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25 // 25 //
26 // 26 //
27 // 27 //
28 // 28 //
29 // ------------------------------------------- 29 // ---------------------------------------------------------------------------
30 // GEANT 4 class header file 30 // GEANT 4 class header file
31 // ------------------------------------------- 31 // ---------------------------------------------------------------------------
32 // Class description: 32 // Class description:
33 // 33 //
34 // Utility functions 34 // Utility functions
35 35
36 // History: 36 // History:
37 // 37 //
38 // 24.08.17 - E.Tcherniaev, added G4RandomRadi 38 // 24.08.17 - E.Tcherniaev, added G4RandomRadiusInRing, G4RandomPointInEllipse
39 // G4RandomPointOnEll 39 // G4RandomPointOnEllipse, G4RandomPointOnEllipsoid
40 // 07.11.08 - P.Gumplinger, based on implement 40 // 07.11.08 - P.Gumplinger, based on implementation in G4OpBoundaryProcess
41 // 41 //
42 // ------------------------------------------- 42 // ---------------------------------------------------------------------------
43 43
44 #ifndef G4RANDOMTOOLS_HH 44 #ifndef G4RANDOMTOOLS_HH
45 #define G4RANDOMTOOLS_HH 45 #define G4RANDOMTOOLS_HH
46 46
47 #include <CLHEP/Units/PhysicalConstants.h> 47 #include <CLHEP/Units/PhysicalConstants.h>
48 48
49 #include "G4RandomDirection.hh" 49 #include "G4RandomDirection.hh"
50 #include "G4ThreeVector.hh" 50 #include "G4ThreeVector.hh"
51 #include "G4TwoVector.hh" 51 #include "G4TwoVector.hh"
52 #include "Randomize.hh" 52 #include "Randomize.hh"
53 #include "globals.hh" 53 #include "globals.hh"
54 54
55 // ------------------------------------------- 55 // ---------------------------------------------------------------------------
56 // Returns a random lambertian unit vector (re 56 // Returns a random lambertian unit vector (rejection sampling)
57 // 57 //
58 inline G4ThreeVector G4LambertianRand(const G4 58 inline G4ThreeVector G4LambertianRand(const G4ThreeVector& normal)
59 { 59 {
60 G4ThreeVector vect; 60 G4ThreeVector vect;
61 G4double ndotv; 61 G4double ndotv;
62 G4int count = 0; 62 G4int count = 0;
63 const G4int max_trials = 1024; 63 const G4int max_trials = 1024;
64 64
65 do 65 do
66 { 66 {
67 ++count; 67 ++count;
68 vect = G4RandomDirection(); 68 vect = G4RandomDirection();
69 ndotv = normal * vect; 69 ndotv = normal * vect;
70 70
71 if(ndotv < 0.0) 71 if(ndotv < 0.0)
72 { 72 {
73 vect = -vect; 73 vect = -vect;
74 ndotv = -ndotv; 74 ndotv = -ndotv;
75 } 75 }
76 76
77 } while(!(G4UniformRand() < ndotv) && (count 77 } while(!(G4UniformRand() < ndotv) && (count < max_trials));
78 78
79 return vect; 79 return vect;
80 } 80 }
81 81
82 // ------------------------------------------- 82 // ---------------------------------------------------------------------------
83 // Chooses a random vector within a plane give 83 // Chooses a random vector within a plane given by the unit normal
84 // 84 //
85 inline G4ThreeVector G4PlaneVectorRand(const G 85 inline G4ThreeVector G4PlaneVectorRand(const G4ThreeVector& normal)
86 { 86 {
87 G4ThreeVector vec1 = normal.orthogonal(); 87 G4ThreeVector vec1 = normal.orthogonal();
88 G4ThreeVector vec2 = vec1.cross(normal); 88 G4ThreeVector vec2 = vec1.cross(normal);
89 89
90 G4double phi = CLHEP::twopi * G4UniformRa 90 G4double phi = CLHEP::twopi * G4UniformRand();
91 G4double cosphi = std::cos(phi); 91 G4double cosphi = std::cos(phi);
92 G4double sinphi = std::sin(phi); 92 G4double sinphi = std::sin(phi);
93 93
94 return cosphi * vec1 + sinphi * vec2; 94 return cosphi * vec1 + sinphi * vec2;
95 } 95 }
96 96
97 // ------------------------------------------- 97 // ---------------------------------------------------------------------------
98 // Returns a random radius in annular ring 98 // Returns a random radius in annular ring
99 // 99 //
100 inline G4double G4RandomRadiusInRing(G4double 100 inline G4double G4RandomRadiusInRing(G4double rmin, G4double rmax)
101 { 101 {
102 if(rmin == rmax) 102 if(rmin == rmax)
103 { 103 {
104 return rmin; 104 return rmin;
105 } 105 }
106 G4double k = G4UniformRand(); 106 G4double k = G4UniformRand();
107 return (rmin <= 0) ? rmax * std::sqrt(k) 107 return (rmin <= 0) ? rmax * std::sqrt(k)
