How to reduce spacing in equations?

I want to typeset short equations (variable = value) saving space.

Is there a global parameter which allows to reduce the space between operators and operands in math mode?

I found out, that there is a negative space \!which could be used, but I would have to type it in each single equation, which is inefficient.

\documentclass[11pt, a4paper]{scrbook}
\usepackage[ngerman]{babel}
\begin{document}
$a_0\!\!=\!\!12{,}459$

\end{document}
• Not only is using \! inefficient: you shouldn't use it around binary operations or relations since it can lead to very bad spacing; see e.g. this answer. – Hendrik Vogt Jun 25 '12 at 7:57

$a_0{=}12{,}459$

\thickmuskip=0.5\thickmuskip
$a_0=12{,}459$

\thickmuskip=0mu
$a_0=12{,}459$

from Typographer's view: it is not a good idea ...

• thanks! I agree that the standard spacing makes sense, but I have to deal with a large matrix of graphs where lateral space is a serious problem. I do want to use that only in those graphs. However, your solution is more elegant then \!\!= but also "local" and no global option. And maybe there could be a compromise which half of the standard space (as a global option)? – MostlyHarmless Nov 30 '11 at 11:06
• @Martin: you can decrease \thickmuskip for a global setting, see edited answer – user2478 Nov 30 '11 at 11:10

If all of your math is of this form then you can think of reducing the space; but it's not a good idea, in my opinion.

I suggest a different approach than redefining globally the spacing around relation symbols:

\newcommand{\seq}{\,{=}\,} % special equals

so that, if you change your mind, it's just a matter of changing this into

\newcommand{\seq}{=}