# Resize integral symbol in the same way of a delimiter

This answer addresses the possible way to typeset a bigger integral sign, but one has to choose the right size of the symbol that better fits the situation.

My question is: why can't we resize the \int symbol as we usually do for common delimiters (), [] and \{\}?

By writing

\left\{ \left[ \left( stuff \right) \right] \right\}


delimiters are automatically sized with respect to stuff and the preceding/subsequent delimiter.

Why can't we write

\left \int \left\{ \left[ \left( stuff \right) \right] \right\} \right.


so that the \int symbol is automatically sized, too?

• most fonts only have the integral and summation in two sizes, they are not really delimiters that should stretch, but stylized S and Sigma characters – David Carlisle Mar 11 '20 at 17:26
• Indeed, they are not delimiters. But from a practical point of view, they are treated almost likewise, at least from an aesthetical point of view (maybe). – Alessandro Cuttin Mar 11 '20 at 17:34
• well not really \sum can't scale at all and \int you could only scale if it has a vertical style , actually I think there is at least one tex font package that does scale int but I'm out of time now, may look later if no one has answered – David Carlisle Mar 11 '20 at 17:41
• @AlessandroCuttin Please, don't. Four story or bigger fractions are evil and should be avoided like the plague. – egreg Mar 11 '20 at 18:02
• Have you seen the posting Big integral sign? – Mico Mar 11 '20 at 20:30

Opentype Math fonts can make use of the Integral extension character U+23AE

I'm not sure I like the result but this is Cambria Math with LuaLaTeX.

\documentclass{article}
\usepackage{unicode-math}
\setmathfont{Cambria math}

\begin{document}

$\Uleft\Udelimiter 0 0 "222B \begin{pmatrix} 1 \end{pmatrix} \Uright. \rightarrow \Uleft\Udelimiter 0 0 "222B \begin{pmatrix} 1\\2 \end{pmatrix} \Uright. \rightarrow \Uleft\Udelimiter 0 0 "222B \begin{pmatrix} 1\\2\\3\\4 \end{pmatrix} \Uright. \rightarrow \Uleft\Udelimiter 0 0 "222B \begin{pmatrix} 1\\2\\3\\4\\5\\6 \end{pmatrix} \Uright.$
\end{document}

• I'm not sure that you can put limits on these extended integrals though. – David Carlisle Mar 11 '20 at 22:50