下面是我编写的代码:
\begin{equation}
\begin{aligned}
Si \,\,\,\,\,\, \varepsilon Q_s \geq \Delta Q_s\\
Si \,\,\,\,\,\, \varepsilon Q_s \leq -\Delta Q_s\\
Si \,\,\,\,\,\, \varepsilon P_s \geq \Delta P_s\\
Si \,\,\,\,\,\, -\Delta P_s \leq \varepsilon P_s \leq \Delta P_s\\
Si \,\,\,\,\,\, \varepsilon P_s \leq -\Delta P_s
\end{aligned}
\end{equation}
答案1
可以用cases
and来实现alignedat
。由于您似乎用法语书写,因此我擅自使用了法语不等号。我还建议使用第二种对齐方式,在我看来,它看起来更浅:\documentclass[9pt]{extbook}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{array}
\usepackage{amsfonts,amssymb}
\usepackage{empheq}
\usepackage[francais]{babel}
\def\fgeq{\geqslant}
\def\fleq{\geqslant}
\begin{document}
\begin{equation}
\begin{cases}
\begin{alignedat}{3}
&\text{Si} & \enspace & \varepsilon Q_s \fgeq \Delta Q_s & \quad\implies & H_Q = 1\\
& \text{Si} & & \varepsilon Q_s \fleq -\Delta Q_s & \implies & H_Q = -1\\
& \text{Si} & & \varepsilon P_s \fgeq \Delta P_s & \implies & H_P = 1\\
& \text{Si} & & -\Delta P_s \fleq \varepsilon P_s \fleq \Delta P_s & \implies & H_P = 0\\
& \text{Si} & & \varepsilon P_s \fleq -\Delta P_s & \implies & H_P = -1
\end{alignedat}
\end{cases}
\end{equation}
\end{document}
答案2
您只需要一个cases
环境(由包提供):amsmath
\documentclass{article}
\usepackage{amsmath} % for 'cases' environment
\begin{document}
\begin{equation}
\begin{cases}
\text{Si } \varepsilon Q_s \geq \Delta Q_s & \Rightarrow H_Q=\phantom{-}1 \\
\text{Si } \varepsilon Q_s \leq -\Delta Q_s & \Rightarrow H_Q=-1 \\
\text{Si } \varepsilon P_s \geq \Delta P_s & \Rightarrow H_P=\phantom{-}1 \\
\text{Si }{-}\Delta P_s\leq\varepsilon P_s\leq\Delta P_s
& \Rightarrow H_P=\phantom{-}0\\
\text{Si } \varepsilon P_s \leq -\Delta P_s & \Rightarrow H_P=-1
\end{cases}
\end{equation}
\end{document}