在公式编号 LaTeX 中组合数字和字母

Question

我目前在 LaTeX 中有以下等式：

我试图在 LaTeX 中实现以下目标：

问题是我似乎无法让编号从 1a 开始。当我使用以下代码时，它从 0a 开始：

\renewcommand{\theequation}{\thesection\alph{equation}}

\begin{align}
\text{Level 1}&: y_{mdi} = \mu_{di} + e_{mdi}\\
\text{Level 2}&: \mu_{di} = \mu_i + r_{0di}\\
\text{Level 3}&: \mu_i = \gamma_{000} + u_{00i}
\end{align}

我试过使用

\setcounter{equation}{1}

但是该行代码改变了字母的起始位置（在本例中为 0b）。

编辑：我的文章（文档类 apa）中已经有 4 个部分；这段代码位于第 4 部分，因此从技术上讲它必须从 4a 开始。

Answer 1

您应该使用为此subequations提供的环境amsmath。

平均能量损失

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\section{1st subequation}

\begin{subequations}
\begin{align}
\text{Level 1}&: y_{mdi} = \mu_{di} + e_{mdi}\\
\text{Level 2}&: \mu_{di} = \mu_i + r_{0di}\\
\text{Level 3}&: \mu_i = \gamma_{000} + u_{00i}
\end{align}
\end{subequations}

\begin{subequations}
\begin{align}
\text{Level 1}&: y_{mdi} = \mu_{di} + e_{mdi}\\
\text{Level 2}&: \mu_{di} = \mu_i + r_{0di}\\
\text{Level 3}&: \mu_i = \gamma_{000} + u_{00i}
\end{align}
\end{subequations}

\section{2nd subequation}

\begin{subequations}
\begin{align}
\text{Level 1}&: y_{mdi} = \mu_{di} + e_{mdi}\\
\text{Level 2}&: \mu_{di} = \mu_i + r_{0di}\\
\text{Level 3}&: \mu_i = \gamma_{000} + u_{00i}
\end{align}
\end{subequations}

\section{No subequation}

\begin{align}
\text{Level 1}&: y_{mdi} = \mu_{di} + e_{mdi}\\
\text{Level 2}&: \mu_{di} = \mu_i + r_{0di}\\
\text{Level 3}&: \mu_i = \gamma_{000} + u_{00i}
\end{align}

\section{3rd subequation}

Here we want to start again from 4.
\setcounter{equation}{3}

\begin{subequations}
\begin{align}
\text{Level 1}&: y_{mdi} = \mu_{di} + e_{mdi}\\
\text{Level 2}&: \mu_{di} = \mu_i + r_{0di}\\
\text{Level 3}&: \mu_i = \gamma_{000} + u_{00i}
\end{align}
\end{subequations}

\end{document} 

输出：

Answer 2

\setcounter{equation}{0}在每个部分设置：

 \documentclass{article}
 \usepackage{amsmath}
\setcounter{equation}{0}
\renewcommand{\theequation}{\thesection\alph{equation}}
\begin{document}

\section{a}

\begin{align}
\text{Level 1}&: y_{mdi} = \mu_{di} + e_{mdi}\\
\text{Level 2}&: \mu_{di} = \mu_i + r_{0di}\\
\text{Level 3}&: \mu_i = \gamma_{000} + u_{00i}
\end{align}

\section{b}
\setcounter{equation}{0}
\begin{align}
\text{Level 1}&: y_{mdi} = \mu_{di} + e_{mdi}\\
\text{Level 2}&: \mu_{di} = \mu_i + r_{0di}\\
\text{Level 3}&: \mu_i = \gamma_{000} + u_{00i}
\end{align}

\section{c}
\setcounter{equation}{0}
\begin{align}
\text{Level 1}&: y_{mdi} = \mu_{di} + e_{mdi}\\
\text{Level 2}&: \mu_{di} = \mu_i + r_{0di}\\
\text{Level 3}&: \mu_i = \gamma_{000} + u_{00i}
\end{align}

\section{d}
\setcounter{equation}{0}
\begin{align}
\text{Level 1}&: y_{mdi} = \mu_{di} + e_{mdi}\\
\text{Level 2}&: \mu_{di} = \mu_i + r_{0di}\\
\text{Level 3}&: \mu_i = \gamma_{000} + u_{00i}
\end{align}
\end{document}

输出：

根据您的上次评论：

 \documentclass{article}
 \usepackage{amsmath}

\begin{document}

\section{a}

\begin{align}
\text{Level 1}&: y_{mdi} = \mu_{di} + e_{mdi}\\
\text{Level 2}&: \mu_{di} = \mu_i + r_{0di}\\
\text{Level 3}&: \mu_i = \gamma_{000} + u_{00i}
\end{align}

\begin{equation}
a=b
\end{equation}
\section{b}

\begin{equation}
a=b
\end{equation}
\begin{align}
\text{Level 1}&: y_{mdi} = \mu_{di} + e_{mdi}\\
\text{Level 2}&: \mu_{di} = \mu_i + r_{0di}\\
\text{Level 3}&: \mu_i = \gamma_{000} + u_{00i}
\end{align}

\section{c}

\begin{align}
\text{Level 1}&: y_{mdi} = \mu_{di} + e_{mdi}\\
\text{Level 2}&: \mu_{di} = \mu_i + r_{0di}\\
\text{Level 3}&: \mu_i = \gamma_{000} + u_{00i}
\end{align}

\section{d}
\setcounter{equation}{0}
\renewcommand{\theequation}{\thesection.\alph{equation}}
\begin{align}
\text{Level 1}&: y_{mdi} = \mu_{di} + e_{mdi}\\
\text{Level 2}&: \mu_{di} = \mu_i + r_{0di}\\
\text{Level 3}&: \mu_i = \gamma_{000} + u_{00i}
\end{align}
\end{document}