| 1 | //FJSTARTHEADER
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| 2 | // $Id: ClusterSequence_CP2DChan.cc 4442 2020-05-05 07:50:11Z soyez $
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| 3 | //
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| 4 | // Copyright (c) 2005-2020, 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. They are described in the original FastJet paper,
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| 16 | // hep-ph/0512210 and in the manual, arXiv:1111.6097. If you use
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| 17 | // FastJet as part of work towards a scientific publication, please
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| 18 | // quote the version you use and include a citation to the manual and
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| 19 | // optionally also to hep-ph/0512210.
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| 20 | //
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| 21 | // FastJet is distributed in the hope that it will be useful,
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| 22 | // but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 23 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 24 | // GNU General Public License for more details.
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| 25 | //
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| 26 | // You should have received a copy of the GNU General Public License
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| 27 | // along with FastJet. If not, see <http://www.gnu.org/licenses/>.
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| 28 | //----------------------------------------------------------------------
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| 29 | //FJENDHEADER
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| 30 |
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| 31 | #include "fastjet/ClusterSequence.hh"
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| 32 | #include "fastjet/internal/ClosestPair2D.hh"
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| 33 | #include<limits>
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| 34 | #include<vector>
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| 35 | #include<cmath>
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| 36 | #include<iostream>
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| 37 |
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| 38 | FASTJET_BEGIN_NAMESPACE // defined in fastjet/internal/base.hh
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| 39 |
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| 40 | using namespace std;
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| 41 |
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| 42 | // place for things we don't want outside world to run into
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| 43 | namespace Private {
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| 44 | /// class for helping us deal with mirror-image particles.
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| 45 | class MirrorInfo{
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| 46 | public:
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| 47 | int orig, mirror;
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| 48 | MirrorInfo(int a, int b) : orig(a), mirror(b) {}
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| 49 | MirrorInfo() : orig(0), mirror(0) {} // set dummy values to keep static code checkers happy
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| 50 | };
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| 51 |
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| 52 | /// if there is a need for a mirror when looking for closest pairs
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| 53 | /// up to distance D, then return true and turn the supplied point
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| 54 | /// into its mirror copy
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| 55 | bool make_mirror(Coord2D & point, double Dlim) {
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| 56 | if (point.y < Dlim) {point.y += twopi; return true;}
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| 57 | if (twopi-point.y < Dlim) {point.y -= twopi; return true;}
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| 58 | return false;
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| 59 | }
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| 60 |
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| 61 | }
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| 62 |
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| 63 | using namespace Private;
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| 64 |
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| 65 |
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| 66 | //----------------------------------------------------------------------
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| 67 | /// clusters only up to a distance Dlim -- does not deal with "inclusive" jets
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| 68 | /// -- these are left to some other part of the program
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| 69 | void ClusterSequence::_CP2DChan_limited_cluster (double Dlim) {
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| 70 |
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| 71 | unsigned int n = _initial_n;
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| 72 |
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| 73 | vector<MirrorInfo> coordIDs(2*n); // coord IDs of a given jetID
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| 74 | vector<int> jetIDs(2*n); // jet ID for a given coord ID
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| 75 | vector<Coord2D> coords(2*n); // our coordinates (and copies)
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| 76 |
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| 77 | // particles within a distance Dlim of the phi edges (phi<Dlim ||
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| 78 | // phi>2pi-Dli;) will be mirrored. For Dlim>pi, this could lead to
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| 79 | // particles copies outside the fixed range in phi which is
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| 80 | // [-pi:3pi] (see make_mirror above). Since in that case all
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| 81 | // particles get copied anywaym we can just copy particles up to a
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| 82 | // distance "pi" from the edges
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| 83 | double Dlim4mirror = min(Dlim,pi);
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| 84 |
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| 85 | // start things off...
