Guide to LaTeX (4th Edition) (Tools and Techniques

132 Chapter 5. Mathematical Formulas
x=1 +
x=0
\[ \left[ \int + \int \right]_{x=0}ˆ{x=1} \]
The pair of brackets [ ] is adjusted to the size of the enclosed
formula, as are the raised exponent and lowered
index as well.
The commands \left and \right must appear as a pair. For every
\left command there must be a corresponding \right command somewhere
afterwards. The pairs may be nested. The first \left is paired with
the last \right; the following \left with the second last \right, and so
on. There must be the same number of \right as \left commands in a
nesting.
The corresponding bracket symbols lbrack and rbrack may be perfectly
arbitrary and do not need to be a logical pair.
x + y + z =
a
b
This set of brackets is admittedly unusual but
permissible.
\[ \vec{x} + \vec{y} + \vec{z} =
\left( ... \right[ \]
Sometimes a formula contains only a single opening or closing bracket
without a corresponding counterpart. However, the \left. . . \right
commands must still be given as a pair, but with a period ‘.’ as an invisible
bracket symbol.
⎧
⎪⎨ −1 : x < 0
y =
⎪⎩
0
+1
:
:
x = 0
x > 0
\[ y = \left\{ \begin{array}
{r@{\quad:\quad}l}
-1 & x0
\end{array} \right. \]
The array environment in the above example is described in Section 4.8.1
and produces a table in math mode.
The \left. . . \right commands may be applied to a total of 22 different
symbols. These are
( ( ) ) ⌊ \lfloor ⌋ \rfloor
[ [ ] ] ⌈ \lceil ⌉ \rceil
{ \{ } \} 〈 \langle 〉 \rangle
| | \| ↑ \uparrow ⇑ \Uparrow
/ / \ \backslash ↓
\downarrow
\updownarrow
⇓
\Downarrow
\Updownarrow
For example, \left|. . . \right| produces two vertical bars adjusted in
height to contain the enclosed formula text.
π
Exercise 5.12: In Equation 5.3, generate cos
2 z2
π
and sin
2 z2
instead of
cos( π
2 z2 ) and sin( π
2 z2 ).