是否可以注释方程式（即箭头符号/花括号）来定义每个变量？

Question

我有一个很简单的问题。我想知道是否有可能在 LaTeX 中做这样的事情：

但格式更漂亮一些。

它不一定是箭头。只是某种形式的注释标记。

Answer 1

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{tikzmark}

\begin{document}
\[
\tikzmarknode{A}{f}(\tikzmarknode{B}{5}) = \tikzmarknode{C}{25}
\begin{tikzpicture}[overlay, remember picture,shorten <=1mm,
                    nodes={inner sep=1pt, align=center, font=\footnotesize}]
\draw (A.south) -- ++ (-1,-1) node[below] {The\\ machine};
\draw (B.south) -- ++ (.2,-1) node[below] {When\\ given 5};
\draw (C.south) -- ++ (.8,-1) node[below] {Gives\\ us 25};
\end{tikzpicture}
\vspace{3ex}
\]
\end{document}

为了获得以下结果，您需要至少编译两次 MWE（最小工作示例）！

附录： 红色箭头所示：

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows.meta, tikzmark}

\begin{document}
\[
\tikzmarknode{A}{f}(\tikzmarknode{B}{5}) = \tikzmarknode{C}{25}
\begin{tikzpicture}[overlay, remember picture,shorten <=1mm,
                    nodes={inner sep=1pt, align=center, font=\footnotesize},
                    every path/.style = {draw=red, Stealth-}] % <---
\draw (A.south) -- ++ (-1,-1) node[below] {The\\ machine};
\draw (B.south) -- ++ (.2,-1) node[below] {When\\ given 5};
\draw (C.south) -- ++ (.8,-1) node[below] {Gives\\ us 25};
\end{tikzpicture}
\vspace{3ex}
\]
\end{document}