Statistic.h

// -*- C++ -*-
//
// Statistic.h is a part of Herwig - A multi-purpose Monte Carlo event generator
// Copyright (C) 2002-2019 The Herwig Collaboration
//
// Herwig is licenced under version 3 of the GPL, see COPYING for details.
// Please respect the MCnet academic guidelines, see GUIDELINES for details.
//
#ifndef HERWIG_Statistic_H
#define HERWIG_Statistic_H
#include <cmath>
 
//
// This is the declaration of the Statistic class.
//
 
namespace Herwig {
 
class Statistic {
 
public:
 
  Statistic() : _n(0), _xsum(0.), _x2sum(0.),
                _min(-1e100), _max(1e100) {}
 
  double minimum() const { return _min; }
 
  double maximum() const { return _max; }
 
  void operator+=(double input) 
  {
    ++_n;
    _xsum  += input;
    _x2sum += input * input;
    if (_min > input || _n == 1) _min = input;
    if (_max < input || _n == 1) _max = input;
  }
 
  unsigned int numberOfPoints() const { return _n; }
  
  double mean() const 
  {
    return _n > 0  ?  _xsum / _n : 0.; 
  }
 
  double mean_stdDev() const { return std::sqrt(mean_var()); }
 
  double mean_var() const 
  {
    return _n > 1  ?  var() / _n : 0.; 
  }
 
  double stdDev() const { return std::sqrt(var()); }
 
  double var() const 
  { 
    return _n > 1  ?  ( _x2sum - _xsum*_xsum/_n ) / ( _n - 1 ) : 0.; 
  }
 
  double total() const { return _xsum; }
 
private:
 
  unsigned int _n;
 
  double _xsum;
 
  double _x2sum;
 
  double _min;
  
  double _max;
};
 
}
 
#endif /* HERWIG_Statistic_H */