Math & Science ⇒ Add connecting Arrows over Parts of an Equation

[luftbahnfahrer]

Is there a way to add arrows over (or under) different elements of an equation that would denote "swapping" those two parts?

Here's an example I created with a graphics editor (Inkscape) showing about what I am looking for:

equation-arrows.png (4.56 KiB) Viewed 7167 times

Thanks for any help!

[Stefan Kottwitz]

Hi,

welcome to the board!

With TikZ, you can define some pieces of the formula as nodes, and draw arrows between those nodes. Here's a complete compilable example, with comments what I'm doing:

Code: Select all

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows}% For nice arrow tips
% One style for all TikZ pictures for working with overlays:
\tikzset{every picture/.style=remember picture}
% Define a TikZ node for math content:
\newcommand{\mathnode}[1]{%
  \mathord{\tikz[baseline=(#1.base), inner sep = 0pt]{\node (#1) {$#1$};}}}
\begin{document}
\[
  \mathnode{A} \otimes B \otimes \mathnode{C} \otimes \mathnode{D}
    = C \otimes B \otimes A \otimes \mathnode{D}
\]
% Now we draw connections between defined nodes:
\begin{tikzpicture}[overlay]
  \path [>=stealth, <->, shorten <= 3pt, shorten >=3 pt]
    (A) edge [bend left=60] (C);
\end{tikzpicture}
\end{document}

math-nodes.png (2.72 KiB) Viewed 7161 times

Stefan

[luftbahnfahrer]

Thanks! Exactly what I was looking for.