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Kullback – Leibler divergencia entre dos distribuciones gamma
Optar por parametrizar la distribución gamma Γ ( b , c )Γ(si,C)\Gamma(b,c) por el pdf g(x;b,c)=1Γ(c)xc−1bce-x/bg(x;b,c)=1Γ(c)Xc-1siCmi-X/ /sig(x;b,c) = \frac{1}{\Gamma(c)}\frac{x^{c-1}}{b^c}e^{-x/b} La divergencia Kullback-Leibler entreΓ(bq,cq)Γ(bq,cq)\Gamma(b_q,c_q)yΓ(bp,cp)Γ(bp,cp)\Gamma(b_p,c_p)viene dada por [1] como KLGa(bq,cq;bp,cp)=(cq−1)Ψ(cq)−logbq−cq−logΓ(cq)+logΓ(cp)+cplogbp−(cp−1)(Ψ(cq)+logbq)+bqcqbpKLGa(bq,cq;bp,cp)=(cq−1)Ψ(cq)−logbq−cq−logΓ(cq)+logΓ(cp)+cplogbp−(cp−1)(Ψ(cq)+logbq)+bqcqbp\begin{align} KL_{Ga}(b_q,c_q;b_p,c_p) &= (c_q-1)\Psi(c_q) - \log b_q - c_q - \log\Gamma(c_q) + \log\Gamma(c_p)\\ &\qquad+ c_p\log b_p - (c_p-1)(\Psi(c_q) + \log b_q) + \frac{b_qc_q}{b_p} …