如何创建矩形框架？

Question

我想在类似附图的矩形框内写下算法的步骤？

另外，我想把它的标题“算法......”放在左上角，就像图中的“梯度方法”一样。

提前感谢您的帮助！

Answer 1

一个可能的解决方案：只需创建一个表格单元格：

\documentclass{article}
\usepackage[table,xcdraw]{xcolor}
\usepackage{lipsum}
\usepackage{amssymb}
\usepackage{enumitem}

\begin{document}
    
    \begin{table}[]
        \renewcommand{\arraystretch}{1.25}
        \centering
        %\caption{}
        \label{tab:my-table}
        \begin{tabular}{|
                >{\columncolor[HTML]{EFEFEF}}p{0.9\textwidth} |}
            \hline
            \textbf{The Gradient Method}\\
            \\
            \textbf{Input:} $\epsilon>0$\\
            \textbf{Initialization:} Pick $x_0 \in \mathbb{R}^{n}$ arbitrarily.\\
            \textbf{General step:} For any $k=0,1,2...$ execute the following steps:
            \begin{enumerate}[label=(\alph*)]
                \item Pick a stepsize $t_k$ by a line search procedure on the function.
                \begin{center}$g(t)=f(x_k-t\triangledown f(x_k))$\end{center}
                \item Set $x_{k+1}=x_k+t_k\triangledown f(x_k)$
                \item If $\parallel \triangledown f(x_{k+1}) \parallel \leq \epsilon$, then STOP and $x_{k+1}$ is the output.
            \end{enumerate}
            \\ \hline
        \end{tabular}
    \end{table}
    
\end{document}

Answer 2

这里有一个 tcolorbox 解决方案：

% https://tex.stackexchange.com/questions/581381/how-to-create-a-rectangular-framework
\documentclass{article}
\usepackage[table,xcdraw]{xcolor}
\usepackage{lipsum}
\usepackage{amssymb}
\usepackage{enumitem}

\usepackage{tcolorbox}
\tcbuselibrary{skins}

\begin{document}
\begin{table}[]
  \renewcommand{\arraystretch}{1.25}
  \centering
  % \caption{}
  \label{tab:my-table}
  \begin{tabular}{|
    >{\columncolor[HTML]{EFEFEF}}p{0.9\textwidth} |}
    \hline
    \textbf{The Gradient Method}\\
    \\
    \textbf{Input:} $\epsilon>0$\\
    \textbf{Initialization:} Pick $x_0 \in \mathbb{R}^{n}$ arbitrarily.\\
    \textbf{General step:} For any $k=0,1,2...$ execute the following steps:
    \begin{enumerate}[label=(\alph*)]
    \item Pick a stepsize $t_k$ by a line search procedure on the function.
      \begin{center}$g(t)=f(x_k-t\triangledown f(x_k))$\end{center}
    \item Set $x_{k+1}=x_k+t_k\triangledown f(x_k)$
    \item If $\parallel \triangledown f(x_{k+1}) \parallel \leq \epsilon$, then STOP and $x_{k+1}$ is the output.
    \end{enumerate}
    \\ \hline
  \end{tabular}
\end{table}

\begin{tcolorbox}[enhanced, title=The Gradient Method,%
  colbacktitle=black!20, coltitle=black, colframe=black, sharp corners,%
  colback=black!10, boxrule=.5pt, titlerule=0pt,%
  ]
  \textbf{Input:} $\epsilon>0$\\
  \textbf{Initialization:} Pick $x_0 \in \mathbb{R}^{n}$ arbitrarily.\\
  \textbf{General step:} For any $k=0,1,2\ldots$ execute the following steps:
  \begin{enumerate}[label= (\alph*)]
  \item Pick a stepsize $t_k$ by a line search procedure on the function.
    \begin{center}$g(t)=f(x_k-t\triangledown f(x_k))$\end{center}
  \item Set $x_{k+1}=x_k+t_k\triangledown f(x_k)$
  \item If $\parallel \triangledown f(x_{k+1}) \parallel \leq \epsilon$, then STOP and $x_{k+1}$ is the output.
  \end{enumerate}
\end{tcolorbox}
\end{document}