# How to change the "curliness" of Matrix brackets?

How can I get my matrix brackets to look like the above instead of:

My current one uses the following packages and has the latex:

\documentclass[12pt]{article}
\usepackage[a4paper]{geometry}
\usepackage{amsmath}
\usepackage{amssymb}
\begin{document}
$\vec{r}\cdot\begin{pmatrix} 3 \\2\\4 \end{pmatrix}=12$
\end{document}

• An unusual typographic objective. The reverse objective -- viz., how to make tall parentheses "more curvy@ -- is expressed far more frequently.
– Mico
Mar 4 at 12:15

\documentclass[12pt]{article}
$\vec{r}\cdot\left\lgroup\begin{matrix} 3 \\2\\4 \end{matrix}\right\rgroup=12$