#ifndef _Stat_H
#define _Stat_H

//! $Id: Stat.H,v 1.1 2003/03/17 13:51:03 nbecker Exp $

#include <complex>

template<typename T>
struct Stat_t {
  typedef T value_t;
};

template<typename T>
struct Stat_t< std::complex<T> > {
  typedef typename std::complex<T>::value_type value_t;
};

template<typename T, typename cnt_t = int>
class Stat {
  typedef typename Stat_t<T>::value_t value_t;

  T sumX;
  value_t sumXsqr;
  cnt_t count;
public:
  Stat() :
    sumX (0),
    sumXsqr (0),
    count (0)
    {}

  void Reset() {
    sumX = 0;
    sumXsqr = 0;
    count = 0;
  }

  template<typename in_t>
  void Compute (in_t in, in_t inend) {
    for (; in != inend; in++)
      Compute (*in);
  }

  void Compute (T x) {
    operator += (x);
  }

  void operator += (T x) {
    count++;
    sumX += x;
    sumXsqr += (abs(x) * abs(x));
  }

  void operator() (T x) {
    operator += (x);
  }

  value_t Mean() const {
    if ( count > 0)
      return (sumX / count);
    else
      return ( 0.0 );
  }

  value_t Var() const {
    if (count > 1)
      return (sumXsqr - ((abs(sumX) * abs (sumX)) /  count)) / (count - 1);
    else
      return 0.0;
  }

  value_t StdDev() const {
    if (count <= 0)
	return 0;
    else
      return sqrt (Var());
  }

  value_t RMS() const {
    return StdDev();
  }

  cnt_t Cnt() const {
    return count;
  }

  value_t XsqrBar() const {
    return (sumXsqr / count);
  }
  
};

#endif