P ~ N(μ₁, σ₁²)
Q ~ N(μ₂, σ₂²)
DKL(P‖Q) = 0.0000
KL for univariate normals: \( D_{KL}(P\,\|\,Q) = \tfrac{1}{2}\big[(\sigma_1^2 + (\mu_1-\mu_2)^2)/\sigma_2^2 - 1 + \ln(\sigma_2^2/\sigma_1^2)\big] \)