1 | //STARTHEADER |
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2 | // $Id: ClusterSequence_CP2DChan.cc 859 2012-11-28 01:49:23Z pavel $ |
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3 | // |
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4 | // Copyright (c) 2005-2011, Matteo Cacciari, Gavin P. Salam and Gregory Soyez |
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5 | // |
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6 | //---------------------------------------------------------------------- |
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7 | // This file is part of FastJet. |
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8 | // |
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9 | // FastJet is free software; you can redistribute it and/or modify |
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10 | // it under the terms of the GNU General Public License as published by |
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11 | // the Free Software Foundation; either version 2 of the License, or |
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12 | // (at your option) any later version. |
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13 | // |
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14 | // The algorithms that underlie FastJet have required considerable |
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15 | // development and are described in hep-ph/0512210. If you use |
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16 | // FastJet as part of work towards a scientific publication, please |
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17 | // include a citation to the FastJet paper. |
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18 | // |
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19 | // FastJet is distributed in the hope that it will be useful, |
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20 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
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21 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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22 | // GNU General Public License for more details. |
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23 | // |
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24 | // You should have received a copy of the GNU General Public License |
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25 | // along with FastJet. If not, see <http://www.gnu.org/licenses/>. |
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26 | //---------------------------------------------------------------------- |
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27 | //ENDHEADER |
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28 | |
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29 | #include "fastjet/ClusterSequence.hh" |
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30 | #include "fastjet/internal/ClosestPair2D.hh" |
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31 | #include<limits> |
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32 | #include<vector> |
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33 | #include<cmath> |
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34 | #include<iostream> |
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35 | |
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36 | FASTJET_BEGIN_NAMESPACE // defined in fastjet/internal/base.hh |
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37 | |
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38 | using namespace std; |
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39 | |
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40 | // place for things we don't want outside world to run into |
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41 | namespace Private { |
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42 | /// class for helping us deal with mirror-image particles. |
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43 | class MirrorInfo{ |
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44 | public: |
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45 | int orig, mirror; |
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46 | MirrorInfo(int a, int b) : orig(a), mirror(b) {}; |
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47 | MirrorInfo() {}; |
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48 | }; |
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49 | |
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50 | /// if there is a need for a mirror when looking for closest pairs |
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51 | /// up to distance D, then return true and turn the supplied point |
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52 | /// into its mirror copy |
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53 | bool make_mirror(Coord2D & point, double Dlim) { |
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54 | if (point.y < Dlim) {point.y += twopi; return true;} |
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55 | if (twopi-point.y < Dlim) {point.y -= twopi; return true;} |
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56 | return false; |
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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 | using namespace Private; |
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62 | |
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63 | |
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64 | //---------------------------------------------------------------------- |
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65 | /// clusters only up to a distance Dlim -- does not deal with "inclusive" jets |
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66 | /// -- these are left to some other part of the program |
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67 | void ClusterSequence::_CP2DChan_limited_cluster (double Dlim) { |
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68 | |
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69 | unsigned int n = _initial_n; |
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70 | |
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71 | vector<MirrorInfo> coordIDs(2*n); // coord IDs of a given jetID |
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72 | vector<int> jetIDs(2*n); // jet ID for a given coord ID |
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73 | vector<Coord2D> coords(2*n); // our coordinates (and copies) |
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74 | |
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75 | // particles within a distance Dlim of the phi edges (phi<Dlim || |
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76 | // phi>2pi-Dli;) will be mirrored. For Dlim>pi, this could lead to |
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77 | // particles copies outside the fixed range in phi which is |
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78 | // [-pi:3pi] (see make_mirror above). Since in that case all |
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79 | // particles get copied anywaym we can just copy particles up to a |
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80 | // distance "pi" from the edges |
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81 | double Dlim4mirror = min(Dlim,pi); |
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82 | |
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83 | // start things off... |
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84 | double minrap = numeric_limits<double>::max(); |
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85 | double maxrap = -minrap; |
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86 | int coord_index = -1; |
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87 | int n_active = 0; |
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88 | for (unsigned jet_i = 0; jet_i < _jets.size(); jet_i++) { |
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89 | |
