FastJet 3.0.2
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00001 //---------------------------------------------------------------------- 00002 /// \file 00003 /// \page Example02 02 - changing the jet definition 00004 /// 00005 /// fastjet basic example program: 00006 /// illustration of the usage of how to change the jet definition 00007 /// used for the clustering (see also fastjet::JetDefinition) 00008 /// 00009 /// run it with : ./02-jetdef < data/single-event.dat 00010 /// 00011 /// Source code: 02-jetdef.cc 00012 //---------------------------------------------------------------------- 00013 // 00014 //STARTHEADER 00015 // $Id: 02-jetdef.cc 2684 2011-11-14 07:41:44Z soyez $ 00016 // 00017 // Copyright (c) 2005-2011, Matteo Cacciari, Gavin P. Salam and Gregory Soyez 00018 // 00019 //---------------------------------------------------------------------- 00020 // This file is part of FastJet. 00021 // 00022 // FastJet is free software; you can redistribute it and/or modify 00023 // it under the terms of the GNU General Public License as published by 00024 // the Free Software Foundation; either version 2 of the License, or 00025 // (at your option) any later version. 00026 // 00027 // The algorithms that underlie FastJet have required considerable 00028 // development and are described in hep-ph/0512210. If you use 00029 // FastJet as part of work towards a scientific publication, please 00030 // include a citation to the FastJet paper. 00031 // 00032 // FastJet is distributed in the hope that it will be useful, 00033 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00034 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00035 // GNU General Public License for more details. 00036 // 00037 // You should have received a copy of the GNU General Public License 00038 // along with FastJet. If not, see <http://www.gnu.org/licenses/>. 00039 //---------------------------------------------------------------------- 00040 //ENDHEADER 00041 00042 00043 #include "fastjet/ClusterSequence.hh" 00044 #include <iostream> // needed for io 00045 #include <cstdio> // needed for io 00046 00047 using namespace std; 00048 00049 /// an example program showing how to use fastjet 00050 int main(){ 00051 00052 // read in input particles 00053 //---------------------------------------------------------- 00054 vector<fastjet::PseudoJet> input_particles; 00055 00056 double px, py , pz, E; 00057 while (cin >> px >> py >> pz >> E) { 00058 // create a fastjet::PseudoJet with these components and put it onto 00059 // back of the input_particles vector 00060 input_particles.push_back(fastjet::PseudoJet(px,py,pz,E)); 00061 } 00062 00063 00064 // create a jet definition: 00065 // a jet algorithm with a given radius parameter 00066 //---------------------------------------------------------- 00067 00068 // select a jet algorithm to use 00069 // 00070 // this could be one of 00071 // {kt_algorithm, cambridge_algorithm, antikt_algorithm, 00072 // genkt_algorithm, ee_kt_algorithm, ee_genkt_algorithm} 00073 // see example 03-plugin.cc for extra options using plugins 00074 // instead of naive algorithms) 00075 fastjet::JetAlgorithm jet_alg = fastjet::kt_algorithm; 00076 00077 // when appropriate select a radius to use 00078 // 00079 // this would not be mandatory for e^+ e^- algorithms (see 05-eplus_eminus.cc) 00080 double R = 0.6; 00081 00082 // select an __optional__ recombination scheme 00083 // 00084 // this could be one of 00085 // {E_scheme, pt_scheme, pt2_scheme, Et_scheme, Et2_scheme, BIpt_scheme, 00086 // BIpt2_scheme, external_sheme} 00087 // 00088 // Notes: 00089 // - for the usage of a user-defined recombination scheme 00090 // (external_scheme), see 11-boosted_higgs.cc 00091 // 00092 // By default, the E_scheme is used 00093 fastjet::RecombinationScheme recomb_scheme=fastjet::E_scheme; 00094 00095 // select an __optional__ strategy 00096 // 00097 // this could be chosen among 00098 // {N2MinHeapTiled, N2Tiled, N2PoorTiled, N2Plain, N3Dumb, 00099 // Best, 00100 // NlnN, NlnN3pi, NlnN4pi, NlnNCam4pi, NlnNCam2pi2R, NlnNCam} 00101 // 00102 // By default, the Best strategy is chosen and we advise to keep 00103 // that default unless you are targeting a very specific usage. Note 00104 // also that the N log (N) strategies for algorithms other than 00105 // Cambridge/Aachen need CGAL support. 00106 fastjet::Strategy strategy = fastjet::Best; 00107 00108 // create the JetDefinition from the above information 00109 fastjet::JetDefinition jet_def(jet_alg, R, recomb_scheme, strategy); 00110 00111 00112 // run the jet clustering with the above jet definition 00113 //---------------------------------------------------------- 00114 fastjet::ClusterSequence clust_seq(input_particles, jet_def); 00115 00116 00117 // get the resulting jets ordered in pt 00118 //---------------------------------------------------------- 00119 double ptmin = 5.0; 00120 vector<fastjet::PseudoJet> inclusive_jets = sorted_by_pt(clust_seq.inclusive_jets(ptmin)); 00121 00122 00123 // tell the user what was done 00124 // - the description of the algorithm used 00125 // - extract the inclusive jets with pt > 5 GeV 00126 // show the output as 00127 // {index, rap, phi, pt} 00128 //---------------------------------------------------------- 00129 cout << "Ran " << jet_def.description() << endl; 00130 00131 // label the columns 00132 printf("%5s %15s %15s %15s\n","jet #", "rapidity", "phi", "pt"); 00133 00134 // print out the details for each jet 00135 for (unsigned int i = 0; i < inclusive_jets.size(); i++) { 00136 printf("%5u %15.8f %15.8f %15.8f\n", 00137 i, inclusive_jets[i].rap(), inclusive_jets[i].phi(), 00138 inclusive_jets[i].perp()); 00139 } 00140 00141 return 0; 00142 }