“…In general, the length of a vector (matrix) B ij may be position dependent; at a diagonal point A = diag(a 1 , a 2 , ..., a N ) the squared length of B is given by [1] that operator monotonicity implies that f maps R + → R + and is concave. The result of Morozova and Chentsov [32], completed and extended by Petz and Sudár [1,33], states that every monotone metric may be written in the form (2.16) up a proportionality constant. Conversely, this equation determines a monotone Riemannian metric, if the function f (t) = 1/c(t, 1) is: a) operator monotone, and b) self-transposed, f (1/t) = f (t)/t.…”