如何对齐这些方程式并使图例集中

Question

如何对齐这两个方程式并使图例集中。

我的代码：

\usepackage{amsmath}        
\usepackage{amsfonts}
\newcommand{\ii}{{\rm i}}
\newcommand{\rev}{{\rm {rev}}}

\begin{equation}
        \label{eq:val015}
        \begin{aligned}
        %-------------
        \begin{cases}
          \alpha &= 0.117162 - \ii3.58144 \qquad \mathrm{para} \quad U_\rev=-0.15  \\
          \omega &= 0.629639 + \ii0.081002
        \end{cases} 
        %------------
        \\
        \begin{cases}
          \alpha &= -0.852386 - \ii4.43283 \qquad \mathrm{para} \quad U_\rev=-0.10  \\
          \omega &= -0.234147 + \ii0.654254
        \end{cases}
        \end{aligned}
          \end{equation}

结果：

我想实现这个目标：

Answer 1

除了 Barbara Beeton 的建议之外，还有一些改进的可能性，subequations包括siunitx：

\documentclass{article}
\usepackage{amsmath}
\usepackage{siunitx}
\usepackage{amsfonts}
\newcommand{\I}{\mathrm{i}}
\newcommand{\rev}{{\mathrm {rev}}}

\begin{document}

\begin{subequations}
\begin{align}
        \label{eq:val015}
        %-------------
        &\begin{cases}
          \alpha &= \num{0.117162} - \I\,\num{3.58144} \\
          \omega &= \num{0.629639} + \I\,\num{0.081002}
        \end{cases}
        & & \mathrm{para} \quad U_\rev=-0.15 \\[0.5ex]
        %------------
        &\begin{cases}
          \alpha &= -\num{0.852386} - \I\,\num{4.43283} \\
          \omega &= -\num{0.234147} + \I\, \num{0.654254}
        \end{cases}
        & & \mathrm{para} \quad U_\rev=-0.10
\end{align}
\end{subequations}

\begin{subequations}
\begin{align}
        \label{eq:val015}
        %-------------
        &\begin{cases}
          \alpha &= \num{0.117162} - \SI{3.58144}{i} \\
          \omega &= \num{0.629639} + \SI{0.081002}{i}
        \end{cases}
        & & \mathrm{para} \quad U_\rev=-0.15 \\[0.5ex]
        %------------
        &\begin{cases}
          \alpha &= -\num{0.852386} - \SI{4.43283}{i} \\
          \omega &= -\num{0.234147} + \SI{0.654254}{i}
        \end{cases}
        & & \mathrm{para} \quad U_\rev=-0.10
\end{align}
\end{subequations}

\end{document} 

Answer 2

align可以帮助调整事物。

\documentclass{article}
\usepackage{amsmath}        
\usepackage{amsfonts}
\newcommand{\ii}{{\rm i}}
\newcommand{\rev}{{\rm {rev}}}
\begin{document}
\begin{align}
        \label{eq:val015}
        %-------------
        &\begin{cases}
          \alpha &= 0.117162 - \ii3.58144 \\
          \omega &= 0.629639 + \ii0.081002
        \end{cases} 
        & \mathrm{para} \quad U_\rev=-0.15  \\
        %------------
        &\begin{cases}
          \alpha &= -0.852386 - \ii4.43283 \\
          \omega &= -0.234147 + \ii0.654254
        \end{cases}
        & \mathrm{para} \quad U_\rev=-0.10  
\end{align}
\end{document}

Answer 3

两个嵌套的aligneds；外部的aligneds 调整两个左括号\{和右侧元素，内部的aligneds 调整符号处的各两条单独的线=。

\documentclass{article}
\usepackage{amsmath}

\newcommand{\ii}{{\rm i}}
\newcommand{\rev}{{\rm {rev}}}
\begin{document}

\begin{equation}
        \label{eq:val0150}
        \begin{aligned}
        %-------------
        &\left\{
        \begin{aligned}
          \alpha &= 0.117162 - \ii3.58144 \\
          \omega &= 0.629639 + \ii0.081002
        \end{aligned} \right.
        &\qquad \mathrm{para} \quad U_\rev=-0.15  \\
        %------------
        &\left\{
        \begin{aligned}
          \alpha &= -0.852386 - \ii4.43283 \\
          \omega &= -0.234147 + \ii0.654254
        \end{aligned} \right. 
        &\qquad \mathrm{para} \quad U_\rev=-0.10         
        \end{aligned}
\end{equation}

\end{document}