1 | // -*- C++ -*- |
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2 | #ifndef __CLUSTERQUENCE_N2_ICC__ |
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3 | #define __CLUSTERQUENCE_N2_ICC__ |
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4 | #include "fastjet/ClusterSequence.hh" |
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5 | |
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6 | //STARTHEADER |
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7 | // $Id: ClusterSequence_N2.cc 1351 2009-01-09 18:03:03Z salam $ |
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8 | // |
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9 | // Copyright (c) 2005-2009, Matteo Cacciari, Gavin Salam and Gregory Soyez |
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10 | // |
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11 | //---------------------------------------------------------------------- |
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12 | // This file is part of FastJet. |
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13 | // |
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14 | // FastJet is free software; you can redistribute it and/or modify |
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15 | // it under the terms of the GNU General Public License as published by |
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16 | // the Free Software Foundation; either version 2 of the License, or |
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17 | // (at your option) any later version. |
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18 | // |
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19 | // The algorithms that underlie FastJet have required considerable |
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20 | // development and are described in hep-ph/0512210. If you use |
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21 | // FastJet as part of work towards a scientific publication, please |
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22 | // include a citation to the FastJet paper. |
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23 | // |
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24 | // FastJet is distributed in the hope that it will be useful, |
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25 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
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26 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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27 | // GNU General Public License for more details. |
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28 | // |
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29 | // You should have received a copy of the GNU General Public License |
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30 | // along with FastJet; if not, write to the Free Software |
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31 | // Foundation, Inc.: |
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32 | // 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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33 | //---------------------------------------------------------------------- |
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34 | //ENDHEADER |
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35 | |
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36 | //---------------------------------------------------------------------- |
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37 | /// Order(N^2) clustering |
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38 | /// |
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39 | /// Works for any class BJ that satisfies certain minimal |
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40 | /// requirements (which are ...?) |
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41 | /// |
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42 | /// - need to have _bj_set_jetinfo |
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43 | /// - need to have _bj_dist |
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44 | /// - should contain members kt2 (=energy^2), NN, NN_dist, _jets_index |
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45 | |
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46 | FASTJET_BEGIN_NAMESPACE // defined in fastjet/internal/base.hh |
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47 | |
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48 | // this should not normally appear in an include file, but we'll make an |
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49 | // exception seeing as this is |
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50 | //using namespace std; |
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51 | |
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52 | |
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53 | template<class BJ> void ClusterSequence::_simple_N2_cluster() { |
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54 | int n = _jets.size(); |
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55 | BJ * briefjets = new BJ[n]; |
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56 | BJ * jetA = briefjets, * jetB; |
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57 | |
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58 | // initialise the basic jet info |
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59 | for (int i = 0; i< n; i++) { |
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60 | _bj_set_jetinfo(jetA, i); |
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61 | jetA++; // move on to next entry of briefjets |
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62 | } |
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63 | BJ * tail = jetA; // a semaphore for the end of briefjets |
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64 | BJ * head = briefjets; // a nicer way of naming start |
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65 | |
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66 | // now initialise the NN distances: jetA will run from 1..n-1; and |
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67 | // jetB from 0..jetA-1 |
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68 | for (jetA = head + 1; jetA != tail; jetA++) { |
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69 | // set NN info for jetA based on jets running from head..jetA-1, |
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70 | // checking in the process whether jetA itself is an undiscovered |
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71 | // NN of one of those jets. |
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72 | _bj_set_NN_crosscheck(jetA, head, jetA); |
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73 | } |
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74 | |
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75 | |
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76 | // now create the diJ (where J is i's NN) table -- remember that |
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77 | // we differ from standard normalisation here by a factor of R2 |
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78 | double * diJ = new double[n]; |
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79 | jetA = head; |
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80 | for (int i = 0; i < n; i++) { |
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81 | diJ[i] = _bj_diJ(jetA); |
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82 | jetA++; // have jetA follow i |
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83 | } |
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84 | |
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85 | // now run the recombination loop |
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86 | int history_location = n-1; |
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87 | while (tail != head) { |
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88 | |
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89 | // find the minimum of the diJ on this round |
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90 | double diJ_min = diJ[0]; |
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91 | int diJ_min_jet = 0; |
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92 | for (int i = 1; i < n; i++) { |
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93 | if (diJ[i] < diJ_min) {diJ_min_jet = i; diJ_min = diJ[i];} |
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94 | } |
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95 | |
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96 | // do the recombination between A and B |
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97 | history_location++; |
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98 | jetA = & briefjets[diJ_min_jet]; |
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99 | // GPS mod 2009-02-11 |
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100 | //jetB = jetA->NN; |
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101 | jetB = static_cast<BJ *>(jetA->NN); |
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102 | // put the normalisation back in |
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103 | diJ_min *= _invR2; |
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104 | if (jetB != NULL) { |
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105 | // jet-jet recombination |
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106 | // If necessary relabel A & B to ensure jetB < jetA, that way if |
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107 | // the larger of them == newtail then that ends up being jetA and |
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108 | // the new jet that is added as jetB is inserted in a position that |
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109 | // has a future! |
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110 | if (jetA < jetB) {std::swap(jetA,jetB);} |
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111 | |
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112 | int nn; // new jet index |
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113 | _do_ij_recombination_step(jetA->_jets_index, jetB->_jets_index, diJ_min, nn); |
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114 | |
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115 | // what was jetB will now become the new jet |
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116 | _bj_set_jetinfo(jetB, nn); |
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117 | |
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118 | } else { |
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119 | // jet-beam recombination |
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120 | _do_iB_recombination_step(jetA->_jets_index, diJ_min); |
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121 | } |
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122 | |
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123 | // now update our nearest neighbour info and diJ table |
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124 | // first reduce size of table |
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125 | tail--; n--; |
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126 | // Copy last jet contents and diJ info into position of jetA |
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127 | *jetA = *tail; |
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128 | diJ[jetA - head] = diJ[tail-head]; |
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129 | |
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130 | // Initialise jetB's NN distance as well as updating it for |
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131 | // other particles. |
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132 | // NB: by having different loops for jetB == or != NULL we could |
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133 | // perhaps save a few percent (usually avoid one if inside loop), |
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134 | // but will not do it for now because on laptop fluctuations are |
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135 | // too large to reliably measure a few percent difference... |
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136 | for (BJ * jetI = head; jetI != tail; jetI++) { |
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137 | // see if jetI had jetA or jetB as a NN -- if so recalculate the NN |
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138 | if (jetI->NN == jetA || jetI->NN == jetB) { |
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139 | _bj_set_NN_nocross(jetI, head, tail); |
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140 | diJ[jetI-head] = _bj_diJ(jetI); // update diJ |
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141 | } |
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142 | // check whether new jetB is closer than jetI's current NN and |
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143 | // if need be update things |
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144 | if (jetB != NULL) { |
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145 | double dist = _bj_dist(jetI,jetB); |
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146 | if (dist < jetI->NN_dist) { |
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147 | if (jetI != jetB) { |
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148 | jetI->NN_dist = dist; |
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149 | jetI->NN = jetB; |
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150 | diJ[jetI-head] = _bj_diJ(jetI); // update diJ... |
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151 | } |
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152 | } |
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153 | if (dist < jetB->NN_dist) { |
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154 | if (jetI != jetB) { |
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155 | jetB->NN_dist = dist; |
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156 | jetB->NN = jetI;} |
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157 | } |
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158 | } |
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159 | // if jetI's NN is the new tail then relabel it so that it becomes jetA |
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160 | if (jetI->NN == tail) {jetI->NN = jetA;} |
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161 | } |
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162 | |
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163 | |
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164 | if (jetB != NULL) {diJ[jetB-head] = _bj_diJ(jetB);} |
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165 | |
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166 | |
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167 | } |
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168 | |
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169 | |
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170 | // final cleaning up; |
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171 | delete[] diJ; |
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172 | delete[] briefjets; |
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173 | } |
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174 | |
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175 | |
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176 | |
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177 | // //---------------------------------------------------------------------- |
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178 | // // initialises a GenBriefJet |
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179 | // template<> inline void ClusterSequence::_bj_set_jetinfo( |
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180 | // GenBriefJet * const jetA, const int _jets_index) const { |
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181 | // |
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182 | // jetA->init(_jets[_jets_index]); |
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183 | // jetA->_jets_index = _jets_index; |
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184 | // |
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185 | // } |
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186 | // |
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187 | // |
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188 | // //---------------------------------------------------------------------- |
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189 | // // returns the distance between two GenBriefJets |
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190 | // template<> double ClusterSequence::_bj_dist( |
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191 | // const GenBriefJet * const jeta, |
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192 | // const GenBriefJet * const jetb) const { |
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193 | // return jeta->geom_ij(jetb); |
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194 | // } |
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195 | |
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196 | FASTJET_END_NAMESPACE |
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197 | |
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198 | #endif // __CLUSTERQUENCE_N2_ICC__ |
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199 | |
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200 | |
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