Extend double vertical bar

Question

I'm trying to write an expression in math mode similar to this formula:

My LaTeX expression looks like this:

\min \| \begin{array}{c} ... \end{array} \|

but it happens that the double lines are short:

How can I extend the double vertical bar?

Answer 1

Use the \left ... \right construction. See page 60 and table 3.8 of the Not so short intro. to LaTeX for further details.

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\[
\min \left\| \begin{bmatrix} A\\ \vdots \\ C\end{bmatrix} \right\|
\]
\end{document}