// =========================================================================
// @author Leonardo Florez Valencia
// @email florez-l@javeriana.edu.co
// =========================================================================
#include <fpa/Common/IncrementalMeanAndVariance.h>
#include <cmath>

// -------------------------------------------------------------------------
fpa::Common::IncrementalMeanAndVariance::
IncrementalMeanAndVariance( )
{
  this->Clear( );
}

// -------------------------------------------------------------------------
fpa::Common::IncrementalMeanAndVariance::
~IncrementalMeanAndVariance( )
{
}

// -------------------------------------------------------------------------
double fpa::Common::IncrementalMeanAndVariance::
GetMean( ) const
{
  return( this->m_M );
}

// -------------------------------------------------------------------------
double fpa::Common::IncrementalMeanAndVariance::
GetVariance( ) const
{
  return( this->m_V );
}

// -------------------------------------------------------------------------
double fpa::Common::IncrementalMeanAndVariance::
GetDeviation( ) const
{
  return( std::sqrt( this->m_V ) );
}

// -------------------------------------------------------------------------
unsigned long fpa::Common::IncrementalMeanAndVariance::
GetNumberOfSamples( ) const
{
  return( ( unsigned long )( this->m_N ) );
}

// -------------------------------------------------------------------------
void fpa::Common::IncrementalMeanAndVariance::
Clear( )
{
  this->m_M = double( 0 );
  this->m_V = double( 0 );
  this->m_N = double( 0 );
}

// -------------------------------------------------------------------------
void fpa::Common::IncrementalMeanAndVariance::
AddValue( double v )
{
  this->m_N += double( 1 );
  double d = v - this->m_M;
  if( this->m_N > double( 1 ) )
  {
    double o = ( this->m_N - double( 2 ) ) / ( this->m_N - double( 1 ) );
    this->m_V = ( o * this->m_V ) + ( ( d * d ) / this->m_N );
  }
  else
    this->m_V = double( 0 );
  this->m_M += d / this->m_N;
}

// eof - $RCSfile$