在方程式中的数组中在 `\hline` 之前和之后添加间距

Question

我正在尝试在这个矩阵的前面和后面添加一点空间\hline：

\documentclass[a4paper,journal]{IEEEtran}
\usepackage[cmex10]{amsmath}
\interdisplaylinepenalty=2500


\usepackage{array}
\begin{document}
\begin{multline}
    \boldsymbol{J^{-1}} = \\   \left[ \begin{array}{ccc|ccc}
    \frac{\partial \delta_2}{\partial P_2} & \hdots & \frac{\partial \delta_n}{\partial P_2} &
    \frac{\partial \delta_2}{\partial Q_2} & \hdots & \frac{\partial \delta_n}{\partial Q_2} \\
    \vdots & \boldsymbol{J_{11}^\prime} & \vdots & \vdots & \boldsymbol{J_{21}^\prime} & \vdots \\
    \frac{\partial \delta_2}{\partial P_n} & \hdots & \frac{\partial \delta_n}{\partial P_n} &
    \frac{\partial \delta_2}{\partial Q_n} & \hdots & \frac{\partial \delta_n}{\partial Q_n} \\
    \hline
    \frac{1}{|V_2|}\frac{\partial |V_2|}{\partial P_2} & \hdots & \frac{1}{|V_n|}\frac{\partial |V_n|}{\partial P_2} &
    \frac{1}{|V_2|}\frac{\partial |V_2|}{\partial Q_2} & \hdots & \frac{1}{|V_n|}\frac{\partial |V_n|}{\partial Q_2} \\
     \vdots & \boldsymbol{J_{12}^\prime} & \vdots& \vdots & \boldsymbol{J_{22}^\prime} & \vdots \\
    \frac{1}{|V_2|}\frac{\partial |V_2|}{\partial P_n} & \hdots & \frac{1}{|V_n|}\frac{\partial |V_n|}{\partial P_n} &
     \frac{1}{|V_2|}\frac{\partial |V_2|}{\partial Q_n} & \hdots & \frac{1}{|V_n|}\frac{\partial |V_n|}{\partial Q_n} \\ 
    \end{array} \right]
    \\\label{eq:Jinv}
\end{multline}
\end{document}

输出：

目前，我已经这样做了：

... \\[0.5em]
\hline
&&&&&\\[-0.8em]
...

哪个有效：

但有点混乱。有没有更干净的方法来做到这一点？

Answer 1

您可以定义几个新命令。我不确定这是否比您自己的解决方案更好，但这是一种替代方法。

其中两个新命令是\bottomstrut和\topstrut。第三个命令将这两个命令与换行符和 组合起来，hline以适应多行环境。以下两个是示例：

\documentclass[a4paper,journal]{IEEEtran}
\usepackage[cmex10]{amsmath}
\interdisplaylinepenalty=2500

\newcommand{\bottomstrut}[1]{\rule[-#1]{0pt}{#1}}
\newcommand{\topstrut}[1]{\rule{0pt}{#1}}
\newcommand{\dividerline}[2]{\bottomstrut{#1}\\\hline\topstrut{#2}}


\usepackage{array}
\begin{document}

Example with \verb=\bottomstrut{2ex}\\\hline\topstrut{3ex}=

\begin{multline}
    \boldsymbol{J^{-1}} = \\   \left[ \begin{array}{ccc|ccc}
    \frac{\partial \delta_2}{\partial P_2} & \hdots & \frac{\partial \delta_n}{\partial P_2} &
    \frac{\partial \delta_2}{\partial Q_2} & \hdots & \frac{\partial \delta_n}{\partial Q_2} \\
    \vdots & \boldsymbol{J_{11}^\prime} & \vdots & \vdots & \boldsymbol{J_{21}^\prime} & \vdots \\
    \frac{\partial \delta_2}{\partial P_n} & \hdots & \frac{\partial \delta_n}{\partial P_n} &
    \frac{\partial \delta_2}{\partial Q_n} & \hdots & \frac{\partial \delta_n}{\partial Q_n} 
    \bottomstrut{2ex}\\\hline\topstrut{3ex}
    \frac{1}{|V_2|}\frac{\partial |V_2|}{\partial P_2} & \hdots & \frac{1}{|V_n|}\frac{\partial |V_n|}{\partial P_2} &
    \frac{1}{|V_2|}\frac{\partial |V_2|}{\partial Q_2} & \hdots & \frac{1}{|V_n|}\frac{\partial |V_n|}{\partial Q_2} \\
     \vdots & \boldsymbol{J_{12}^\prime} & \vdots& \vdots & \boldsymbol{J_{22}^\prime} & \vdots \\
    \frac{1}{|V_2|}\frac{\partial |V_2|}{\partial P_n} & \hdots & \frac{1}{|V_n|}\frac{\partial |V_n|}{\partial P_n} &
     \frac{1}{|V_2|}\frac{\partial |V_2|}{\partial Q_n} & \hdots & \frac{1}{|V_n|}\frac{\partial |V_n|}{\partial Q_n} \\ 
    \end{array} \right]
    \\\label{eq:Jinv:1}
\end{multline}

Example with \verb=\dividerline{2ex}{3ex}=

\begin{multline}
    \boldsymbol{J^{-1}} = \\   \left[ \begin{array}{ccc|ccc}
    \frac{\partial \delta_2}{\partial P_2} & \hdots & \frac{\partial \delta_n}{\partial P_2} &
    \frac{\partial \delta_2}{\partial Q_2} & \hdots & \frac{\partial \delta_n}{\partial Q_2} \\
    \vdots & \boldsymbol{J_{11}^\prime} & \vdots & \vdots & \boldsymbol{J_{21}^\prime} & \vdots \\
    \frac{\partial \delta_2}{\partial P_n} & \hdots & \frac{\partial \delta_n}{\partial P_n} &
    \frac{\partial \delta_2}{\partial Q_n} & \hdots & \frac{\partial \delta_n}{\partial Q_n} 
    \dividerline{2ex}{3ex}
    \frac{1}{|V_2|}\frac{\partial |V_2|}{\partial P_2} & \hdots & \frac{1}{|V_n|}\frac{\partial |V_n|}{\partial P_2} &
    \frac{1}{|V_2|}\frac{\partial |V_2|}{\partial Q_2} & \hdots & \frac{1}{|V_n|}\frac{\partial |V_n|}{\partial Q_2} \\
     \vdots & \boldsymbol{J_{12}^\prime} & \vdots& \vdots & \boldsymbol{J_{22}^\prime} & \vdots \\
    \frac{1}{|V_2|}\frac{\partial |V_2|}{\partial P_n} & \hdots & \frac{1}{|V_n|}\frac{\partial |V_n|}{\partial P_n} &
     \frac{1}{|V_2|}\frac{\partial |V_2|}{\partial Q_n} & \hdots & \frac{1}{|V_n|}\frac{\partial |V_n|}{\partial Q_n} \\ 
    \end{array} \right]
    \\\label{eq:Jinv:2}
\end{multline}
\end{document}