main44
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// main44.cc is a part of the PYTHIA event generator.
// Copyright (C) 2021 Torbjorn Sjostrand.
// PYTHIA is licenced under the GNU GPL v2 or later, see COPYING for details.
// Please respect the MCnet Guidelines, see GUIDELINES for details.
// Author: Stefan Prestel .
// Keywords:
// LHE file
// Hepmc
// This program (main44.cc) illustrates how a file with HepMC2 events can be
// generated by Pythia8. See main45.cc for how to ouput HepMC3 events instead.
// Note: both main44.cc and main45.cc can use the same main44.cmnd input card.
#include "Pythia8/Pythia.h"
#ifndef HEPMC2
#include "Pythia8Plugins/HepMC3.h"
#else
#include "Pythia8Plugins/HepMC2.h"
#endif
#include
using namespace Pythia8;
//==========================================================================
// Example main programm to illustrate merging.
int main( int argc, char* argv[] ){
// Check that correct number of command-line arguments
if (argc != 3) {
cerr << " Unexpected number of command-line arguments ("< nAbort) {doAbort = true; break;}
else continue;
}
// Get event weight(s).
double evtweight = pythia.info.weight();
// Do not print zero-weight events.
if ( evtweight == 0. ) continue;
// Work with weighted (LHA strategy=-4) events.
double normhepmc = 1.;
if (abs(pythia.info.lhaStrategy()) == 4)
normhepmc = 1. / double(1e9*nEvent);
// Work with unweighted events.
else
normhepmc = xs / double(1e9*nEvent);
// Set event weight
//hepmcevt.weights().push_back(evtweight*normhepmc);
// Fill HepMC event
ToHepMC.fillNextEvent( pythia );
// Add the weight of the current event to the cross section.
sigmaTotal += evtweight*normhepmc;
sigmaSample += evtweight*normhepmc;
errorTotal += pow2(evtweight*normhepmc);
errorSample += pow2(evtweight*normhepmc);
// Report cross section to hepmc
ToHepMC.setXSec( sigmaTotal*1e9, pythia.info.sigmaErr()*1e9 );
// Write the HepMC event to file. Done with it.
ToHepMC.writeEvent();
} // end loop over events to generate.
if (doAbort) break;
// print cross section, errors
pythia.stat();
cout << endl << " Contribution of sample " << iRuns
<< " to the inclusive cross section : "
<< scientific << setprecision(8)
<< sigmaSample << " +- " << sqrt(errorSample) << endl;
}
cout << endl << endl << endl;
if (doAbort)
cout << " Run was not completed owing to too many aborted events" << endl;
cout << endl << endl << endl;
// Done
return 0;
}