\bigl, \bigr, etc. ¶Synopsis, one of:
\bigldelimiter1 ... \bigrdelimiter2 \Bigldelimiter1 ... \bigrdelimiter2 \biggldelimiter1 ... \biggrdelimiter2 \Biggldelimiter1 ... \Biggrdelimiter2
(as with \bigl[...\bigr]; strictly speaking they need not be
paired, see below), or one of:
\bigmdelimiter \Bigmdelimiter \biggmdelimiter \Biggmdelimiter
(as with \bigm|), or one of:
\bigdelimiter \Bigdelimiter \biggdelimiter \Biggdelimiter
(as with \big[).
Produce manually-sized delimiters. For delimiters that are
automatically sized see \left & \right).
This produces slightly larger outer vertical bars.
\bigl| |x|+|y| \bigr|
The commands above are listed in order of increasing size. You can use
the smallest size such as \bigl...\bigr in a paragraph without
causing LaTeX to spread the lines apart. The larger sizes are meant
for displayed equations.
See Delimiters, for a list of the common delimiters. In the family of commands with ‘l’ or ‘r’, delimiter1 and delimiter2 need not match together.
The ‘l’ and ‘r’ commands produce open and close delimiters that insert no horizontal space between a preceding atom and the delimiter, while the commands without ‘l’ and ‘r’ insert some space (because each delimiter is set as an ordinary variable). Compare these two.
\begin{tabular}{l}
\(\displaystyle \sin\biggl(\frac{1}{2}\biggr) \) \\ % good
\(\displaystyle \sin\bigg(\frac{1}{2}\bigg) \) \\ % bad
\end{tabular}
The traditional typographic treatment is on the first line. On the
second line the output will have some extra space between the
\sin and the open parenthesis.
Commands without ‘l’ or ‘r’ do give correct spacing in some circumstances, as with this large vertical line
\begin{equation}
\int_{x=a}^b x^2\,dx = \frac{1}{3} x^3 \Big|_{x=a}^b
\end{equation}
(many authors would replace \frac with the \tfrac command
from the amsmath package), and as with this larger slash.
\begin{equation}
\lim_{n\to\infty}\pi(n) \big/ (n/\log n) = 1
\end{equation}
Unlike the \left...\right pair (see \left & \right), the
commands here with ‘l’ or ‘r’ do not make a group.
Strictly speaking they need not be matched so you can write something
like this.
\begin{equation}
\Biggl[ \pi/6 ]
\end{equation}
The commands with ‘m’ are for relations, which are in the middle of formulas, as here.
\begin{equation}
\biggl\{ a\in B \biggm| a=\sum_{0\leq i<n}3i^2+4 \biggr\}
\end{equation}