# Even and Odd Functions

### Even Function - Symmetry about the Vertical Axis

A function, **f**, is symmetrical about the vertical axis when all the values of x in the domain are verified:

**f(−x) = f(x) **

The functions that are symmetrical about the vertical axis are called **even functions**.

### Odd Function - Symmetry about the Origin

A function, f, is symmetrical about the origin if all values of x in the domain are verified:

**f(−x) = −f(x) **

The symmetrical functions about the origin are called **odd functions**.