# Symbol distance of double, triple, etc. integrals of CM

Just a curiosity:

why in Computer Modern (and I think in other some fonts) the double integral signs have a high distance of default?

\documentclass[12pt]{article}
\usepackage{amsmath}
\usepackage{amssymb}

\begin{document}
$\iint_D f(x,y)\, dxdy$
\end{document}


With amsmath, the multiple integral signs are spaced using \intkern@, whose definition is

% amsmath.sty, line 654:
\def\intkern@{\mkern-6mu\mathchoice{\mkern-3mu}{}{}{}}


which means that there is a negative kern of 6mu, which is increased to 9mu in display style.

You can modify this default. Here's an example, but of course the redefinition should go in the preamble.

\documentclass[12pt]{article}
\usepackage{amsmath}

\begin{document}

\begin{center}
$\iint_D f(x,y)\,dx\,dy$
\end{center}
$\iint_D f(x,y)\, dx\,dy$
\makeatletter
\def\intkern@{\mkern-9mu\mathchoice{\mkern-4mu}{}{}{}}
\makeatother
\begin{center}
$\iint_D f(x,y)\,dx\,dy$
\end{center}
$\iint_D f(x,y)\, dx\,dy$
\end{document}


• Thank you immensely, immensely like the title of a song by Umberto Tozzi my favorite singer. Now I ask myself? But isn't the spacing \def\intkern@{\mkern-9mu\mathchoice{\mkern-4mu}{} better? Sep 25 at 22:44
• @Sebastiano It’s a question of personal preferences Sep 26 at 7:18
• I remember (but may be wrong), that the amsmath package has been updated recently. Many years ago I didn't remember that the two integral symbols had this large distance. Sep 26 at 19:11
• @Sebastiano Version 2.13, released 2000/07/18, has the same values. Sep 26 at 19:50