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逐项列表中的子方程编号

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逐项列表中的子方程编号

这是我为一组等效定义生成的半正定性。

\documentclass[10pt]{article}

% for fancy math
\usepackage{amsmath}

% rank operator
\DeclareMathOperator*{\rank}{rank}

% Matrix transpose
\newcommand{\trans}[1]{\ensuremath{{#1}^\top}}

% for extra space at the end of abbreviation
\usepackage{xspace}

% positive semi-definite
\newcommand{\psd}{\textsc{psd}\xspace}

% boldface uppercase letters for matrices
\newcommand{\Abf}{\ensuremath{\mathbf A}}
\newcommand{\Bbf}{\ensuremath{\mathbf B}}

% boldface lowercase letters for vectors
\newcommand{\xbf}{\ensuremath{\mathbf x}}

% for math blackboard font
\usepackage{amssymb}
% set of real numbers
\newcommand{\Rbb}{\ensuremath{\mathbb R}}

\usepackage{palatino}
\usepackage[sc]{mathpazo}

\begin{document}
\noindent
For any real symmetric matrcies $\Abf$ such that $\rank(\Abf_{n\times n})=r$,
the following statements are equivalent
and any one of them can serve as the definition of
\emph{positive semi-definite} (\psd) matrices.
\begin{itemize}
  \item $\trans\xbf \Abf\xbf \geq 0$ for any non-zero vector
    $\xbf\in\Rbb^{n\times 1}$.
    \hfill\refstepcounter{equation}\textup{(\theequation)}%
  \item All the $n$ eigenvalues of $\Abf$ are non-negative.
    \hfill\refstepcounter{equation}\textup{(\theequation)}%
  \item $\Abf=\trans\Bbf \Bbf$ for some $\Bbf$ with $\rank(\Bbf)=r$.
    \hfill\refstepcounter{equation}\textup{(\theequation)}%
\end{itemize}

\end{document}

在此处输入图片描述

由于这些定义都是等价的，我想将它们编号为 (1a)、(1b) 和 (1c)，而不是 (1)、(2)、(3)。我不确定是否可以使用subequations环境，因为我想将三个不同的定义保留为逐项列表中的文本。

有什么建议么？

答案1

只需添加：

\begin{subequations}
...
\end{subequations}

在您的周围itemize环境中。

答案2

这是这种布局的另一种视图，可避免手动插入方程编号：

在此处输入图片描述

\documentclass[10pt]{article}

% for fancy math
\usepackage{amsmath}

% rank operator
\DeclareMathOperator*{\rank}{rank}

% Matrix transpose
\newcommand{\trans}[1]{\ensuremath{{#1}^\top}}

% for extra space at the end of abbreviation
\usepackage{xspace}

% positive semi-definite
\newcommand{\psd}{\textsc{psd}\xspace}

% boldface uppercase letters for matrices
\newcommand{\Abf}{\ensuremath{\mathbf A}}
\newcommand{\Bbf}{\ensuremath{\mathbf B}}

% boldface lowercase letters for vectors
\newcommand{\xbf}{\ensuremath{\mathbf x}}

% for math blackboard font
\usepackage{amssymb}
% set of real numbers
\newcommand{\Rbb}{\ensuremath{\mathbb R}}

\usepackage{palatino}
\usepackage[sc]{mathpazo}

\newcommand{\mathitem}{\hspace*{1.2em}&\bullet\hspace*{\labelsep}}
\begin{document}
\noindent
For any real symmetric matrcies $\Abf$ such that $\rank(\Abf_{n\times n})=r$,
the following statements are equivalent
and any one of them can serve as the definition of
\emph{positive semi-definite} (\psd) matrices.
\begin{itemize}
  \item $\trans\xbf \Abf\xbf \geq 0$ for any non-zero vector
    $\xbf\in\Rbb^{n\times 1}$.
    \hfill\refstepcounter{equation}\textup{(\theequation)}%
  \item All the $n$ eigenvalues of $\Abf$ are non-negative.
    \hfill\refstepcounter{equation}\textup{(\theequation)}%
  \item $\Abf=\trans\Bbf \Bbf$ for some $\Bbf$ with $\rank(\Bbf)=r$.
    \hfill\refstepcounter{equation}\textup{(\theequation)}%
\end{itemize}

\noindent
For any real symmetric matrcies $\Abf$ such that $\rank(\Abf_{n\times n})=r$,
the following statements are equivalent
and any one of them can serve as the definition of
\emph{positive semi-definite} (\psd) matrices.
\begin{subequations}
\makeatletter\@fleqntrue\makeatother
\begin{align}
  \mathitem \text{$\trans\xbf \Abf\xbf \geq 0$ for any non-zero vector
    $\xbf\in\Rbb^{n\times 1}$.} \\
  \mathitem \text{All the $n$ eigenvalues of $\Abf$ are non-negative.} \\
  \mathitem \text{$\Abf=\trans\Bbf \Bbf$ for some $\Bbf$ with $\rank(\Bbf)=r$.}
\end{align}
\end{subequations}

\end{document}

align这个想法是在环境中设置一个常规subequations，暂时将其刷新到左边距（通过激活\@fleqntrue）。如果您想要增加元素之间的间隙（因为它们在 下稍微紧密一些align），请\\[<len>]在指定 的位置使用<len>。

答案3

为什么不直接列出清单呢：

\begin{itemize}
  \item $\trans\xbf \Abf\xbf \geq 0$ for any non-zero vector
    $\xbf\in\Rbb^{n\times 1}$.
    \hfill\refstepcounter{equation}\textup{(\theequation a)}%
  \item All the $n$ eigenvalues of $\Abf$ are non-negative.
    \hfill\refstepcounter{equation}\textup{(\theequation b)}%
  \item $\Abf=\trans\Bbf \Bbf$ for some $\Bbf$ with $\rank(\Bbf)=r$.
    \hfill\refstepcounter{equation}\textup{(\theequation c)}%
\end{itemize}

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