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90 | // skip jets that already have children or that have infinite |
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91 | // rapidity |
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92 | if (_history[_jets[jet_i].cluster_hist_index()].child != Invalid || |
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93 | (_jets[jet_i].E() == abs(_jets[jet_i].pz()) && |
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94 | _jets[jet_i].perp2() == 0.0) |
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95 | ) {continue;} |
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96 | |
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97 | n_active++; |
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98 | |
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99 | coordIDs[jet_i].orig = ++coord_index; |
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100 | coords[coord_index] = Coord2D(_jets[jet_i].rap(), _jets[jet_i].phi_02pi()); |
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101 | jetIDs[coord_index] = jet_i; |
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102 | minrap = min(coords[coord_index].x,minrap); |
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103 | maxrap = max(coords[coord_index].x,maxrap); |
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104 | |
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105 | Coord2D mirror_point(coords[coord_index]); |
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106 | if (make_mirror(mirror_point, Dlim4mirror)) { |
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107 | coordIDs[jet_i].mirror = ++coord_index; |
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108 | coords[coord_index] = mirror_point; |
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109 | jetIDs[coord_index] = jet_i; |
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110 | } else { |
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111 | coordIDs[jet_i].mirror = Invalid; |
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112 | } |
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113 | } |
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114 | |
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115 | // set them to their actual size... |
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116 | coords.resize(coord_index+1); |
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117 | |
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118 | // establish limits (with some leeway on rapidity) |
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119 | Coord2D left_edge(minrap-1.0, -3.15); // a security margin below -pi |
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120 | Coord2D right_edge(maxrap+1.0, 9.45); // a security margin above 3*pi |
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121 | |
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122 | //cerr << "minrap, maxrap = " << minrap << " " << maxrap << endl; |
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123 | |
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124 | // now create the closest pair search object |
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125 | ClosestPair2D cp(coords, left_edge, right_edge); |
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126 | |
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127 | // cross check to see what's going on... |
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128 | //cerr << "Tree depths before: "; |
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129 | //cp.print_tree_depths(cerr); |
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130 | |
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131 | // and start iterating... |
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132 | vector<Coord2D> new_points(2); |
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133 | vector<unsigned int> cIDs_to_remove(4); |
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134 | vector<unsigned int> new_cIDs(2); |
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135 | |
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136 | do { |
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137 | // find out which pair we recombine |
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138 | unsigned int cID1, cID2; |
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139 | double distance2; |
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140 | cp.closest_pair(cID1,cID2,distance2); |
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141 | |
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142 | // if the closest distance > Dlim, we exit and go to "inclusive" stage |
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143 | if (distance2 > Dlim*Dlim) {break;} |
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144 | |
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145 | // normalise distance as we like it |
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146 | distance2 *= _invR2; |
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147 | |
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148 | // do the recombination... |
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149 | int jet_i = jetIDs[cID1]; |
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150 | int jet_j = jetIDs[cID2]; |
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151 | assert (jet_i != jet_j); // to catch issue of recombining with mirror point |
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152 | int newjet_k; |
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153 | _do_ij_recombination_step(jet_i, jet_j, distance2, newjet_k); |
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154 | |
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155 | // don't bother with any further action if only one active particle |
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156 | // is left (also avoid closest-pair error [cannot remove last particle]). |
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157 | if (--n_active == 1) {break;} |
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158 | |
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159 | // now prepare operations on CP structure |
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160 | cIDs_to_remove.resize(0); |
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161 | cIDs_to_remove.push_back(coordIDs[jet_i].orig); |
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162 | cIDs_to_remove.push_back(coordIDs[jet_j].orig); |
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163 | if (coordIDs[jet_i].mirror != Invalid) |
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164 | cIDs_to_remove.push_back(coordIDs[jet_i].mirror); |
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165 | if (coordIDs[jet_j].mirror != Invalid) |
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166 | cIDs_to_remove.push_back(coordIDs[jet_j].mirror); |
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167 | |
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168 | Coord2D new_point(_jets[newjet_k].rap(),_jets[newjet_k].phi_02pi()); |
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169 | new_points.resize(0); |
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170 | new_points.push_back(new_point); |
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171 | if (make_mirror(new_point, Dlim4mirror)) new_points.push_back(new_point); //< same warning as before concerning the mirroring |
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172 | |
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173 | // carry out actions on search tree |
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174 | cp.replace_many(cIDs_to_remove, new_points, new_cIDs); |
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175 | |
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176 | // now fill in info for new points... |
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177 | coordIDs[newjet_k].orig = new_cIDs[0]; |
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178 | jetIDs[new_cIDs[0]] = newjet_k; |
