The code I used to write
is this one
$$
X(m,n)=
\begin{cases}
x(n),\\
x(n-1)\\
x(n-1)
\end{cases}
$$
But I don't know how to write this one
Also, what if I want to write this
[Tex/LaTex] How to write cases with grouping braces on both left and right side, and split the condition into two lines in LaTeX
casesmath-mode
Related Solutions
use package mathtools. There is also a drcases environment
\documentclass{article}
\usepackage{mathtools}
\begin{document}
\[
\begin{rcases*}
E = m c^2 & foo \\
\int x-3\, dx & barbaz
\end{rcases*} y=f(x)
\]
\end{document}
Another solution (and numbering) with the empheq package (which loads mathtools, which loads amsmath):
\documentclass{article}
\usepackage[a4paper,margin=2.5cm]{geometry} % set page parameters
\usepackage{amsfonts, % for \mathbb and \mathcal macros
empheq}%
\numberwithin{equation}{subsection}
\setcounter{section}{1}
\setcounter{subsection}{1}
\begin{document}
\begin{subequations}
\begin{empheq}[left={\mathbb{E}(X)=\displaystyle\int_{-\infty}^{\infty} x\,dF(x)=\empheqlbrace}]{alignat = 2}
& \sum_{x \in \mathcal{X}} xf_{X}(x) =\sum_{x \in \mathcal{X}} x\mathbb{P}(X=x)
&\qquad & \text{if $X$ is discrete}, \\
& \int_{-\infty}^{\infty} xf_{X}(x)\,dx
& &\text{if $X$ is continuous}. \end{empheq}
\end{subequations}
\begin{subequations}
\begin{empheq}[left={\mathbb{E}(X)=\displaystyle∫_{-∞}^{∞} x\,dF(x)=\empheqlbrace}]{flalign}
& ∑_{x ∈ \mathcal{X}} xf_{X}(x) =∑_{x ∈ \mathcal{X}} x\mathbb{P}(X=x)
& &\text{if $X$ is discrete},&\hspace{5em} & \\
& ∫_{-∞}^{∞} xf_{X}(x)\,dx
&& \text{if $X$ is continuous}. \end{empheq}
\end{subequations}
\end{document}
Best Answer
If you want two conditions on different lines, can use a
\multirowfor the first column: