如何用罗马数字枚举命令 \numcases 的项目

Question

我的代码

\begin{subequations}
    \begin{numcases}{}
    q - 1 & \text{se $\psi = \psi_0$ e $\chi = \chi_0$} \label{roman*}  \\
    -1    & \text{se $\psi = \psi_0$ e $\chi \neq \chi_0$} \\
    0     & \text{se $\psi \neq \psi_0$ e $\chi = \chi_0$} \\
    & \text{Se $\chi \neq \chi_0$ e 
        $\psi \neq \psi_0 \Rightarrow \lvert G(\psi,\chi)\rvert = \sqrt{q}$}
    \end{numcases}
\end{subequations}

它列出了（1a），（1b），我想放“i”，“ii”...

Answer 1

subequations如果您只想要单层枚举，则不需要。无论您选择哪种方式，都需要重新定义\theequation：

\documentclass{article}

\usepackage{amsmath,cases}

\begin{document}

Perhaps you're looking for
\begin{subequations}
  \renewcommand{\theequation}{\theparentequation\roman{equation}}%
  \begin{numcases}{}
    q - 1 & \text{se $\psi = \psi_0$ e $\chi = \chi_0$}    \\
    -1    & \text{se $\psi = \psi_0$ e $\chi \neq \chi_0$} \\
    0     & \text{se $\psi \neq \psi_0$ e $\chi = \chi_0$} \\
          & \text{Se $\chi \neq \chi_0$ e 
                  $\psi \neq \psi_0 \Rightarrow \lvert G(\psi,\chi)\rvert = \sqrt{q}$}
  \end{numcases}
\end{subequations}

But you could also be interested in%
\renewcommand{\theequation}{\roman{equation}}
\begin{numcases}{}
  q - 1 & \text{se $\psi = \psi_0$ e $\chi = \chi_0$}    \\
  -1    & \text{se $\psi = \psi_0$ e $\chi \neq \chi_0$} \\
  0     & \text{se $\psi \neq \psi_0$ e $\chi = \chi_0$} \\
        & \text{Se $\chi \neq \chi_0$ e 
                $\psi \neq \psi_0 \Rightarrow \lvert G(\psi,\chi)\rvert = \sqrt{q}$}
\end{numcases}

\end{document}

Answer 2

我不推荐cases和numcases，而是empheq。

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[italian]{babel}

\usepackage{amsmath,empheq}

\begin{document}

\begin{subequations}\label{general}
\renewcommand{\theequation}{\theparentequation\,\roman{equation}}%
\begin{empheq}[left=\empheqlbrace]{alignat=2}
 & q-1  &\qquad& \text{se $\psi = \psi_0$ e $\chi = \chi_0$} \\
 & {-1} &      & \text{se $\psi = \psi_0$ e $\chi \neq \chi_0$} \\
 & 0    &      &\text{se $\psi \neq \psi_0$ e $\chi = \chi_0$} \\
 &      &      &\text{Se $\chi \neq \chi_0$ e 
                $\psi \neq \psi_0 \Rightarrow
                \lvert G(\psi,\chi)\rvert = \sqrt{q}$}
\end{empheq}
\end{subequations}

\end{document}