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179 | if (new_cIDs.size() == 2) { |
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180 | coordIDs[newjet_k].mirror = new_cIDs[1]; |
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181 | jetIDs[new_cIDs[1]] = newjet_k; |
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182 | } else {coordIDs[newjet_k].mirror = Invalid;} |
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183 | |
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184 | //// if we've reached one "active" jet we should exit... |
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185 | //n_active--; |
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186 | //if (n_active == 1) {break;} |
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187 | |
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188 | } while(true); |
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189 | |
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190 | // cross check to see what's going on... |
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191 | //cerr << "Max tree depths after: "; |
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192 | //cp.print_tree_depths(cerr); |
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193 | |
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194 | } |
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195 | |
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196 | |
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197 | //---------------------------------------------------------------------- |
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198 | /// a variant of the closest pair clustering which uses a region of |
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199 | /// size 2pi+2R in phi. |
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200 | void ClusterSequence::_CP2DChan_cluster_2pi2R () { |
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201 | |
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202 | if (_jet_algorithm != cambridge_algorithm) throw Error("CP2DChan clustering method called for a jet-finder that is not the cambridge algorithm"); |
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203 | |
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204 | // run the clustering with mirror copies kept such that only things |
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205 | // within _Rparam of a border are mirrored |
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206 | _CP2DChan_limited_cluster(_Rparam); |
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207 | |
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208 | // |
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209 | _do_Cambridge_inclusive_jets(); |
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210 | } |
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211 | |
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212 | |
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213 | //---------------------------------------------------------------------- |
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214 | /// a variant of the closest pair clustering which uses a region of |
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215 | /// size 2pi + 2*0.3 and then carries on with 2pi+2*R |
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216 | void ClusterSequence::_CP2DChan_cluster_2piMultD () { |
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217 | |
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218 | // do a first run of clustering up to a small distance parameter, |
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219 | if (_Rparam >= 0.39) { |
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220 | _CP2DChan_limited_cluster(min(_Rparam/2,0.3)); |
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221 | } |
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222 | |
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223 | // and then the final round of clustering |
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224 | _CP2DChan_cluster_2pi2R (); |
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225 | } |
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226 | |
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227 | |
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228 | //---------------------------------------------------------------------- |
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229 | /// a 4pi variant of the closest pair clustering |
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230 | void ClusterSequence::_CP2DChan_cluster () { |
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231 | |
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232 | if (_jet_algorithm != cambridge_algorithm) throw Error("_CP2DChan_cluster called for a jet-finder that is not the cambridge algorithm"); |
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233 | |
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234 | unsigned int n = _jets.size(); |
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235 | |
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236 | vector<MirrorInfo> coordIDs(2*n); // link from original to mirror indices |
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237 | vector<int> jetIDs(2*n); // link from mirror to original indices |
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238 | vector<Coord2D> coords(2*n); // our coordinates (and copies) |
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239 | |
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240 | // start things off... |
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241 | double minrap = numeric_limits<double>::max(); |
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242 | double maxrap = -minrap; |
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243 | int coord_index = 0; |
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244 | for (unsigned i = 0; i < n; i++) { |
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245 | // separate out points with infinite rapidity |
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246 | if (_jets[i].E() == abs(_jets[i].pz()) && _jets[i].perp2() == 0.0) { |
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247 | coordIDs[i] = MirrorInfo(BeamJet,BeamJet); |
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248 | } else { |
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249 | coordIDs[i].orig = coord_index; |
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250 | coordIDs[i].mirror = coord_index+1; |
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251 | coords[coord_index] = Coord2D(_jets[i].rap(), _jets[i].phi_02pi()); |
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252 | coords[coord_index+1] = Coord2D(_jets[i].rap(), _jets[i].phi_02pi()+twopi); |
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253 | jetIDs[coord_index] = i; |
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254 | jetIDs[coord_index+1] = i; |
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255 | minrap = min(coords[coord_index].x,minrap); |
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256 | maxrap = max(coords[coord_index].x,maxrap); |
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257 | coord_index += 2; |
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258 | } |
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259 | } |
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260 | // label remaining "mirror info" as saying that there are no jets |
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261 | for (unsigned i = n; i < 2*n; i++) {coordIDs[i].orig = Invalid;} |
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262 | |
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263 | // set them to their actual size... |
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264 | coords.resize(coord_index); |
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265 | |
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266 | // establish limits (with some leeway on rapidity) |
