Enlarge the integral sign proportional to its content

Question

In LaTeX you have a command like \left(\right) to enlarge the brackets proportional to the content between the brackets.

for instance \left(a\right) will produce smaller brackets than \left(\displaystyle\frac{a}{b^n}\right)

Is there a similar trick for the integral sign?

Perhaps related: How can I have a bigger integral (\int) delimiter? — Werner, May 28 '12 at 20:26
@egreg: MS Office does that (if the OpenType math font supports it) and some people seem to think it makes it better than TeX... — خالد حسني, May 28 '12 at 20:28
@egreg: It's not my idea (I'm asking this for someone I know :D). And perhaps this is indeed awful however one does expect LaTeX to have a general solution to this probem (so one can do this trick with other symbols) — willeM_ Van Onsem, May 28 '12 at 20:29
@Werner: true but then the author needs to take care of the size of the integral sign himself. What for instance if the content depends on some external commands he will fill in later. — willeM_ Van Onsem, May 28 '12 at 20:30
@CommuSoft Stacking fractions is never a good way to present math. Enlarging an integral sign for covering a matrix is something I can't even think to. Looking at the documentation of bigints requires me to get my copy of Tschichold from the shelf. — egreg, May 28 '12 at 20:31
I agree there are some arguments against the idea. However I am wondering if there is a general solution to the problem. For instance what if someone makes his own backets? — willeM_ Van Onsem, May 28 '12 at 20:38
I haven't tried it myself, and I currently have no (trustable) LaTeX compiler at hand, but have you tried something like $\left\int [big stuff...] dx \right.$.? — Tomas Aschan, May 28 '12 at 20:41
@TomasLycken Not compilable. \int doesnt expand in that manner or behave in that manner. — azetina, May 28 '12 at 20:45

score 5 · Accepted Answer · answered May 28 '12 at 21:42

A hacky solution using unicode-math that only works with fonts that have multiple integral sizes (e,g. Asana Math or Cambria Math), and xelatex or lualatex of course:

\documentclass{article}
\usepackage{unicode-math}
\setmathfont{Asana Math}

\def\delint{\Udelimiter 4 \symoperators "222B }
\def\extint#1{\left\delint #1\right.}
\begin{document}
\[
\extint{\frac{\sum^{a+b}}{\sum_{x+y}}} \int
\]
\end{document}

enter image description here

Integral indices are broken, though (needs more thought).

Enlarge the integral sign proportional to its content

1 Answers1