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

enter image description here

My LaTeX expression looks like this:

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

but it happens that the double lines are short:

enter image description here

How can I extend the double vertical bar?

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up vote 9 down vote accepted

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

\min \left\| \begin{bmatrix} A\\ \vdots \\ C\end{bmatrix} \right\|

enter image description here

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What does one do if one doesn't need the corresponding \left delimiter? LaTeX complains if it is not present. – Abhinav Feb 11 at 21:12

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