Definition:Floor Function/Notation

Definition
The older and more usual symbol for the floor function is $\left[{x}\right]$, but there are already enough uses to which square brackets are put.

The notation $\left \lfloor {x} \right \rfloor$ for the floor function is a relatively recent development.

Compare the notation for the corresponding ceiling function, $\left\lceil{x}\right\rceil$, which in the context of discrete mathematics is used almost as much.