# Howto place footnote next to equation

Consider the following fragment

... To fulfil this requirement, $y_\infty$ is set to the lowest value
of $y\left(\tau_\text{max}\right)$ and $-\max\left|y\right|$
multiplied by $1+\epsilon_\text{mach}$ \footnote{$\epsilon_\text{mach}$ is
the smallest number such that $\epsilon_\text{mach} + 1 > 1$. The
existence of such a number comes from the finite precision of the
computer}, if $y\left(\tau_\text{max}\right)<0$. Otherwise ...


How can I avoid the footnote digit appearing as an exponent. This sentence is packed with information so it is tricky to add this explanation.

• don't associate footnotes with matematical contents. It will simply confuse your readers. Rewrite the text and if you still feel the need then attach the footnote to some text instead. – daleif Jul 16 '15 at 13:02
• And please do not use _\text{mach}, it will come out wrong in an italic context (like inside a theorem). Use _{\textup{mach}} or _{\textnormal{mach}}. The fact that _\text{...} work without and extra set of {}'s is just a stroke of luck, should not be depended upon – daleif Jul 16 '15 at 13:14

Avoid footnotes to math material (and avoid footnotes in general).

In this case you should at least have the footnote marker after the comma, but it's just less confusing.

I'd reword the paragraph, taking also into account the fact that εmach is an important ingredient in the formula; footnotes should only contain material that can be skipped.

\documentclass{article}
\usepackage{amsmath}

\newcommand{\tsub}{_{\textnormal{#1}}}

\textheight=4cm % just not to waste space

\begin{document}

To fulfil this requirement, $y_\infty$ is set to the lowest value
of $y(\tau\tsub{max})$ and $-\max\lvert y\rvert$ multiplied by
$1+\epsilon\tsub{mach}$, if $y\left(\tau_\text{max}\right)<0$.
We denote by $\epsilon\tsub{mach}$ the smallest number such that
$\epsilon\tsub{mach} + 1 > 1$; its existence is ensured by the
finite precision of the computer. Otherwise ...

\bigskip

To fulfil this requirement, $y_\infty$ is set to the lowest value
of $y(\tau\tsub{max})$ and $-\max\lvert y\rvert$
multiplied by $1+\epsilon\tsub{mach}$,\footnote{$\epsilon\tsub{mach}$ is
the smallest number such that $\epsilon\tsub{mach} + 1 > 1$. The
existence of such a number comes from the finite precision of the
computer} if $y(\tau\tsub{max})<0$. Otherwise ...

\end{document} I removed the wrong \left\right pairs and defined a correct command for textual subscripts.

I suggest the following rewrite that does not need a footnote:

... multiplied by $1+\epsilon_\textnormal{mach}$ where $\epsilon_\textnormal{mach}$ is the smallest number such that $\epsilon_\textnormal{mach} + 1 > 1$.


I fully agree with daleif that footnote markers (whether they are numerical or letters or symbolics) are just confusing when applied to mathematical formulæ.

• I would, but the sentence continues with an "if", which is more important information. – user877329 Jul 16 '15 at 13:18
• @user877329 then place the comment in (...) – daleif Jul 16 '15 at 13:21

Here are two alternatives: The first uses a different symbol to indicate the footnote. The second re-words the sentences to eliminate a use of footnote.

\documentclass[12pt]{article}
\usepackage[symbol*]{footmisc}

\DefineFNsymbols*{lamport}{\dagger\ddagger\S\P\|%
{**}{\dagger\dagger}{\ddagger\ddagger}
}

\begin{document}

... To fulfil this requirement, $y_\infty$ is set to the lowest value
of $y\left(\tau_\text{max}\right)$ and $-\max\left|y\right|$
multiplied by $(1+\epsilon_\text{mach})$ \footnote{$\epsilon_\text{mach}$ is
the smallest number such that $\epsilon_\text{mach} + 1 > 1$. The
existence of such a number comes from the finite precision of the
computer}, if $y\left(\tau_\text{max}\right)<0$. Otherwise ...

\vspace{5mm}
... To fulfil this requirement, $y_\infty$ is set to the lowest value
of $y\left(\tau_\text{max}\right)$ and $-\max\left|y\right|$
multiplied by $(1+\epsilon_\text{mach})$ if $y\left(\tau_\text{max}\right)<0$.
Here $\epsilon_\text{mach}$ is the smallest number such that $\epsilon_\text{mach} + 1 > 1$. The
existence of such a number comes from the finite precision of the
computer. Otherwise ...

\end{document}


The footmisc documentation is obtained from http://texdoc.net/texmf-dist/doc/latex/footmisc/footmisc.pdf