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//////////////////////////////////////////////////////////////////////////
// Matt.Dobbs@Cern.CH, December 1999
// November 2000, updated to use Pythia 6.1
// example of generating events with Pythia
// using HepMC/PythiaWrapper.h
// Events are read into the HepMC event record from the FORTRAN HEPEVT
// common block using the IO_HEPEVT strategy -- nothing is done with them.
// This program is just used to find the total time required to transfer
// from HEPEVT into the HepMC event record.
//////////////////////////////////////////////////////////////////////////
// To Compile: go to the HepMC directory and type:
// gmake examples/example_MyPythiaOnlyTo HepMC.exe
//
// See comments in examples/example_MyPythia.cxx regarding the HEPEVT wrapper.
//
#include <iostream>
#include "HepMC/PythiaWrapper.h"
#include "HepMC/IO_HEPEVT.h"
#include "HepMC/GenEvent.h"
#include "PythiaHelper.h"
int main() {
//
//........................................HEPEVT
// Pythia 6.1 uses HEPEVT with 4000 entries and 8-byte floating point
// numbers. We need to explicitly pass this information to the
// HEPEVT_Wrapper.
//
HepMC::HEPEVT_Wrapper::set_max_number_entries(4000);
HepMC::HEPEVT_Wrapper::set_sizeof_real(8);
//
//........................................PYTHIA INITIALIZATIONS
initPythia();
//
//........................................HepMC INITIALIZATIONS
//
// Instantiate an IO strategy for reading from HEPEVT.
HepMC::IO_HEPEVT hepevtio;
//
//........................................EVENT LOOP
for ( int i = 1; i <= 100; i++ ) {
if ( i%50==1 ) std::cout << "Processing Event Number "
<< i << std::endl;
call_pyevnt(); // generate one event with Pythia
// pythia pyhepc routine convert common PYJETS in common HEPEVT
call_pyhepc( 1 );
HepMC::GenEvent* evt = hepevtio.read_next_event();
// define the units (Pythia uses GeV and mm)
evt->use_units(HepMC::Units::GEV, HepMC::Units::MM);
// set number of multi parton interactions
evt->set_mpi( pypars.msti[31-1] );
// set cross section information
evt->set_cross_section( HepMC::getPythiaCrossSection() );
//
//.......................USER WOULD PROCESS EVENT HERE
//
// we also need to delete the created event from memory
delete evt;
}
//........................................TERMINATION
// write out some information from Pythia to the screen
call_pystat( 1 );
return 0;
}
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