Since directly typing \footnote{...}
in math mode is not allowed, the common approach is to type \footnotemark
in the math and write \footnotetext{...}
after the math. However, when the math is located to the bottom of a page, the line containing \footnotetext{...}
is on the second page, causing the misplacement of the actual footnote. Example:
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{pgffor} % for \foreach
\begin{document}
\foreach \x in {1,...,43}
{The \x th fictional space-taking line.
}
\[
fictional + math + formula \footnotemark
\]\footnotetext{This is a fictional footnote. See the weird behavior?}
\end{document}
yields
\footnote
inside the equation environment should just work in this case. It would not work inside any of theamsmath
math environments or inside e.g.\text{}
within the equation though.