Definition 6.2.2 (Spectral Radius).label For each element $x$ of an algebra $A$ over $\com$, the quantity
\begin{align*}\norm{x}{sp}=\sup\curl{\abs{\lam}:\lam\in\qspec{A}{x}}\end{align*}
is called the spectral radius of $x$
Definition 6.2.2 (Spectral Radius).label For each element $x$ of an algebra $A$ over $\com$, the quantity
is called the spectral radius of $x$