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267 | Coord2D left_edge(minrap-1.0, 0.0); |
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268 | Coord2D right_edge(maxrap+1.0, 2*twopi); |
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269 | |
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270 | // now create the closest pair search object |
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271 | ClosestPair2D cp(coords, left_edge, right_edge); |
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272 | |
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273 | // and start iterating... |
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274 | vector<Coord2D> new_points(2); |
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275 | vector<unsigned int> cIDs_to_remove(4); |
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276 | vector<unsigned int> new_cIDs(2); |
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277 | do { |
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278 | // find out which pair we recombine |
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279 | unsigned int cID1, cID2; |
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280 | double distance2; |
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281 | cp.closest_pair(cID1,cID2,distance2); |
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282 | distance2 *= _invR2; |
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283 | |
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284 | // if the closest distance > 1, we exit and go to "inclusive" stage |
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285 | if (distance2 > 1.0) {break;} |
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286 | |
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287 | // do the recombination... |
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288 | int jet_i = jetIDs[cID1]; |
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289 | int jet_j = jetIDs[cID2]; |
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290 | assert (jet_i != jet_j); // to catch issue of recombining with mirror point |
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291 | int newjet_k; |
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292 | _do_ij_recombination_step(jet_i, jet_j, distance2, newjet_k); |
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293 | |
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294 | // now prepare operations on CP structure |
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295 | cIDs_to_remove[0] = coordIDs[jet_i].orig; |
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296 | cIDs_to_remove[1] = coordIDs[jet_i].mirror; |
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297 | cIDs_to_remove[2] = coordIDs[jet_j].orig; |
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298 | cIDs_to_remove[3] = coordIDs[jet_j].mirror; |
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299 | new_points[0] = Coord2D(_jets[newjet_k].rap(),_jets[newjet_k].phi_02pi()); |
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300 | new_points[1] = Coord2D(_jets[newjet_k].rap(),_jets[newjet_k].phi_02pi()+twopi); |
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301 | // carry out the CP operation |
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302 | //cp.replace_many(cIDs_to_remove, new_points, new_cIDs); |
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303 | // remarkable the following is faster... |
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304 | new_cIDs[0] = cp.replace(cIDs_to_remove[0], cIDs_to_remove[2], new_points[0]); |
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305 | new_cIDs[1] = cp.replace(cIDs_to_remove[1], cIDs_to_remove[3], new_points[1]); |
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306 | // signal that the following jets no longer exist |
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307 | coordIDs[jet_i].orig = Invalid; |
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308 | coordIDs[jet_j].orig = Invalid; |
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309 | // and do bookkeeping for new jet |
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310 | coordIDs[newjet_k] = MirrorInfo(new_cIDs[0], new_cIDs[1]); |
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311 | jetIDs[new_cIDs[0]] = newjet_k; |
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312 | jetIDs[new_cIDs[1]] = newjet_k; |
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313 | |
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314 | // if we've reached one jet we should exit... |
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315 | n--; |
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316 | if (n == 1) {break;} |
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317 | |
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318 | } while(true); |
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319 | |
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320 | |
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321 | // now do "beam" recombinations |
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322 | //for (unsigned int jet_i = 0; jet_i < coordIDs.size(); jet_i++) { |
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323 | // // if we have a predeclared beam jet or a valid set of mirror |
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324 | // // coordinates, recombine then recombine this jet with the beam |
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325 | // if (coordIDs[jet_i].orig == BeamJet || coordIDs[jet_i].orig > 0) { |
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326 | // // diB = 1 _always_ (for the cambridge alg.) |
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327 | // _do_iB_recombination_step(jet_i, 1.0); |
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328 | // } |
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329 | //} |
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330 | |
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331 | _do_Cambridge_inclusive_jets(); |
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332 | |
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333 | //n = _history.size(); |
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334 | //for (unsigned int hist_i = 0; hist_i < n; hist_i++) { |
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335 | // if (_history[hist_i].child == Invalid) { |
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336 | // _do_iB_recombination_step(_history[hist_i].jetp_index, 1.0); |
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337 | // } |
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338 | //} |
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339 | |
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340 | } |
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341 | |
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342 | |
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343 | //---------------------------------------------------------------------- |
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344 | void ClusterSequence::_do_Cambridge_inclusive_jets () { |
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345 | unsigned int n = _history.size(); |
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346 | for (unsigned int hist_i = 0; hist_i < n; hist_i++) { |
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347 | if (_history[hist_i].child == Invalid) { |
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348 | _do_iB_recombination_step(_history[hist_i].jetp_index, 1.0); |
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349 | } |
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350 | } |
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351 | } |
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352 | |
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353 | FASTJET_END_NAMESPACE |
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354 | |
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