
function m = momi2(f, R, parent)
    n11 = momcn(f, R, parent, 1, 1);
    n20 = momcn(f, R, parent, 2, 0);
    n02 = momcn(f, R, parent, 0, 2);
    
    m = (n20 .- n02) .^ 2 .+ 4 .* n11 .^ 2;
end
