This is a preview. Log in through your library . Abstract Let f be a positive real-valued function defined on an interval I ⊆ R. The function f is said to be log-convex if logf is convex on I. In this ...

For a rational matrix function Φ with poles outside the unit circle, we estimate the degree of the unique superoptimal approximation 𝒜Φ by matrix functions analytic in the unit disk. We obtain sharp ...