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| 86 | double minrap = numeric_limits<double>::max();
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| 87 | double maxrap = -minrap;
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| 88 | int coord_index = -1;
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| 89 | int n_active = 0;
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| 90 | for (unsigned jet_i = 0; jet_i < _jets.size(); jet_i++) {
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| 91 |
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| 92 | // skip jets that already have children or that have infinite
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| 93 | // rapidity
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| 94 | if (_history[_jets[jet_i].cluster_hist_index()].child != Invalid ||
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| 95 | (_jets[jet_i].E() == abs(_jets[jet_i].pz()) &&
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| 96 | _jets[jet_i].perp2() == 0.0)
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| 97 | ) {continue;}
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| 98 |
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| 99 | n_active++;
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| 100 |
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| 101 | coordIDs[jet_i].orig = ++coord_index;
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| 102 | coords[coord_index] = Coord2D(_jets[jet_i].rap(), _jets[jet_i].phi_02pi());
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| 103 | jetIDs[coord_index] = jet_i;
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| 104 | minrap = min(coords[coord_index].x,minrap);
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| 105 | maxrap = max(coords[coord_index].x,maxrap);
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| 106 |
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| 107 | Coord2D mirror_point(coords[coord_index]);
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| 108 | if (make_mirror(mirror_point, Dlim4mirror)) {
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| 109 | coordIDs[jet_i].mirror = ++coord_index;
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| 110 | coords[coord_index] = mirror_point;
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| 111 | jetIDs[coord_index] = jet_i;
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| 112 | } else {
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| 113 | coordIDs[jet_i].mirror = Invalid;
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| 114 | }
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| 115 | }
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| 116 |
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| 117 | // set them to their actual size...
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| 118 | coords.resize(coord_index+1);
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| 119 |
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| 120 | // establish limits (with some leeway on rapidity)
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| 121 | Coord2D left_edge(minrap-1.0, -3.15); // a security margin below -pi
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| 122 | Coord2D right_edge(maxrap+1.0, 9.45); // a security margin above 3*pi
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| 123 |
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| 124 | //cerr << "minrap, maxrap = " << minrap << " " << maxrap << endl;
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| 125 |
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| 126 | // now create the closest pair search object
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| 127 | ClosestPair2D cp(coords, left_edge, right_edge);
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| 128 |
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| 129 | // cross check to see what's going on...
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| 130 | //cerr << "Tree depths before: ";
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| 131 | //cp.print_tree_depths(cerr);
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| 132 |
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| 133 | // and start iterating...
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| 134 | vector<Coord2D> new_points(2);
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| 135 | vector<unsigned int> cIDs_to_remove(4);
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| 136 | vector<unsigned int> new_cIDs(2);
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| 137 |
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| 138 | do {
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| 139 | // find out which pair we recombine
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| 140 | unsigned int cID1, cID2;
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| 141 | double distance2;
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| 142 | cp.closest_pair(cID1,cID2,distance2);
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| 143 |
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| 144 | // if the closest distance > Dlim, we exit and go to "inclusive" stage
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| 145 | if (distance2 > Dlim*Dlim) {break;}
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| 146 |
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| 147 | // normalise distance as we like it
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| 148 | distance2 *= _invR2;
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| 149 |
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| 150 | // do the recombination...
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| 151 | int jet_i = jetIDs[cID1];
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| 152 | int jet_j = jetIDs[cID2];
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| 153 | assert (jet_i != jet_j); // to catch issue of recombining with mirror point
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| 154 | int newjet_k;
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| 155 | _do_ij_recombination_step(jet_i, jet_j, distance2, newjet_k);
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| 156 |
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| 157 | // don't bother with any further action if only one active particle
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| 158 | // is left (also avoid closest-pair error [cannot remove last particle]).
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| 159 | if (--n_active == 1) {break;}
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| 160 |
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| 161 | // now prepare operations on CP structure
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| 162 | cIDs_to_remove.resize(0);
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| 163 | cIDs_to_remove.push_back(coordIDs[jet_i].orig);
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| 164 | cIDs_to_remove.push_back(coordIDs[jet_j].orig);
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| 165 | if (coordIDs[jet_i].mirror != Invalid)
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| 166 | cIDs_to_remove.push_back(coordIDs[jet_i].mirror);
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| 167 | if (coordIDs[jet_j].mirror != Invalid)
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| 168 | cIDs_to_remove.push_back(coordIDs[jet_j].mirror);
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| 169 |
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| 170 | Coord2D new_point(_jets[newjet_k].rap(),_jets[newjet_k].phi_02pi());
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| 171 | new_points.resize(0);
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| 172 | new_points.push_back(new_point);
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| 173 | if (make_mirror(new_point, Dlim4mirror)) new_points.push_back(new_point); //< same warning as before concerning the mirroring
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| 174 |
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| 175 | // carry out actions on search tree
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| 176 | cp.replace_many(cIDs_to_remove, new_points, new_cIDs);
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| 177 |
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| 178 | // now fill in info for new points...
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| 179 | coordIDs[newjet_k].orig = new_cIDs[0];
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| 180 | jetIDs[new_cIDs[0]] = newjet_k;
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| 181 | if (new_cIDs.size() == 2) {
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| 182 | coordIDs[newjet_k].mirror = new_cIDs[1];
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| 183 | jetIDs[new_cIDs[1]] = newjet_k;
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| 184 | } else {coordIDs[newjet_k].mirror = Invalid;}
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| 185 |
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| 186 | //// if we've reached one "active" jet we should exit...
