如何修改TikZ代码实现LaTeX公式的直角箭头注释？

DevOps 小满

2026-5-19

Got it! Let's adjust your existing TikZ code to swap those curved arrows for clean right-angle ones. I'll base this on a typical curved-arrow setup you might have used, so you can map it directly to your own code:

Modified Code with Right-Angle Arrows

\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}
\usetikzlibrary{positioning, tikzmark} % Keep your existing libraries

\begin{document}

\[
% Example formula with tikzmarks (adjust to match your original structure)
\sum_{i=1}^{\tikzmark{upper-limit}n} x_i = \underbrace{x_1 + x_2 + \dots + x_n}_{\tikzmark{brace}n \text{ terms}}
\]

\begin{tikzpicture}[overlay, remember picture, thick, ->]
    % Right-angle arrow for upper limit (first vertical, then horizontal)
    \node[above=15pt of pic cs:upper-limit, anchor=south] (limit-note) {*Number of elements to sum*};
    \draw (limit-note.south) |- (pic cs:upper-limit);

    % Right-angle arrow for underbrace (first horizontal, then vertical)
    \node[below=15pt of pic cs:brace, anchor=north] (brace-note) {*Expanded sum of all terms*};
    \draw (brace-note.north) -| (pic cs:brace);
\end{tikzpicture}

\end{document}

Key Changes to Your Original Code

Replace curved path commands (like bend left, curve to, or .. controls ..) with TikZ's built-in right-angle operators:
- |-: Draws a vertical segment first, then horizontal (perfect for arrows coming from above/below and turning toward the formula)
- -|: Draws a horizontal segment first, then vertical (ideal for arrows coming from left/right and turning toward the formula)
Keep your existing tikzmark or node positioning logic intact—you only need to update the arrow path itself.
If you need precise control over the corner of the right angle, you can manually define the turning point instead of using |-/-|, e.g.:
```
\draw (note.south) -- ++(0,-8pt) -- (pic cs:target); % Manual vertical then horizontal
```