线性方程组的分组项

Question

我正在尝试排版一个线性方程组，我想将每个项对齐以便于阅读。我所能做到的最好方法是使用 alignat 环境。

以下是我所写的和我得到的结果：

\documentclass{article}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}

\begin{document}
    \begin{alignat}{6}
        &\text{Loop 1: } (\text{Z}_{\text{R}_1} + 
        \text{Z}_{\text{C}_1} + 
        \text{Z}_{\text{R}_2})&\text{I}_1(\omega) &- 
        (\text{Z}_{\text{C}_1} + 
        \text{Z}_{\text{R}_2})&\text{I}_2(\omega) 
        & & &= 1 \\
        &\text{Loop 2: } \qquad -(\text{Z}_{\text{R}_2} + 
        \text{Z}_{\text{C}_1})&\text{I}_1(\omega) &+ 
        (\text{Z}_{\text{L}_1} + \text{Z}_{\text{R}_4} + 
        \text{Z}_{\text{R}_2} + 
        \text{Z}_{\text{C}_1})&\text{I}_2(\omega) 
        &- (\text{Z}_{\text{L}_1})&\text{I}_3(\omega) &= 0 \\
        &\text{Loop 3: } & & - 
        (\text{Z}_{\text{L}_1})&\text{I}_2(\omega) 
        &- (\text{Z}_{\text{R}_3} + \text{Z}_{\text{C}_2}, + 
        \text{Z}_{\text{L}_1})&\text{I}_3(\omega) &= 0
    \end{alignat}
\end{document}

我将非常感激任何帮助我正确调整条款的帮助。

Answer 1

这是一个使用array环境的解决方案。

\documentclass{article}
\usepackage[a4paper,margin=2.5cm]{geometry}

\usepackage{array} % for '\newcolumntype' macro
\newcolumntype{C}{>{{}}c<{{}}} % for binary and relational operators
\newcolumntype{L}{>{$}l<{$}} % for the first (text) column

\begin{document}
\[
\setlength\arraycolsep{0pt}
\renewcommand{\arraystretch}{1.3}
\begin{array}{@{} L @{\quad} rCrCrCl @{}}
Loop 1:& (Z_{R_1} + Z_{C_1} + Z_{R_2})I_1(\omega) 
       &-&(Z_{C_1} + Z_{R_2})I_2(\omega) 
       & &
       &=& 1 \\
Loop 2:&-(Z_{R_2} + Z_{C_1})I_1(\omega) 
       &+&(Z_{L_1}+Z_{R_4}+Z_{R_2}+Z_{C_1})I_2(\omega) 
       &-&(Z_{L_1})I_3(\omega) 
       &=& 0 \\
Loop 3:& 
       & &(Z_{L_1})I_2(\omega) 
       &-&(Z_{R_3} + Z_{C_2} + Z_{L_1})I_3(\omega) 
       &=& 0
\end{array}
\]
\end{document}

Answer 2

我建议这样做，将“循环”放在 中\shortintertext。它要求几何图形具有适当的边距（您还可以使用 中的中等尺寸命令减小等式中的字体大小nccmath：

\documentclass{article}
\usepackage[showframe]{geometry}
\usepackage{mathtools}
\usepackage{amsfonts}
\usepackage{amssymb}

\begin{document}

    \begin{alignat}{4}
\shortintertext{Loop 1: \vskip -1ex}%
 (\text{Z}_{\text{R}_1} + \text{Z}_{\text{C}_1} + \text{Z}_{\text{R}_2}) & \text{I}_1(\omega) & {}- (\text{Z}_{\text{C}_1} + \text{Z}_{\text{R}_2}) & \text{I}_2(\omega)& & & & = 1 \\
\shortintertext{Loop 2: \vskip -4ex}%
 -(\text{Z}_{\text{R}_2} + \text{Z}_{\text{C}_1}) & \text{I}_1(\omega) & {}+ (\text{Z}_{\text{L}_1} + \text{Z}_{\text{R}_4} + \text{Z}_{\text{R}_2} + \text{Z}_{\text{C}_1}) & \text{I}_2(\omega) & {}- (\text{Z}_{\text{L}_1}) & \text{I}_3(\omega) & & = 0 \\
\shortintertext{Loop 3: \vskip -4ex} & & - (\text{Z}_{\text{L}_1})&\text{I}_2(\omega) &- (\text{Z}_{\text{R}_3} + \text{Z}_{\text{C}_2}, + \text{Z}_{\text{L}_1})&\text{I}_3(\omega) & & = 0
    \end{alignat}

\end{document}