/*---------------------------------------------------------------
mahalanobisDistanceTo
---------------------------------------------------------------*/
double CPointPDFGaussian::mahalanobisDistanceTo( const CPointPDFGaussian & other, bool only_2D ) const
{
// The difference in means:
CMatrixDouble13 deltaX;
deltaX.get_unsafe(0,0) = other.mean.x() - mean.x();
deltaX.get_unsafe(0,1) = other.mean.y() - mean.y();
deltaX.get_unsafe(0,2) = other.mean.z() - mean.z();
// The inverse of the combined covs:
CMatrixDouble33 COV = other.cov;
COV += this->cov;
if (!only_2D)
{
CMatrixDouble33 COV_inv;
COV.inv(COV_inv);
return sqrt( deltaX.multiply_HCHt_scalar(COV_inv) );
}
else
{
CMatrixDouble22 C = COV.block(0,0,2,2);
CMatrixDouble22 COV_inv;
C.inv(COV_inv);
CMatrixDouble12 deltaX2 = deltaX.block(0,0,1,2);
return std::sqrt( deltaX2.multiply_HCHt_scalar(COV_inv) );
}
}
