# big angle brackets

I know that \langle and \rangle creates left and right angle brackets. But they don't seem to adopt to the size of the expression inside. For example, if I have a big matrix, I would like to angle brackets to be big as well. How can I get this effect?

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You can place \left and \right before each of them, respectively. –  OSE Apr 14 '13 at 23:48
as for all delimiters in TeX use \left\langle...\right\rangle They have a maximum size though they do not get arbitrarily big. –  David Carlisle Apr 14 '13 at 23:49
@user2018790: No, XBL has a BIG matrix. –  Przemysław Scherwentke Apr 14 '13 at 23:50
\left< and \right> are abbreviations for \left\langle and \right\rangle, respectively. –  Ari Brodsky Apr 15 '13 at 0:32
@AriBrodsky the point is that \left\right doesn't make delimiters big enough in this case, so \left< has same problem. –  David Carlisle Apr 15 '13 at 0:36

The mtpro2 package (MathTime Professional II) provides extra-large (up to 10 cm tall) fence symbols -- round parentheses, square brackets, curly braces, angle brackets, etc. -- via its \LEFTRIGHT command. Note that the full mtpro2 package isn't free of charge; however, its "lite" subset, which is all that's needed to produce extra-large fence symbols, is free of charge.

\documentclass{article}
\usepackage[lite]{mtpro2}
\begin{document}
$\LEFTRIGHT\langle\rangle{ \begin{array}{c} 1\\2\\3\\4\\5\\6\\7\\8\\9\\10 \end{array}}$
\end{document}

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Usual comment about perennial enmity between the copy editor and the creator of such a horror. ;-) –  egreg Apr 15 '13 at 9:19

In the standard fonts \langle has a fixed upper limit and doesn't grow above a certain size. (TeX extends characters by adding vertical extension glyphs and angle brackets don't have a vertical section that can be extended). However if you don't mind distorting the shape you can scale the bracket to fit:

\documentclass{article}
\usepackage{amsmath}
\usepackage{graphicx}
\begin{document}

$\left\langle\begin{array}{c}1\\2\\3\\4\\5\\6\end{array}\right\rangle$

$\sbox0{\begin{array}{c}1\\2\\3\\4\\5\\6\end{array}} \mathopen{\resizebox{1.2\width}{\ht0}{\Bigg\langle}} \usebox{0} \mathclose{\resizebox{1.2\width}{\ht0}{\Bigg\rangle}}$

\end{document}

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The stretched angle brackets currently don't seem to be quite tall enough to "cover" the lower part of the bottom row. Is there an adjustment to achieve this coverage? –  Mico Apr 15 '13 at 10:27
@Mico you can change \ht0 to 1.1\ht0 or whatever factor you like You can also fiddle with \raisebox{...}{\usebox{0}} to adjust the position of the box within the delimiters (the more you scale the more the difference between centering on the baseline and centering on the math axis is apparent) –  David Carlisle Apr 15 '13 at 11:24

This is the sort of thing the scalerel package was designed for. WIth the use of the width-limited \scaleleftright or aspect-limited \stretchleftright, a desirable outcome can often be achieved. In the below example, I show both, first employing \scaleleftright with a width limit of 1.75ex, and then showing \stretchleftright with an aspect limit of 1000% (i.e. stretch of 10). Note that in all cases, the symbols being manipulated are the humble < and > symbols, not some predefined stretchable version.

Finally, in the third figure set, I show that one can use a stretched version of \langle and \rangle, instead of < and >. Depending on the tastes of the user, one may be preferable to the other.

\documentclass{article}
\usepackage{scalerel}
\begin{document}

\setlength\arraycolsep{0ex}
$$\scaleleftright{<} {x} {>} % \scaleleftright[1.75ex]{<} {\begin{array}{c}x\\y\\z \end{array}} {>} % \scaleleftright[1.75ex]{<} {\begin{array}{c}u\\v\\w\\x\\y\\z \end{array}} {>} % \scaleleftright[1.75ex]{<} {\begin{array}{c}r\\s\\t\\u\\v\\w\\x\\y\\z \end{array}} {>}$$

$$\stretchleftright{<} {x} {>} % \stretchleftright[1000]{<} {\begin{array}{c}x\\y\\z \end{array}} {>} % \stretchleftright[1000]{<} {\begin{array}{c}u\\v\\w\\x\\y\\z \end{array}} {>} % \stretchleftright[1000]{<} {\begin{array}{c}r\\s\\t\\u\\v\\w\\x\\y\\z \end{array}} {>}$$

$$\stretchleftright{\langle} {x} {\rangle} % \stretchleftright[1000]{\langle} {\begin{array}{c}x\\y\\z \end{array}} {\rangle} % \stretchleftright[1000]{\langle} {\begin{array}{c}u\\v\\w\\x\\y\\z \end{array}} {\rangle} % \stretchleftright[1000]{\langle} {\begin{array}{c}r\\s\\t\\u\\v\\w\\x\\y\\z \end{array}} {\rangle}$$

\end{document}


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