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ktjet_example.cc
//----------------------------------------------------------------------
// ktjet example program that should do the same thing as the
// fastjet_example program (as of 3 Feb 2006)
//
// NB: the ../Makefile may need to be modified to set proper
// paths for access to the CLHEP and KtJet libraries.
//----------------------------------------------------------------------
#include<iostream> // needed for io
#include<sstream> // needed for internal io
#include<vector>
/** Need to include these KtJet Headers */
#include "KtJet/KtEvent.h"
#include "KtJet/KtLorentzVector.h"
using namespace std;
using namespace KtJet;
// a declaration of a function that pretty prints a list of jets
void print_jets (const vector<KtLorentzVector> &);
/// an example program showing how the fastjet_example program would
/// be translated for use with ktjet.
int main (int argc, char ** argv) {
vector<KtLorentzVector> input_particles;
// read in input particles
double px, py , pz, E;
while (cin >> px >> py >> pz >> E) {
// create a KtLorentzVector with these components and put it onto
// back of the input_particles vector
input_particles.push_back(KtLorentzVector(px,py,pz,E));
}
// run the inclusive jet clustering in PP mode using the covariant
// E-scheme for recobination (type=4, angle=2, recom=1, rparameter=1.0)
double Rparam = 1.0;
KtEvent clust_seq(input_particles,4,2,1,Rparam);
// extract the inclusive jets with pt > 5 GeV, sorted by pt
double ptmin = 5.0;
vector<KtLorentzVector> temporary_jets = clust_seq.getJetsPt();
vector<KtLorentzVector> inclusive_jets;
for (unsigned int i = 0; i < temporary_jets.size(); i++) {
if (temporary_jets[i].perp() >= ptmin) {
inclusive_jets.push_back(temporary_jets[i]);}
else {break;}
}
// print them out
cout << "Printing inclusive jets with pt > "<< ptmin<<" GeV\n";
cout << "---------------------------------------\n";
print_jets(inclusive_jets);
cout << endl;
// Extract the exclusive jets with dcut = 25 GeV^2.
double dcut = 25.0;
// Note that KtJet's definition of dij differs from Ellis&Soper (and
// fastjet) in the case where Rparam /= 1.0 (though in this case one
// should perhaps not be using the exclusive kt algorithm in any case).
clust_seq.findJetsD(dcut * Rparam*Rparam);
vector<KtLorentzVector> exclusive_jets = clust_seq.getJetsPt();
// print them out
cout << "Printing exclusive jets with dcut = "<< dcut<<" GeV^2\n";
cout << "--------------------------------------------\n";
print_jets(exclusive_jets);
}
//----------------------------------------------------------------------
// a function that pretty prints a list of jets
void print_jets (const vector<KtLorentzVector> & jets) {
// label the columns
printf("%5s %15s %15s %15s %15s\n","jet #", "rapidity",
"phi", "pt", "n constituents");
// print out the details for each jet
for (unsigned int i = 0; i < jets.size(); i++) {
int n_constituents = jets[i].getConstituents().size();
double phi = jets[i].phi();
if (phi < 0.0) {phi += 6.283185307179586476925286766559005768394;}
printf("%5u %15.8f %15.8f %15.8f %8u\n",
i, jets[i].rapidity(), phi,
jets[i].perp(), n_constituents);
}
}
main
int main()
an example program showing how to use fastjet
Definition 01-basic.cc:50