How to check if a matrix transfer function is in Hardy-infinity space?

Question

Just like the question says. For instance if I have a matrix transfer function $$\mathbf{G}(s) = \begin{bmatrix}s & -s \\ T & s \\ \end{bmatrix}$$ where $T$ is a positive constant, how can I tell whether it is in Hardy-infinity space? Is there any other way than just verifying that $||\mathbf{G}(s)||_{\infty} < \infty$