# Punctuation spacing after long exponents

When typesetting equations with long exponents or high-numbered footnotes right before punctuation marks, the result is a rather awkward large space between the last letter and the punctuation mark:

\setcounter{footnote}{138}
{\Huge
$X^{\mathrm{red}}$, blah\footnote{}.
}


resulting in

Now, I'm not sure that this would actually look better, but is there an (elegant, i.e. no manually inserted negative whitespace ....) way to have the . and , appear under the exponent?

EDIT: To avoid confusion: I'm interested to find out whether it's possible to have the , in $X^{\mathrm{red}}$, treated like the 0 in $X_{0}^{\mathrm{red}}$. Whether this behaviour is advisable is, of course, an entirely different question!

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+1 An interesting question, but I don't know if anyone would ever recommend doing this. You would be asking the reader to parse the exponent (or footnote) at the same time as the punctuation, which would be confusing. The way it stands in your MWE, the reader parses the two things separately, which is much more digestible. Still, an interesting question nonetheless :) – cmhughes Dec 12 '12 at 16:57
I pretty much concur with @cmhughes. There are times, though, when I'm bothered by the punctuation as the end of a mathematical expression. I don't have issues with the commas internal to the expression. But I and my students can be distracted by an apparently dangling comma or period. To get around this annoyance, I usual find another way to rewrite what I wrote in order to avoid a sentence ending with the mathematical expression capped by punctuation. Probably not the answer you're looking for---hence I've only put it in a comment. – A.Ellett Dec 12 '12 at 18:32

The space is only apparent:

\documentclass[12pt]{article}

\newcommand{\tryrule}{\leavevmode\smash{\kern-.2pt\vrule height\ht\strutbox\kern-.2pt}}

\begin{document}
\setcounter{footnote}{137}
$X^\mathrm{red}$\tryrule, blah\footnote{xyz}\tryrule, blah\tryrule,

$X^\mathrm{red}$, blah\footnote{xyz}, blah,

$X{\hskip\scriptspace\scriptstyle\mathrm{red}}$, blah{\hskip\scriptspace\scriptsize139}, blah,
\end{document}


In the first line the rule is just to show precisely the division between the characters (it takes up no space, as shown by the second line). In the third line the objects are shifted to the baseline.

You may want to insert a negative thin space:

$X^\mathrm{red}$\negthinspace, blah\footnote{xyz}\negthinspace, blah,


The remark cgnieder made in a comment is very worth noting! The fnpct package allows for very fine control about the footnote mark placement, with its

\setfnpct


command.

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I think there might have been some misunderstanding ... I wanted the punctuation mark underneath the exponent, i.e. directly after X or h, under r and 1, respectively. In other words, I'm looking for similar behaviour as $X^{235}_{0}$ only with my punctuation mark where the 0 is. As @cmhughes pointed out above, this might be even more confusing than a big space but I thought trying it out coldn't hurt (too much :)). – Jonathan Dec 12 '12 at 18:18
@Jonathan The comma underneath an exponent in a math formula would be definitely wrong. Somebody uses footnote marks after punctuation, rather than above it. Say \rlap{,}\footnote{text} to get the footnote mark above the comma. – egreg Dec 12 '12 at 18:48
@Jonathan while the comma really shouldn't be placed underneath an exponent the fnpct package gives you means to control the interaction of footnote marks and punctuation – clemens Dec 14 '12 at 19:28