3.21 ( ) An alternative way to derive the result (3.92) for the optimal value of in the evidence framework is to make use

3.21 ( ) An alternative way to derive the result (3.92) for the optimal value of α in the evidence framework is to make use of the identity d

dα

ln |A| = Tr



A−1 d dα

A



. (3.117)

Prove this identity by considering the eigenvalue expansion of a real, symmetric matrix A, and making use of the standard results for the determinant and trace of A expressed in terms of its eigenvalues (Appendix C). Then make use of (3.117) to derive (3.92) starting from (3.86).