source: trunk/SISCone/geom_2d.h@ 23

Last change on this file since 23 was 20, checked in by Pavel Demin, 16 years ago

add SISCone library

File size: 5.9 KB
Line 
1// -*- C++ -*-
2///////////////////////////////////////////////////////////////////////////////
3// File: geom_2d.h //
4// Description: header file for two-dimensional geometry tools //
5// This file is part of the SISCone project. //
6// For more details, see http://projects.hepforge.org/siscone //
7// //
8// Copyright (c) 2006 Gavin Salam and Gregory Soyez //
9// //
10// This program is free software; you can redistribute it and/or modify //
11// it under the terms of the GNU General Public License as published by //
12// the Free Software Foundation; either version 2 of the License, or //
13// (at your option) any later version. //
14// //
15// This program is distributed in the hope that it will be useful, //
16// but WITHOUT ANY WARRANTY; without even the implied warranty of //
17// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
18// GNU General Public License for more details. //
19// //
20// You should have received a copy of the GNU General Public License //
21// along with this program; if not, write to the Free Software //
22// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA //
23// //
24// $Revision: 1.1 $//
25// $Date: 2008-10-02 15:20:25 $//
26///////////////////////////////////////////////////////////////////////////////
27
28#ifndef __GEOM_2D_H__
29#define __GEOM_2D_H__
30
31#include <iostream>
32#include <math.h>
33#include "defines.h"
34
35#ifndef M_PI
36#define M_PI 3.141592653589793238462643383279502884197
37#endif
38
39namespace siscone{
40
41/// return a result that corresponds to phi, but in the
42/// range (-pi..pi]; the result is only correct if -3pi < phi <= 3pi
43inline double phi_in_range(double phi) {
44 if (phi <= -M_PI) phi += twopi;
45 else if (phi > M_PI) phi -= twopi;
46 return phi;
47}
48
49/// return the difference between the two phi values,
50/// placed in the correct range (-pi..pi], , assuming that phi1,phi2
51/// are already in the correct range.
52inline double dphi(double phi1, double phi2) {
53 return phi_in_range(phi1-phi2);
54}
55
56
57/// return the absolute difference between the two phi values,
58/// placed in the correct range, assuming that phi1,phi2 are already
59/// in the correct range.
60inline double abs_dphi(double phi1, double phi2) {
61 double delta = fabs(phi1-phi2);
62 return delta > M_PI ? twopi-delta : delta;
63}
64
65/// return the square of the argument
66inline double pow2(double x) {return x*x;}
67
68
69/**
70 * \class Ctwovect
71 * \brief class for holding a two-vector
72 */
73class Ctwovect {
74public:
75 /// default ctor
76 Ctwovect() : x(0.0), y(0.0) {}
77
78 /// ctor with initialisation
79 /// \param _x first coordinate
80 /// \param _y second coordinate
81 Ctwovect(double _x, double _y) : x(_x), y(_y) {}
82
83 /// vector coordinates
84 double x, y;
85
86 /// norm (modulud square) of the vector
87 inline double mod2() const {return pow2(x)+pow2(y);}
88
89 /// modulus of the vector
90 inline double modulus() const {return sqrt(mod2());}
91};
92
93
94/// dot product of two 2-vectors
95/// \param a first 2-vect
96/// \param b second 2-vect
97/// \return a.b is returned
98inline double dot_product(const Ctwovect & a, const Ctwovect & b) {
99 return a.x*b.x + a.y*b.y;
100}
101
102
103/// cross product of two 2-vectors
104/// \param a first 2-vect
105/// \param b second 2-vect
106/// \return a x b is returned
107inline double cross_product(const Ctwovect & a, const Ctwovect & b) {
108 return a.x*b.y - a.y*b.x;
109}
110
111
112/**
113 * \class Ceta_phi_range
114 * \brief class for holding a covering range in eta-phi
115 *
116 * This class deals with ranges in the eta-phi plane. It
117 * implements methods to test if two ranges overlap and
118 * to take the union of two overlapping intervals.
119 */
120class Ceta_phi_range{
121public:
122 /// default ctor
123 Ceta_phi_range();
124
125 /// ctor with initialisation
126 /// we initialise with a centre (in eta,phi) and a radius
127 /// \param c_eta eta coordinate of the centre
128 /// \param c_phi phi coordinate of the centre
129 /// \param R radius
130 Ceta_phi_range(double c_eta, double c_phi, double R);
131
132 /// assignment of range
133 /// \param r range to assign to current one
134 Ceta_phi_range& operator = (const Ceta_phi_range &r);
135
136 /// add a particle to the range
137 /// \param eta eta coordinate of the particle
138 /// \param phi phi coordinate of the particle
139 /// \return 0 on success, 1 on error
140 int add_particle(const double eta, const double phi);
141
142 /// eta range as a binary coding of covered cells
143 unsigned int eta_range;
144
145 /// phi range as a binary coding of covered cells
146 unsigned int phi_range;
147
148 /// maximal value for eta
149 static double eta_min;
150 static double eta_max;
151
152private:
153 /// return the cell index corrsponding to an eta value
154 inline unsigned int get_eta_cell(double eta){
155 return (unsigned int) (1 << ((int) (32*((eta-eta_min)/(eta_max-eta_min)))));
156 }
157
158 /// return the cell index corrsponding to a phi value
159 inline unsigned int get_phi_cell(double phi){
160 return (unsigned int) (1 << ((int) (32*phi/twopi+16)%32));
161 }
162};
163
164/// test overlap
165/// \param r1 first range
166/// \param r2 second range
167/// \return true if overlap, false otherwise.
168bool is_range_overlap(const Ceta_phi_range &r1, const Ceta_phi_range &r2);
169
170/// compute union
171/// Note: we assume that the two intervals overlap
172/// \param r1 first range
173/// \param r2 second range
174/// \return union of the two ranges
175const Ceta_phi_range range_union(const Ceta_phi_range &r1, const Ceta_phi_range &r2);
176
177}
178
179#endif
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