A Cartesian plane in which the two axes of the vector space are perpendicular.

### Examples

\(\overrightarrow{v}\perp \overrightarrow{u}\) and \(m\left ( \overrightarrow{v} \right )\neq m\left ( \overrightarrow{u} \right )\)

In this case, the vector space can also be normed; if so, it is said to be orthonormal, as in the following example:

\(\overrightarrow{j} \perp \overrightarrow{i}\) and m(\(\overrightarrow{j}\)) = m(\(\overrightarrow{i}\))