108 : std::sqrt(k * rmax * rm 108 : std::sqrt(k * rmax * rmax + (1. - k) * rmin * rmin);
109 } 109 }
110 110
111 // ------------------------------------------- 111 // ---------------------------------------------------------------------------
112 // Returns a random point in ellipse (x/a)^2 + 112 // Returns a random point in ellipse (x/a)^2 + (y/b)^2 = 1
113 // (rejection sampling) 113 // (rejection sampling)
114 // 114 //
115 inline G4TwoVector G4RandomPointInEllipse(G4do 115 inline G4TwoVector G4RandomPointInEllipse(G4double a, G4double b)
116 { 116 {
117 G4double aa = (a * a == 0) ? 0 : 1 / (a * a) 117 G4double aa = (a * a == 0) ? 0 : 1 / (a * a);
118 G4double bb = (b * b == 0) ? 0 : 1 / (b * b) 118 G4double bb = (b * b == 0) ? 0 : 1 / (b * b);
119 for(G4int i = 0; i < 1000; ++i) 119 for(G4int i = 0; i < 1000; ++i)
120 { 120 {
121 G4double x = a * (2 * G4UniformRand() - 1) 121 G4double x = a * (2 * G4UniformRand() - 1);
122 G4double y = b * (2 * G4UniformRand() - 1) 122 G4double y = b * (2 * G4UniformRand() - 1);
123 if(x * x * aa + y * y * bb <= 1) 123 if(x * x * aa + y * y * bb <= 1)
124 return G4TwoVector(x, y); 124 return G4TwoVector(x, y);
125 } 125 }
126 return G4TwoVector(0, 0); 126 return G4TwoVector(0, 0);
127 } 127 }
128 128
129 // ------------------------------------------- 129 // ---------------------------------------------------------------------------
130 // Returns a random point on ellipse (x/a)^2 + 130 // Returns a random point on ellipse (x/a)^2 + (y/b)^2 = 1
131 // (rejection sampling) 131 // (rejection sampling)
132 // 132 //
133 inline G4TwoVector G4RandomPointOnEllipse(G4do 133 inline G4TwoVector G4RandomPointOnEllipse(G4double a, G4double b)
134 { 134 {
135 G4double A = std::abs(a); 135 G4double A = std::abs(a);
136 G4double B = std::abs(b); 136 G4double B = std::abs(b);
137 G4double mu_max = std::max(A, B); 137 G4double mu_max = std::max(A, B);
138 138
139 G4double x, y; 139 G4double x, y;
140 for(G4int i = 0; i < 1000; ++i) 140 for(G4int i = 0; i < 1000; ++i)
141 { 141 {
142 G4double phi = CLHEP::twopi * G4UniformRan 142 G4double phi = CLHEP::twopi * G4UniformRand();
143 x = std::cos(phi); 143 x = std::cos(phi);
144 y = std::sin(phi); 144 y = std::sin(phi);
145 G4double mu = std::sqrt((B * x) * (B * x) 145 G4double mu = std::sqrt((B * x) * (B * x) + (A * y) * (A * y));
146 if(mu_max * G4UniformRand() <= mu) 146 if(mu_max * G4UniformRand() <= mu)
147 break; 147 break;
148 } 148 }
149 return G4TwoVector(A * x, B * y); 149 return G4TwoVector(A * x, B * y);
150 } 150 }
151 151
152 // ------------------------------------------- 152 // ---------------------------------------------------------------------------
153 // Returns a random point on ellipsoid (x/a)^2 153 // Returns a random point on ellipsoid (x/a)^2 + (y/b)^2 + (z/c)^2 = 1
154 // (rejection sampling) 154 // (rejection sampling)
155 // 155 //
156 inline G4ThreeVector G4RandomPointOnEllipsoid( 156 inline G4ThreeVector G4RandomPointOnEllipsoid(G4double a, G4double b,
157 157 G4double c)
158 { 158 {
159 G4double A = std::abs(a); 159 G4double A = std::abs(a);
160 G4double B = std::abs(b); 160 G4double B = std::abs(b);
161 G4double C = std::abs(c); 161 G4double C = std::abs(c);
162 G4double mu_max = std::max(std::max(A * B, A 162 G4double mu_max = std::max(std::max(A * B, A * C), B * C);
163 163
164 G4ThreeVector p; 164 G4ThreeVector p;
165 for(G4int i = 0; i < 1000; ++i) 165 for(G4int i = 0; i < 1000; ++i)
166 { 166 {
167 p = G4RandomDirection(); 167 p = G4RandomDirection();
168 G4double xbc = p.x() * B * C; 168 G4double xbc = p.x() * B * C;
169 G4double yac = p.y() * A * C; 169 G4double yac = p.y() * A * C;
170 G4double zab = p.z() * A * B; 170 G4double zab = p.z() * A * B;
171 G4double mu = std::sqrt(xbc * xbc + yac * 171 G4double mu = std::sqrt(xbc * xbc + yac * yac + zab * zab);
172 if(mu_max * G4UniformRand() <= mu) 172 if(mu_max * G4UniformRand() <= mu)
173 break; 173 break;
174 } 174 }
175 return G4ThreeVector(A * p.x(), B * p.y(), C 175 return G4ThreeVector(A * p.x(), B * p.y(), C * p.z());
176 } 176 }
177 177
178 #endif /* G4RANDOMTOOLS_HH */ 178 #endif /* G4RANDOMTOOLS_HH */
179 179