[Tex/LaTex] Text mode commands/symbols in math mode

equationsmath-modesymbols

I am fairly new to LaTeX, and have run into a problem with commands apparently only available in text mode, where I would like to use them in math mode as well (e.g. integrated in equations).

One of the commands/symbols in question is the upside down exclamation sign used to represent the subfactorial function.
In running text, I can use the command \textexclamdown, but this does not work in math mode (as far as I can tell).

Is there a way to seamlessly integrate text mode commands in the middle of rather hairy equations?

Best Answer

You can define your own symbol:

\documentclass{article}
\usepackage{amsmath}

\DeclareMathSymbol{\subfactorial}{\mathord}{operators}{"3C}

\begin{document}
\begin{equation}
\begin{aligned}
n!=\sum_k h(n,k) &= \sum_k \binom{n}{k}(n-k)\subfactorial\\
  &=\sum_k\binom{n}{k}k\subfactorial
\end{aligned}
\tag{5.49}
\end{equation}
\end{document}

This will work so long as the "operators" font is OT1 encoded. Should it be T1 encoded, change "3C" into "BD (this might depend on your font settings).

The equation (same number) is taken from "Discrete Mathematics", by Graham, Knuth and Patashnik (the original uses Euler fonts, but the result is quite similar).

enter image description here

Related Solutions

[Tex/LaTex] Why do the less than symbol (<) and the greater than symbol (>) appear wrong as upside down exclamation (¡) or question mark (¿)

Geoffs tip with \textless and \textgreater will work well for you. However, you could type these symbols < and > directly in your editor and they would be correctly printed if you use the recommended font encoding, Cork resp. T1:

\usepackage[T1]{fontenc}

Have a look at the T1 encoding table, search for the symbols < and >. Afterwards, open the OT1 encoding table, which is the default. At the two corresponding places you will find the upside down exclamation resp. quotation mark. That should explain it.

For further reasons, why you should use T1 encoding, have a look at this question: Why should I use \usepackage[T1]{fontenc}?

You should use a font supporting T1. For instance use the very good Latin Modern font, derived from the standard fonts:

\usepackage{lmodern}

Or install the cm-super package which provides the standard Computer Modern fonts with T1 support.

[Tex/LaTex] Reduce Spacing In $$

If it's important to keep the same shape of > then make sure you're using the amsmath package because it gives you three types of negative space: thin, medium and thick. Per your question, negative spacing is the method to reduce spacing. This code shows your options:

\documentclass{article}
\usepackage{amsmath}
\begin{document}
$<x>$\\
$\langle x \rangle$   \\
$< \, x \,>$\\
$< \negmedspace x \negmedspace >$\\
$< \negthickspace x \negthickspace >$\\
\end{document}

Personally, I like Jeff's solution or the solution with negmedspace.

Best Answer

Related Solutions

[Tex/LaTex] Why do the less than symbol (<) and the greater than symbol (>) appear wrong as upside down exclamation (¡) or question mark (¿)

[Tex/LaTex] Reduce Spacing In $$

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