1 | #ifndef INLINE_MATHS |
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2 | #define INLINE_MATHS |
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3 | |
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4 | // This file is distributed with FastJet under the terms of the GNU |
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5 | // General Public License (v2). Permission to do so has been granted |
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6 | // by Lars Sonnenschein and the D0 collaboration (see COPYING for |
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7 | // details) |
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8 | // |
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9 | // History of changes in FastJet compared tothe original version of |
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10 | // inline_math.h |
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11 | // |
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12 | // 2011-12-13 Gregory Soyez <soyez@fastjet.fr> |
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13 | // |
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14 | // * added license information |
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15 | // |
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16 | // 2011-10-06 Gregory Soyez <soyez@fastjet.fr> |
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17 | // |
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18 | // * put the code in the fastjet::d0runi namespace |
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19 | |
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20 | #include <cmath> |
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21 | #include <cerrno> |
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22 | #include <fastjet/internal/base.hh> |
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23 | |
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24 | FASTJET_BEGIN_NAMESPACE |
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25 | |
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26 | //using namespace std; |
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27 | |
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28 | namespace d0runi{ |
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29 | namespace inline_maths { |
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30 | |
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31 | const double PI = fabs(acos(-1.)); |
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32 | |
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33 | const double TWOPI = 2*PI; |
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34 | |
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35 | |
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36 | inline double sqr(double a) { |
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37 | return a*a; |
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38 | } |
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39 | |
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40 | |
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41 | |
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42 | inline double min(double a, double b) { |
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43 | return (a < b) ? a : b; |
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44 | } |
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45 | |
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46 | |
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47 | |
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48 | inline double delta_phi(double phi1, double phi2) { |
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49 | double dphi = min( double(fabs(phi1-phi2)), double(2.*PI-fabs(phi1-phi2)) ); |
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50 | return (phi1 < phi2) ? -dphi : dphi; |
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51 | } |
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52 | |
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53 | |
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54 | |
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55 | inline double phi(double px, double py) { |
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56 | return atan2(py, px); |
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57 | } |
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58 | |
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59 | |
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60 | |
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61 | inline double y(double E, double pz) { |
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62 | errno=0; |
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63 | double y; |
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64 | //cout << "inline_maths: "; |
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65 | if (fabs(E-pz) == 0.) { |
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66 | // cout << "Error in header mathe.h: division by 0 in function y!" << " p=" << p << " pz=" << pz << endl; |
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67 | // exit(721); |
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68 | errno=721; |
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69 | y = 99999.; |
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70 | } |
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71 | else { |
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72 | y = 0.5*log((E+pz)/(E-pz)); |
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73 | } |
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74 | //cout << "y: E=" << E << " pz=" << pz << " y=" << y << endl; |
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75 | return y; |
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76 | } |
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77 | |
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78 | |
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79 | |
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80 | |
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81 | inline double eta(double p, double pz) { |
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82 | errno=0; |
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83 | double eta; |
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84 | //cout << "inline_maths: "; |
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85 | if (fabs(p-pz) == 0.) { |
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86 | // cout << "Error in header mathe.h: division by 0 in function eta!" << " p=" << p << " pz=" << pz << endl; |
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87 | // exit(721); |
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88 | errno=721; |
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89 | eta = 99999.; |
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90 | } |
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91 | else { |
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92 | eta = 0.5*log((p+pz)/(p-pz)); |
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93 | } |
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94 | //cout << "eta: p=" << p << " pz=" << pz << " eta=" << eta << endl; |
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95 | return eta; |
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96 | } |
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97 | |
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98 | |
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99 | |
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100 | |
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101 | inline double eta(double px, double py, double pz) { |
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102 | errno=0; |
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103 | double eta; |
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104 | //cout << "inline_maths: "; |
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105 | double p = sqrt(px*px+py*py+pz*pz); |
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106 | if (fabs(p-pz) == 0.) { |
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107 | // cout << "Error in header mathe.h: division by 0 in function eta!" << " p=" << p << " pz=" << pz << endl; |
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108 | // exit(721); |
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109 | errno=721; |
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110 | eta = 99999.; |
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111 | } |
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112 | else { |
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113 | eta = 0.5*log((p+pz)/(p-pz)); |
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114 | } |
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115 | //cout << "eta: p=" << p << " pz=" << pz << " eta=" << eta << endl; |
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116 | return eta; |
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117 | } |
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118 | |
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119 | |
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120 | |
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121 | inline double eta(double theta) { |
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122 | double eta = -log(tan(theta/2.)); |
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123 | |
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124 | return eta; |
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125 | } |
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126 | |
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127 | |
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128 | inline double theta(double eta) { |
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129 | double theta = 2.*atan(exp(-eta)); |
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130 | |
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131 | return theta; |
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132 | } |
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133 | |
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134 | inline double theta(double px, double py, double pz) { |
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135 | double Eta = eta(px, py, pz); |
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136 | double theta = 2.*atan(exp(-Eta)); |
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137 | |
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138 | return theta; |
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139 | } |
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140 | |
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141 | |
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142 | |
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143 | } //end usename inline_maths |
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144 | } //end usename d0runi |
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145 | |
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146 | FASTJET_END_NAMESPACE |
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147 | |
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148 | |
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149 | #endif |
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