source: trunk/src/RegressionNaive.cc @ 235

// $Id: RegressionNaive.cc 235 2005-02-21 14:53:48Z peter $


#include "RegressionNaive.h"

#include "Averager.h"
#include "Regression.h"
#include "vector.h"
#include "WeightedAverager.h"

#include <iostream>


namespace theplu {
namespace statistics {

  
  RegressionNaive::RegressionNaive(void)
    : Regression(), m_(0.0), m_err_(0.0)
  {
  }

  void RegressionNaive::fit(const gslapi::vector& x, const gslapi::vector& y)
  {
    Averager a;
    for (size_t i=0; i<y.size(); i++)
      a.add(y(i));
    m_=a.mean();
    s2_=a.variance();
    m_err_=a.standard_error();
  }

  void RegressionNaive::fit(const gslapi::vector& x,
                            const gslapi::vector& y,
                            const gslapi::vector& w)
  {
    WeightedAverager a;
    for (size_t i=0; i<y.size(); i++)
      a.add(y(i), w(i));
    m_=a.mean();
    m_err_=a.standard_error();
    s2_=m_err_*m_err_*w.sum(); 
  }

  void RegressionNaive::predict(const double x, double& y, double& y_err, 
                                const double w) 
  { 
    x_ = x;
    y = m_; 
    y_err = sqrt(m_err_*m_err_ + s2_/w);
  }
  
  std::ostream& RegressionNaive::print(std::ostream& s) const
  {
    s << x_ << "\t" 
      << m_ << "\t"
      << sqrt(m_err_*m_err_ + s2_);
    return s;
  }
  
  std::ostream& RegressionNaive::print_header(std::ostream& s) const
  {
    s << "# column 1: x\n"
      << "# column 2: y\n"
      << "# column 3: y_err";
    return s;
  }
  
}} // of namespace cpptools and namespace theplu