setX(double xx)
Definition: FourVector.h:85
void set_pz(double pzz)
Set z-component of momentum.
Definition: FourVector.h:126
static const FourVector & ZERO_VECTOR()
Static null FourVector = (0,0,0,0)
Definition: FourVector.h:291
void operator-=(const FourVector &rhs)
Arithmetic operator -=.
Definition: FourVector.h:266
double delta_phi(const FourVector &v) const
Signed azimuthal angle separation in [-pi, pi].
Definition: FourVector.h:194
void operator+=(const FourVector &rhs)
Arithmetic operator +=.
Definition: FourVector.h:259
void operator/=(const double rhs)
Arithmetic operator /= by scalar.
Definition: FourVector.h:280
double length() const
Magnitude of spatial (x, y, z) 3-vector.
Definition: FourVector.h:146
double x() const
x-component of position/displacement
Definition: FourVector.h:81
double perp2() const
Squared magnitude of (x, y) vector.
Definition: FourVector.h:148
double delta_r_rap(const FourVector &v) const
R-rap-distance separation dR = sqrt(dphi^2 + drap^2)
Definition: FourVector.h:224
double pt() const
Transverse momentum.
Definition: FourVector.h:161
FourVector(const FourVector &v)
Copy constructor.
Definition: FourVector.h:46
FourVector(double xx, double yy, double zz, double ee)
Sets all FourVector fields.
Definition: FourVector.h:43
FourVector operator-(const FourVector &rhs) const
Arithmetic operator -.
Definition: FourVector.h:246
double p3mod2() const
Squared magnitude of p3 = (px, py, pz) vector.
Definition: FourVector.h:155
double pseudoRapidity() const
Definition: FourVector.h:182
double phi() const
Azimuthal angle.
Definition: FourVector.h:168
double delta_rap(const FourVector &v) const
Rapidity separation.
Definition: FourVector.h:206
double abs_eta() const
Absolute pseudorapidity.
Definition: FourVector.h:176
double length2() const
Squared magnitude of (x, y, z) 3-vector.
Definition: FourVector.h:144
double m() const
Invariant mass. Returns -sqrt(-m) if e^2 - P^2 is negative.
Definition: FourVector.h:165
double get_component(const int i) const
get component of position/displacement
Definition: FourVector.h:70
double perp() const
Magnitude of (x, y) vector.
Definition: FourVector.h:150
double y() const
y-component of position/displacement
Definition: FourVector.h:88
bool operator!=(const FourVector &rhs) const
Inequality.
Definition: FourVector.h:239
void set_z(double zz)
Set z-component of position/displacement.
Definition: FourVector.h:97
void set_component(const int i, const double x)
set component of position/displacement
Definition: FourVector.h:62
FourVector operator*(const double rhs) const
Arithmetic operator * by scalar.
Definition: FourVector.h:250
double m_v1
px or x. Interpretation depends on accessors used
Definition: FourVector.h:299
void set(double x1, double x2, double x3, double x4)
Set all FourVector fields, in order x,y,z,t.
Definition: FourVector.h:54
void setPx(double pxx)
Definition: FourVector.h:114
double z() const
z-component of position/displacement
Definition: FourVector.h:95
double delta_eta(const FourVector &v) const
Pseudorapidity separation.
Definition: FourVector.h:203
double rap() const
Rapidity.
Definition: FourVector.h:174
void set_y(double yy)
Set y-component of position/displacement.
Definition: FourVector.h:90
void set_e(double ee)
Set energy component of momentum.
Definition: FourVector.h:133
double theta() const
Polar angle w.r.t. z direction.
Definition: FourVector.h:170
void setZ(double zz)
Definition: FourVector.h:99
FourVector operator/(const double rhs) const
Arithmetic operator / by scalar.
Definition: FourVector.h:254
void set_py(double pyy)
Set y-component of momentum.
Definition: FourVector.h:119
FourVector operator+(const FourVector &rhs) const
Arithmetic operator +.
Definition: FourVector.h:242
HepMC3 main namespace.
double delta_eta(const FourVector &a, const FourVector &b)
Pseudorapidity separation between vecs a and b.
Definition: FourVector.h:314
double delta_r2_rap(const FourVector &a, const FourVector &b)
R_rap^2-distance separation dR^2 = dphi^2 + drap^2 between vecs a and b.
Definition: FourVector.h:326
double delta_r2_eta(const FourVector &a, const FourVector &b)
R_eta^2-distance separation dR^2 = dphi^2 + deta^2 between vecs a and b.
Definition: FourVector.h:320
double delta_rap(const FourVector &a, const FourVector &b)
Rapidity separation between vecs a and b.
Definition: FourVector.h:317
double delta_r_eta(const FourVector &a, const FourVector &b)
R_eta-distance separation dR = sqrt(dphi^2 + deta^2) between vecs a and b.
Definition: FourVector.h:323
double delta_r_rap(const FourVector &a, const FourVector &b)
R_rap-distance separation dR = sqrt(dphi^2 + drap^2) between vecs a and b.
Definition: FourVector.h:329
Feature< Feature_type > abs(const Feature< Feature_type > &input)
Obtain the absolute value of a Feature. This works as you'd expect. If foo is a valid Feature,...
Definition: Feature.h:323
double delta_phi(const FourVector &a, const FourVector &b)
Signed azimuthal angle separation in [-pi, pi] between vecs a and b.
Definition: FourVector.h:311