Operator Convex Functions of Several Variables
Operator Convex Functions of Several Variables
The functional calculus for functions of several variables associates to each tuple x= (x_1, ⋯, x_k) of selfadjoint operators on Hilbert spaces H_1, ⋯,H_k an operator f(x) in the tensor product B(H_1)⊗ ⋯ ⊗B(H_k) . We introduce the notion of generalized Hessian matrices associated with f . Those matrices are …