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//----------------------------------------------------------------------
/// \file
/// \page Example02 02 - changing the jet definition
///
/// fastjet basic example program:
/// illustration of the usage of how to change the jet definition
/// used for the clustering (see also fastjet::JetDefinition)
///
/// run it with : ./02-jetdef < data/single-event.dat
///
/// Source code: 02-jetdef.cc
//----------------------------------------------------------------------
//
//STARTHEADER
// $Id: 02-jetdef.cc 2684 2011-11-14 07:41:44Z soyez $
//
// Copyright (c) 2005-2011, Matteo Cacciari, Gavin P. Salam and Gregory Soyez
//
//----------------------------------------------------------------------
// This file is part of FastJet.
//
// FastJet is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// The algorithms that underlie FastJet have required considerable
// development and are described in hep-ph/0512210. If you use
// FastJet as part of work towards a scientific publication, please
// include a citation to the FastJet paper.
//
// FastJet is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with FastJet. If not, see <http://www.gnu.org/licenses/>.
//----------------------------------------------------------------------
//ENDHEADER
#include "fastjet/ClusterSequence.hh"
#include <iostream> // needed for io
#include <cstdio> // needed for io
using namespace std;
/// an example program showing how to use fastjet
int main(){
// read in input particles
//----------------------------------------------------------
vector<fastjet::PseudoJet> input_particles;
double px, py , pz, E;
while (cin >> px >> py >> pz >> E) {
// create a fastjet::PseudoJet with these components and put it onto
// back of the input_particles vector
input_particles.push_back(fastjet::PseudoJet(px,py,pz,E));
}
// create a jet definition:
// a jet algorithm with a given radius parameter
//----------------------------------------------------------
// select a jet algorithm to use
//
// this could be one of
// {kt_algorithm, cambridge_algorithm, antikt_algorithm,
// genkt_algorithm, ee_kt_algorithm, ee_genkt_algorithm}
// see example 03-plugin.cc for extra options using plugins
// instead of naive algorithms)
fastjet::JetAlgorithm jet_alg = fastjet::kt_algorithm;
// when appropriate select a radius to use
//
// this would not be mandatory for e^+ e^- algorithms (see 05-eplus_eminus.cc)
double R = 0.6;
// select an __optional__ recombination scheme
//
// this could be one of
// {E_scheme, pt_scheme, pt2_scheme, Et_scheme, Et2_scheme, BIpt_scheme,
// BIpt2_scheme, external_sheme}
//
// Notes:
// - for the usage of a user-defined recombination scheme
// (external_scheme), see 11-boosted_higgs.cc
//
// By default, the E_scheme is used
fastjet::RecombinationScheme recomb_scheme=fastjet::E_scheme;
// select an __optional__ strategy
//
// this could be chosen among
// {N2MinHeapTiled, N2Tiled, N2PoorTiled, N2Plain, N3Dumb,
// Best,
// NlnN, NlnN3pi, NlnN4pi, NlnNCam4pi, NlnNCam2pi2R, NlnNCam}
//
// By default, the Best strategy is chosen and we advise to keep
// that default unless you are targeting a very specific usage. Note
// also that the N log (N) strategies for algorithms other than
// Cambridge/Aachen need CGAL support.
fastjet::Strategy strategy = fastjet::Best;
// create the JetDefinition from the above information
fastjet::JetDefinition jet_def(jet_alg, R, recomb_scheme, strategy);
// run the jet clustering with the above jet definition
//----------------------------------------------------------
fastjet::ClusterSequence clust_seq(input_particles, jet_def);
// get the resulting jets ordered in pt
//----------------------------------------------------------
double ptmin = 5.0;
vector<fastjet::PseudoJet> inclusive_jets = sorted_by_pt(clust_seq.inclusive_jets(ptmin));
// tell the user what was done
// - the description of the algorithm used
// - extract the inclusive jets with pt > 5 GeV
// show the output as
// {index, rap, phi, pt}
//----------------------------------------------------------
cout << "Ran " << jet_def.description() << endl;
// label the columns
printf("%5s %15s %15s %15s\n","jet #", "rapidity", "phi", "pt");
// print out the details for each jet
for (unsigned int i = 0; i < inclusive_jets.size(); i++) {
printf("%5u %15.8f %15.8f %15.8f\n",
i, inclusive_jets[i].rap(), inclusive_jets[i].phi(),
inclusive_jets[i].perp());
}
return 0;
}
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