quadraticCVCoefficent(D, dataElem, groupIdx, dataElemGroupIdx, m_dap)

function cvCoef = quadraticCVCoefficent(D, dataElem, groupIdx, dataElemGroupIdx, m_dap)
% Quadratic Cross Validation Coefficent

% MacLachlan, G.J. Discriminant Analysis and Statistical Pattern Recognition, Wiley

if groupIdx == dataElemGroupIdx
    p = m_dap.constants.numVar;
    n_i = m_dap.constants.numElemPerGrp(groupIdx);
    d_ii = (dataElem - m_dap.meanList{groupIdx}) * D * (dataElem - m_dap.meanList{groupIdx})';
    cvCoef.D = (n_i^2 * (n_i - 2) / (n_i - 1)) / ((n_i -1)^2 - n_i * d_ii);
    cvCoef.detD = (n_i - 2)^(p - 1) / (n_i^2 * (n_i - 1)^(p - 3)) * cvCoef.D;
else
    cvCoef.D = 1;
    cvCoef.detD = 1;
end