# How to typeset curly brackets in equations

Please, how can I typeset the equation in the attached picture.

• Welcome to TeX.SE! You make it easier to help people if you give some code, showing your tries. In this case I'd look at the mathtools manual. Look for cases, matrices and paired delimiters. Mar 10 at 7:38
• @Tee I have given a point of departure only because I do not want to redo all the typing. Mar 10 at 8:21
• @Denis thank you
– Tee
Mar 11 at 3:31

## 2 Answers

I'd like to suggest that you load the mathtools package for its dcases* environment and \coloneqq macro. And, do use bmatrix environments for the column vectors that are encased in square brackets.

\documentclass{article}
\usepackage{mathtools} % for dcases* env. and \coloneqq macro
\begin{document}
$G_{\chi}(\eta) \coloneqq \begin{dcases*} \bigl( [T_{u,1}^*, T_{u,2}^*],\tau_y,0,\eta_c \bigr) & if \tau_u=0 and \tau_y>0 \\[\jot] \bigl( \tau_u,[T_{y,1}^*, T_{y,2}^*],0,F_c^s(\eta) \bigr) & if \tau_u>0 and \tau_y=0 \\[\jot] \left\{ \begin{bmatrix} [T_{u,1}^*, T_{u,2}^*] \\ \tau_y \\ 0 \\ \eta_c \end{bmatrix}, \begin{bmatrix} \tau_u \\ [T_{y,1}^*, T_{y,2}^*] \\ 0 \\F_c^s(\eta) \end{bmatrix} \right\} & if \tau_u=0 and \tau_y=0 \end{dcases*}$
\end{document}


A point of departure could be

\documentclass[12pt]{article}
\usepackage{amsmath}
\begin{document}
\begin{equation*}
X =
\begin{cases}
\begin{Bmatrix}
\begin{bmatrix}
a & b\\
c & d
\end{bmatrix}
,
\begin{bmatrix}
A & B\\
D & C
\end{bmatrix}
\end{Bmatrix}
& \text{if $x=p$}  \\
0 & \text{otherwise}
\end{cases}
\end{equation*}
\end{document}


• Small suggestion: write \text{if $x=p$}, semantically if $x=p$ is the entire comment. If writing it this way one can also avoid situations like \text{if } x=p \text{ and } y>0 and instead write the straight forward \text{if $x=p$ and $y>0$} Mar 10 at 8:10
• @daleif Thanks for the suggestion. I am implementing it in my proto-answer. Mar 10 at 8:13