MeanRMS.h

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/*
  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
*/
 
#include "cmath"
 
namespace MuonCalib {
 
    class MeanRMS {
    public:
        inline MeanRMS() : m_sum_x(0.), m_sum_x_sq(0.), m_n_ent(0) {}
        inline void Insert(double x) {
            m_sum_x += x;
            m_sum_x_sq += x * x;
            m_n_ent++;
        }
        inline double GetMean() const {
            if (m_n_ent == 0) return 0;
            return m_sum_x / static_cast<double>(m_n_ent);
        }
        inline double GetRMS() const {
            if (m_n_ent == 0) return 0;
            double mean = GetMean();
            return std::sqrt(m_sum_x_sq / static_cast<double>(m_n_ent) - mean * mean);
        }
        inline int GetN() const { return m_n_ent; }
 
    private:
        double m_sum_x;
        double m_sum_x_sq;
        int m_n_ent;
    };
}  // namespace MuonCalib