Delimiters

these	are made by these	and these	are made by these
(	(	)	)
[	[	]	]
$\{$	\{	$\}$	\}
$\lfloor$	\lfloor	$\rfloor$	\rfloor
$\lceil$	\lceil	$\rceil$	\rceil
$\langle$	\langle	$\rangle$	\rangle
/	/	$\backslash$	\backslash
|	|	$\Vert$	\|
$\uparrow$	\uparrow	$\Uparrow$	\Uparrow
$\downarrow$	\downarrow	$\Downarrow$	\Downarrow
$\updownarrow$	\updownarrow	$\Updownarrow$	\Updownarrow

This table shows the standard sizes. To get bigger sizes, use these prefices

(for left delimiters)	(for right delimiters)	magnification
\bigl	\bigr	a bit bigger, but won't overlap lines
\Bigl	\Bigr	150% times big
\biggl	\biggr	200% times big
\Biggl	\Biggr	250% times big

For example,

$\Biggl\{2\Bigl(x(3+y)\Bigr)\Biggr\}$

gives $\Biggl\{2\Bigl(x(3+y)\Bigr)\Biggr\}$. If you're not using the default text size these commands might not work correctly. In that case try the exscale package.

It's preferable to let L^ATEX choose the delimiter size for you by using \left and \right. These will produce delimiters just big enough for the formulae inbetween.

$\left( \frac{(x+iy)}{\{\int x\}} \right)$

gives $\left( (x+iy) \over \{\int x\} \right)$

The left and right delimiters needn't be the same type. It's sometimes useful to make one of them invisible

\[ z = \left\{
              \begin{array}{ll}
                   1 & (x>0)\\
                   0 & (x<0)
              \end{array}
       \right. 
\]

produces

$$z = \left\{ \begin{array}{ll} 1 & (x>0)\\ 0 & (x<0) \end{array} \right.$$

Over- and underbracing works too.

$\overbrace{\alpha \ldots \omega}^{\mbox{greek}} 
 \underbrace{a \ldots z}_{\mbox{english}}$

produces $\overbrace{\alpha \ldots \omega}^{\mbox{greek}} \underbrace{a \ldots z}_{\mbox {english}}$. The use of \mbox stops the text appearing in math italic.