ClusterSequence_DumbN3.cc

Go to the documentation of this file.
00001 //STARTHEADER
00002 // $Id: ClusterSequence_DumbN3.cc 293 2006-08-17 19:38:38Z salam $
00003 //
00004 // Copyright (c) 2005-2006, Matteo Cacciari and Gavin Salam
00005 //
00006 //----------------------------------------------------------------------
00007 // This file is part of FastJet.
00008 //
00009 //  FastJet is free software; you can redistribute it and/or modify
00010 //  it under the terms of the GNU General Public License as published by
00011 //  the Free Software Foundation; either version 2 of the License, or
00012 //  (at your option) any later version.
00013 //
00014 //  The algorithms that underlie FastJet have required considerable
00015 //  development and are described in hep-ph/0512210. If you use
00016 //  FastJet as part of work towards a scientific publication, please
00017 //  include a citation to the FastJet paper.
00018 //
00019 //  FastJet is distributed in the hope that it will be useful,
00020 //  but WITHOUT ANY WARRANTY; without even the implied warranty of
00021 //  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00022 //  GNU General Public License for more details.
00023 //
00024 //  You should have received a copy of the GNU General Public License
00025 //  along with FastJet; if not, write to the Free Software
00026 //  Foundation, Inc.:
00027 //      59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
00028 //----------------------------------------------------------------------
00029 //ENDHEADER
00030 
00031 
00032 #include "fastjet/PseudoJet.hh"
00033 #include "fastjet/ClusterSequence.hh"
00034 #include<iostream>
00035 #include<cmath>
00036 #include <cstdlib>
00037 #include<cassert>
00038 
00039 FASTJET_BEGIN_NAMESPACE      // defined in fastjet/internal/base.hh
00040 
00041 
00042 using namespace std;
00043 
00044 
00045 //----------------------------------------------------------------------
00050 void ClusterSequence::_really_dumb_cluster () {
00051 
00052   // the array that will be overwritten here will be one
00053   // of pointers to jets.
00054   vector<PseudoJet *> jetsp(_jets.size());
00055   vector<int>         indices(_jets.size());
00056 
00057   for (size_t i = 0; i<_jets.size(); i++) {
00058     jetsp[i] = & _jets[i];
00059     indices[i] = i;
00060   }
00061 
00062   for (int n = jetsp.size(); n > 0; n--) {
00063     int ii, jj;
00064     // find smallest beam distance [remember jet_scale_for_algorithm 
00065     // will return kt^2 for the kt-algorithm and 1 for the Cambridge/Aachen]
00066     double ymin = jet_scale_for_algorithm(*(jetsp[0]));
00067     ii = 0; jj = -2;
00068     for (int i = 0; i < n; i++) {
00069       double yiB = jet_scale_for_algorithm(*(jetsp[i]));
00070       if (yiB < ymin) {
00071         ymin = yiB; ii = i; jj = -2;}
00072     }
00073 
00074     // find smallest distance between pair of jetsp
00075     for (int i = 0; i < n-1; i++) {
00076       for (int j = i+1; j < n; j++) {
00077         //double y = jetsp[i]->kt_distance(*jetsp[j])*_invR2;
00078         double y = min(jet_scale_for_algorithm(*(jetsp[i])), 
00079                        jet_scale_for_algorithm(*(jetsp[j])))
00080                     * jetsp[i]->plain_distance(*jetsp[j])*_invR2;
00081         if (y < ymin) {ymin = y; ii = i; jj = j;}
00082       }
00083     }
00084 
00085     // output recombination sequence
00086     // old "ktclus" way of labelling
00087     //cout <<n<< " "<< ii+1 << " with " << jj+1 << "; y = "<< ymin<<endl;
00088     // new delaunay way of labelling
00089     int jjindex_or_beam, iiindex;
00090     if (jj < 0) {jjindex_or_beam = BeamJet; iiindex = indices[ii];} 
00091     else {
00092       jjindex_or_beam = max(indices[ii],indices[jj]);
00093       iiindex =         min(indices[ii],indices[jj]);
00094     }
00095 
00096     // now recombine
00097     int newn = 2*jetsp.size() - n;
00098     if (jj >= 0) {
00099       // combine pair
00100       int nn; // new jet index
00101       _do_ij_recombination_step(jetsp[ii]-&_jets[0], 
00102                                 jetsp[jj]-&_jets[0], ymin, nn);
00103       
00104       // sort out internal bookkeeping
00105       jetsp[ii] = &_jets[nn];
00106       // have jj point to jet that was pointed at by n-1 
00107       // (since original jj is no longer current, so put n-1 into jj)
00108       jetsp[jj] = jetsp[n-1];
00109       indices[ii] = newn;
00110       indices[jj] = indices[n-1];
00111 
00112       //OBS_jets.push_back(*jetsp[ii] + *jetsp[jj]);
00113       //OBSjetsp[ii] = &_jets[_jets.size()-1];
00114       //OBS// have jj point to jet that was pointed at by n-1 
00115       //OBS// (since original jj is no longer current, so put n-1 into jj)
00116       //OBSjetsp[jj] = jetsp[n-1];
00117       //OBS
00118       //OBSindices[ii] = newn;
00119       //OBSindices[jj] = indices[n-1];
00120       //OBS_add_step_to_history(newn,iiindex,
00121       //OBS                           jjindex_or_beam,_jets.size()-1,ymin);
00122     } else {
00123       // combine ii with beam
00124       _do_iB_recombination_step(jetsp[ii]-&_jets[0], ymin);
00125       // put last jet (pointer) in place of ii (which has disappeared)
00126       jetsp[ii] = jetsp[n-1];
00127       indices[ii] = indices[n-1];
00128       //OBS_add_step_to_history(newn,iiindex,jjindex_or_beam,Invalid, ymin);
00129     }
00130   }
00131 
00132 }
00133 
00134 FASTJET_END_NAMESPACE
00135 

Generated on Tue Dec 18 17:05:03 2007 for fastjet by  doxygen 1.5.2