# How do I type large set brackets that look like this

How can I get the set brackets to look like this?

• Welcome to TeX.SX! See if How to make brackets larger? answers your question. Oct 10, 2015 at 22:43
• See also bigger parentheses in equations Oct 10, 2015 at 22:45
• "to look like this?" instead of like what? Please clarify, e.g. by showing us what you've come up with so far. Right now it seems like you're asking about some of the most basic tools found in every tutorial. Oct 10, 2015 at 22:54

You can use \left\{ and \right\}. They autosize your brackets around your content and the item that follows them, in this case \{, is the delimiter.

• Note that \left{ is illegal. Oct 10, 2015 at 23:01

With mathtools you can define a \set command, which accepts an optional argument: \big, \Big,&c. to control the size of the brackets. The starred version is equivalent of a pair of \left ··· \right around the braces.

As to the separator, @egreg pointed there's a small difference between : and \colon. I propose both, so the choice depends on one's taste:

\documentclass[12pt]{article}

\usepackage{mathtools}
\DeclarePairedDelimiter\set{\{}{\}}
\newcommand\numberset[1]{\mathbf{#1}}
\newcommand\Real{\numberset{R}}

\begin{document}

\begin{align*}
& \set*{\begin{pmatrix}x + 2y\\x\\-y\end{pmatrix}: x, y\in\Real} \\[3ex]
&\set*{\begin{pmatrix}x + 2y\\x\\-y\end{pmatrix}\colon x, y\in\Real}
\end{align*}

\end{document}


• Should \colon be used instead of :?
– Mico
Oct 11, 2015 at 0:21
• You're right. Not sure may people will see the difference (~0.6pt more horizontal spacing after the colon), nor that's worth the typing (unless we get it it automatically in the place of : using xparse. At any rate I changed it. Thanks for your eagle-eye ;o) Oct 11, 2015 at 0:38
• @Mico No; here the colon is used as a relation symbol, so : is the right input; \colon leaves a small space at its left and a larger space at its right. Oct 11, 2015 at 10:35
• @egreg: I noticed that, and that's why I ultimately preferred it… Oct 11, 2015 at 11:41