[LaTeX] Delimiters
category: Writing  course: LaTeX Math  difficulty:Lots of mathematical formulas have their components grouped, or have a useful shorthand notation that requires a part to be enclosed within socalled delimiters. The regular symbols, such as parentheses ( ()
) and braces ( {}
) work, but don’t scale with the equation – a fraction, for example, is much taller than the symbols surrounding it, which looks ugly and messy.
To solve this, LaTeX provides the \left
and \right
commands. These need to be used together, always, and both need a certain delimiter right after it. In between them, you are allowed to use as many \middle
commands with delimiters as you like. The possibilities are:
Left 
Right 
Description 
Common Use 


Regular parentheses 
Grouping equations 


Regular brackets 
Alternative to grouping equations 


Regular braces 
Denoting sets 


Arrows 
Intervals or dot products 


Vertical lines 
Determinant or absolute value 


Double vertical lines 
Norm 


Empty delimiter 
Displays nothing 


Box with open top and gap in bottom side 
Rounding a number down 


Box with open bottom and gap in top side 
Rounding a number up 


Smaller version of the previous command 
Rounding a number 
\begin{equation*} \left( \frac{2}{3} \right) \end{equation*} \begin{equation*} \left x+y \right \end{equation*} \begin{equation*} \left\{ x \in \mathbb{R}^3 \middle x \not= 2 \right\} \end{equation*}
Custom Sizes
If you’re not satisfied with LaTeX stretching your delimiters to the correct length automatically, you can use the special symbolsizing commands:
Command 
Description 

Slightly bigger than normal 

Even bigger 

Even bigger 

Biggest 
These also work for most other symbols, which you’ll learn in a later chapter. Note that these should be used instead of the \left
and \right
commands.
\begin{equation*} %Yes, this looks awful, it's just for demonstrative purposes \Bigg( \frac{2}{3} \big) \end{equation*}