In your blog post you have  Shouldn't that be  I think in your formulation `tr(Σ(Χ))` should be `tr(Σ^(-1)(Χ))` `μ(Χ)^(Τ) μ(Χ)` should be `μ(Χ)^(Τ) Σ^(-1)(Χ) μ(Χ)` `-log(det(Σ(Χ)))` should be `+log(det(Σ(Χ)))`