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| 187 | //n_active--;
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| 188 | //if (n_active == 1) {break;}
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| 189 |
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| 190 | } while(true);
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| 191 |
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| 192 | // cross check to see what's going on...
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| 193 | //cerr << "Max tree depths after: ";
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| 194 | //cp.print_tree_depths(cerr);
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| 195 |
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| 196 | }
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| 197 |
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| 198 |
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| 199 | //----------------------------------------------------------------------
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| 200 | /// a variant of the closest pair clustering which uses a region of
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| 201 | /// size 2pi+2R in phi.
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| 202 | void ClusterSequence::_CP2DChan_cluster_2pi2R () {
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| 203 |
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| 204 | 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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| 205 |
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| 206 | // run the clustering with mirror copies kept such that only things
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| 207 | // within _Rparam of a border are mirrored
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| 208 | _CP2DChan_limited_cluster(_Rparam);
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| 209 |
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| 210 | //
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| 211 | _do_Cambridge_inclusive_jets();
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| 212 | }
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| 213 |
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| 214 |
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| 215 | //----------------------------------------------------------------------
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| 216 | /// a variant of the closest pair clustering which uses a region of
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| 217 | /// size 2pi + 2*0.3 and then carries on with 2pi+2*R
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| 218 | void ClusterSequence::_CP2DChan_cluster_2piMultD () {
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| 219 |
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| 220 | // do a first run of clustering up to a small distance parameter,
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| 221 | if (_Rparam >= 0.39) {
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| 222 | _CP2DChan_limited_cluster(min(_Rparam/2,0.3));
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| 223 | }
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| 224 |
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| 225 | // and then the final round of clustering
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| 226 | _CP2DChan_cluster_2pi2R ();
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| 227 | }
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| 228 |
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| 229 |
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| 230 | //----------------------------------------------------------------------
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| 231 | /// a 4pi variant of the closest pair clustering
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| 232 | void ClusterSequence::_CP2DChan_cluster () {
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| 233 |
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| 234 | if (_jet_algorithm != cambridge_algorithm) throw Error("_CP2DChan_cluster called for a jet-finder that is not the cambridge algorithm");
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| 235 |
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| 236 | unsigned int n = _jets.size();
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| 237 |
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| 238 | vector<MirrorInfo> coordIDs(2*n); // link from original to mirror indices
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| 239 | vector<int> jetIDs(2*n); // link from mirror to original indices
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| 240 | vector<Coord2D> coords(2*n); // our coordinates (and copies)
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| 241 |
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| 242 | // start things off...
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| 243 | double minrap = numeric_limits<double>::max();
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| 244 | double maxrap = -minrap;
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| 245 | int coord_index = 0;
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| 246 | for (unsigned i = 0; i < n; i++) {
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| 247 | // separate out points with infinite rapidity
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| 248 | if (_jets[i].E() == abs(_jets[i].pz()) && _jets[i].perp2() == 0.0) {
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| 249 | coordIDs[i] = MirrorInfo(BeamJet,BeamJet);
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| 250 | } else {
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| 251 | coordIDs[i].orig = coord_index;
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| 252 | coordIDs[i].mirror = coord_index+1;
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| 253 | coords[coord_index] = Coord2D(_jets[i].rap(), _jets[i].phi_02pi());
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| 254 | coords[coord_index+1] = Coord2D(_jets[i].rap(), _jets[i].phi_02pi()+twopi);
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| 255 | jetIDs[coord_index] = i;
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| 256 | jetIDs[coord_index+1] = i;
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| 257 | minrap = min(coords[coord_index].x,minrap);
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| 258 | maxrap = max(coords[coord_index].x,maxrap);
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| 259 | coord_index += 2;
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| 260 | }
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| 261 | }
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| 262 | // label remaining "mirror info" as saying that there are no jets
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| 263 | for (unsigned i = n; i < 2*n; i++) {coordIDs[i].orig = Invalid;}
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| 264 |
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| 265 | // set them to their actual size...
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| 266 | coords.resize(coord_index);
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| 267 |
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| 268 | // establish limits (with some leeway on rapidity)
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| 269 | Coord2D left_edge(minrap-1.0, 0.0);
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| 270 | Coord2D right_edge(maxrap+1.0, 2*twopi);
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| 271 |
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| 272 | // now create the closest pair search object
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| 273 | ClosestPair2D cp(coords, left_edge, right_edge);
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| 274 |
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| 275 | // and start iterating...
