PFClusterWidthCalculator.cxx

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#include "eflowRec/PFClusterWidthCalculator.h"
 
#include "eflowRec/eflowUtil.h"
 
#include <cmath>
 
PFClusterWidthCalculator::PFClusterWidthCalculator() : m_etaPhiLowerLimit(0.0025),m_etaMean(0.0),m_phiMean(0.0) {}
 
 
 
std::pair<double,double> PFClusterWidthCalculator::getPFClusterCoordinateWidth(const std::vector<double>& eta, const std::vector<double>& phi, const double& clusterEta, const double& clusterPhi, unsigned int nCells){
 
    if (nCells <= 1) {
        m_etaMean = clusterEta;
        m_phiMean = clusterPhi;
        return std::make_pair(m_etaPhiLowerLimit,m_etaPhiLowerLimit);
    }
 
    double etaSum(0.0);
    double etaSum2(0.0);
    double phiSum(0.0);
    double phiSum2(0.0);
 
    for(unsigned int iCell=0; iCell<nCells; ++iCell){
        etaSum += eta[iCell];
        etaSum2 += eta[iCell]*eta[iCell];
        double thisCellPhi = eflowAzimuth(phi[iCell]).cycle(clusterPhi);
        phiSum += thisCellPhi;
        phiSum2 += thisCellPhi*thisCellPhi;
 
    }
 
    m_etaMean = etaSum/static_cast<double>(nCells);
    m_phiMean = phiSum/static_cast<double>(nCells);
 
    double varianceCorrection = (double)nCells / (double)(nCells-1);
    double etaVariance = std::max(m_etaPhiLowerLimit,varianceCorrection * (etaSum2/static_cast<double>(nCells) - m_etaMean*m_etaMean));
    double phiVariance = std::max(m_etaPhiLowerLimit,varianceCorrection * (phiSum2/static_cast<double>(nCells) - m_phiMean*m_phiMean));
 
    return std::make_pair(etaVariance,phiVariance);
}