If $x \| \underline{x} \| \infty = 1< i^{max} < n \: \: max \: \: ( \mid x1 \mid ) $ for the vector $\underline{x} = (x1, x2 \dots x_n)$ and $\| A \| \infty = x^{Sup} \frac{\| A \underline{x} \| \infty}{\| \underline{x} \| \infty}$ is the corresponding matrix norm, calculate $\| A \|_o$ for the matrix $A=\begin{bmatrix} 2 & 5 & 9 \\ 4 & 6 & 5 \\ 8 & 2 & 3 \end{bmatrix}$ using a known property of this norm.
Although this norm is very easy to calculate for any matrix, explain why the condition number is difficult (i.e. expensive) to calculate.