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| 276 | vector<Coord2D> new_points(2);
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| 277 | vector<unsigned int> cIDs_to_remove(4);
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| 278 | vector<unsigned int> new_cIDs(2);
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| 279 | do {
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| 280 | // find out which pair we recombine
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| 281 | unsigned int cID1, cID2;
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| 282 | double distance2;
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| 283 | cp.closest_pair(cID1,cID2,distance2);
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| 284 | distance2 *= _invR2;
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| 285 |
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| 286 | // if the closest distance > 1, we exit and go to "inclusive" stage
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| 287 | if (distance2 > 1.0) {break;}
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| 288 |
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| 289 | // do the recombination...
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| 290 | int jet_i = jetIDs[cID1];
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| 291 | int jet_j = jetIDs[cID2];
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| 292 | assert (jet_i != jet_j); // to catch issue of recombining with mirror point
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| 293 | int newjet_k;
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| 294 | _do_ij_recombination_step(jet_i, jet_j, distance2, newjet_k);
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| 295 |
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| 296 | // now prepare operations on CP structure
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| 297 | cIDs_to_remove[0] = coordIDs[jet_i].orig;
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| 298 | cIDs_to_remove[1] = coordIDs[jet_i].mirror;
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| 299 | cIDs_to_remove[2] = coordIDs[jet_j].orig;
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| 300 | cIDs_to_remove[3] = coordIDs[jet_j].mirror;
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| 301 | new_points[0] = Coord2D(_jets[newjet_k].rap(),_jets[newjet_k].phi_02pi());
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| 302 | new_points[1] = Coord2D(_jets[newjet_k].rap(),_jets[newjet_k].phi_02pi()+twopi);
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| 303 | // carry out the CP operation
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| 304 | //cp.replace_many(cIDs_to_remove, new_points, new_cIDs);
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| 305 | // remarkable the following is faster...
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| 306 | new_cIDs[0] = cp.replace(cIDs_to_remove[0], cIDs_to_remove[2], new_points[0]);
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| 307 | new_cIDs[1] = cp.replace(cIDs_to_remove[1], cIDs_to_remove[3], new_points[1]);
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| 308 | // signal that the following jets no longer exist
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| 309 | coordIDs[jet_i].orig = Invalid;
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| 310 | coordIDs[jet_j].orig = Invalid;
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| 311 | // and do bookkeeping for new jet
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| 312 | coordIDs[newjet_k] = MirrorInfo(new_cIDs[0], new_cIDs[1]);
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| 313 | jetIDs[new_cIDs[0]] = newjet_k;
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| 314 | jetIDs[new_cIDs[1]] = newjet_k;
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| 315 |
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| 316 | // if we've reached one jet we should exit...
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| 317 | n--;
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| 318 | if (n == 1) {break;}
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| 319 |
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| 320 | } while(true);
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| 321 |
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| 322 |
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| 323 | // now do "beam" recombinations
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| 324 | //for (unsigned int jet_i = 0; jet_i < coordIDs.size(); jet_i++) {
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| 325 | // // if we have a predeclared beam jet or a valid set of mirror
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| 326 | // // coordinates, recombine then recombine this jet with the beam
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| 327 | // if (coordIDs[jet_i].orig == BeamJet || coordIDs[jet_i].orig > 0) {
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| 328 | // // diB = 1 _always_ (for the cambridge alg.)
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| 329 | // _do_iB_recombination_step(jet_i, 1.0);
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| 330 | // }
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| 331 | //}
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| 332 |
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| 333 | _do_Cambridge_inclusive_jets();
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| 334 |
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| 335 | //n = _history.size();
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| 336 | //for (unsigned int hist_i = 0; hist_i < n; hist_i++) {
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| 337 | // if (_history[hist_i].child == Invalid) {
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| 338 | // _do_iB_recombination_step(_history[hist_i].jetp_index, 1.0);
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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 |
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| 345 | //----------------------------------------------------------------------
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| 346 | void ClusterSequence::_do_Cambridge_inclusive_jets () {
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| 347 | unsigned int n = _history.size();
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| 348 | for (unsigned int hist_i = 0; hist_i < n; hist_i++) {
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| 349 | if (_history[hist_i].child == Invalid) {
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| 350 | _do_iB_recombination_step(_history[hist_i].jetp_index, 1.0);
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| 351 | }
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| 352 | }
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| 353 | }
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| 354 |
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| 355 | FASTJET_END_NAMESPACE
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| 356 |
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