How to type a non-breaking hyphen (dash, "-" character) in scientific or technical documents

Question

I am writing scientific or technical documents in LaTeX. Often I need to type a non-breaking space, for example when using equation references:

Equation~\eqref{eq:equation1example} shows blaa...

Is there a way of inserting non-breaking hyphens?

For example, this may be useful for technical terms such as Runge-Kutta, non-linear, non-converging or Van-der-Pol Oscillator which would not usually be split over lines.

Additionally, this may be desirable for citations and Author names, or publisher names.

Answer 1

If you use the amsmath package, you could employ its \nobreakdash macro to insert a dash or en-dash after which no line break is allowed.

Three examples (all from the user guide of the amsmath package):

$p$\nobreakdash-adic
$n$\nobreakdash-dimensional
pages 1\nobreakdash--9

Basically, where you'd normally write - ("dash") in the input file, you would now write \nobreakdash-, and where you'd normally write -- ("en-dash"), you would now write \nobreakdash--.

The joined-up expression $n$\nobreakdash-dimensional is quite long and might create bad line breaks. To keep this from happening, while still prohibiting a linebreak after $n$-, you could write

$n$\nobreakdash-\hspace{0pt}dimensional

That way, if need be, LaTeX can find a line break somewhere inside the "dimensional" substring. Presumably, you're OK with $n$-dimen- being at the end of one line and sional at start of the next line. If you have a lot of instances of "n-dimensional" in your document, it may make sense to set up a macro such as

\newcommand\ndim{$n$\nobreakdash-\hspace{0pt}dimensional}

in the preamble and to write \ndim{} everywhere in the body of the document.

Answer 2

With the babel package loaded there is \babelhyphen{nobreak} available (alongside \babelhyphen{soft}, \babelhyphen{hard} and a few others). While it prohibits a break after the dash the following word may still be hyphenated:

$n$\babelhyphen{nobreak}dimensional

The language ngerman (maybe others, too) defines a shorthand for a non-breaking hyphen: "~. With \addto\extrasenglish{\languageshorthands{ngerman}} it (and the other ngerman shorthands) can be added to english for example. (It probably must be activated with \useshorthands{"}. Contrary to \babelhyphen{nobreak} "~ does not allow the following word to be hyphenated.

% preamble
\usepackage[ngerman,english]{babel}
\addtoextrasenglish{\languageshorthands{ngerman}\useshorthands{"}}
...
% document
$n$"~dimensional

You can also define the shorthand yourself – either general

\defineshorthand{"~}{\babelhyphen{nobreak}}
\useshorthands{"}

or explicitly for one language (english as example):

\defineshorthand[english]{"~}{\babelhyphen{nobreak}}
\addto\extrasenglish{
  \languageshorthands{english}
  \useshorthands{"}
}

A complete example:

\documentclass{article}

\usepackage[ngerman,english]{babel}

\defineshorthand[english]{"~}{\babelhyphen{nobreak}}
\addto\extrasenglish{
  \languageshorthands{english}
  \useshorthands{"}
}

\begin{document}

% default:
\parbox{3em}{$n$-dimensional}

\bigskip
% \babelhyphen{nobreak}:
\parbox{3em}{$n$\babelhyphen{nobreak}dimensional}

\bigskip
% new `english' shorthand:
\parbox{3em}{$n$"~dimensional}

\bigskip\selectlanguage{ngerman}
% `ngerman' shorthand:
\parbox{3em}{$n$"~dimensional}

\end{document}

Answer 3

It is also possible to wrap part of text that should not be wrapped or only the dash in \mbox{…}:

\mbox{non-linear}
non\mbox{-}linear

Answer 4

The package extdash provides several options for typesetting hyphens and dashes, including disabling line-breaks after them by either:

1. adding an asterisk to the written-out command

something\Hyphdash* something
something\Endash* something

2. with the shortcuts option loaded, using equal signs instead of hyphens:

something\=/something
something\==/something

(examples from the package documentation)