MeanAndRMS.h

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/*
  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
*/
 
#ifndef MeanAndRMS_h
#define MeanAndRMS_h
 
#include <math.h>
 
class MeanAndRMS {
public :
  MeanAndRMS():m_w(0),m_wx(0),m_wx2(0) {};
  MeanAndRMS(const double xadd, const double weight=1):m_w(weight),m_wx(weight*xadd),m_wx2(weight*xadd*xadd) {};
  MeanAndRMS(const MeanAndRMS& ref):m_w(ref.m_w),m_wx(ref.m_wx),m_wx2(ref.m_wx2) {};
   
  MeanAndRMS& add(double xadd,double weight=1) {m_wx+=weight*xadd;m_wx2+=weight*xadd*xadd;m_w+=weight;return *this;};
  MeanAndRMS& operator+=(double xadd) {return add(xadd);};
  MeanAndRMS& operator-=(double xadd) {return add(-xadd);};
  MeanAndRMS& operator=(const MeanAndRMS& ref) {m_w=ref.m_w;m_wx=ref.m_wx;m_wx2=ref.m_wx2;return *this;};
  
  double sum_weight() const {return m_w;};
  double mean()       const {if(m_w!=0) return m_wx/m_w; else return 0;};
  double mean2()      const {double x=mean();return x*x;};
  double rms2()       const {if(m_w!=0) return m_wx2/m_w - mean2(); else return 0;};
  double rms()        const {double r2=rms2();if(r2>=0) return sqrt(r2); else return 0;};
  double mean_error() const {if(m_w>0) return rms()/sqrt(m_w); else return 0;};
  double rms_error()  const {if(m_w>0) return rms()/sqrt(2*m_w); else return 0;};
 
  operator double() const { return mean(); }
protected:
  double m_w;
  double m_wx,m_wx2;
};
 
#endif