PDFGaussian.cpp

#include "PDFGaussian.h"

namespace DirectGraphicalModels
{
void CPDFGaussian::reset(void)
{ 
    m_mu = 0;
    m_sigma2 = 0;
}

void CPDFGaussian::addPoint(Scalar point)
{ 
    if (m_nPoints == 0) m_mu = point[0];
    else {
        long double a = static_cast<double>(m_nPoints) / (m_nPoints + 1.0);
        m_mu = a * m_mu + (1.0 - a) * point[0];

        double cr = (point[0] - m_mu) * (point[0] - m_mu);
        m_sigma2 = cr + a *  (m_sigma2 - cr);
    }
    m_nPoints++;
}

double CPDFGaussian::getDensity(Scalar point) 
{ 
    double res = exp(- 0.5f * (point[0] - m_mu) * (point[0] - m_mu) / m_sigma2) /
        (sqrt(2.0f * m_sigma2 * Pi));
    
    return res;
}

void CPDFGaussian::saveFile(FILE *pFile) const
{ 
    fwrite(&m_mu,     sizeof(double), 1, pFile);
    fwrite(&m_sigma2, sizeof(double), 1, pFile);    
}

void CPDFGaussian::loadFile(FILE *pFile)
{ 
    fread(&m_mu,     sizeof(double), 1, pFile);
    fread(&m_sigma2, sizeof(double), 1, pFile);
}
}