Orthonormal Basis

A Basis of Vectors ${\bf x}$ which satisfy

$$x_j\cdot x_k = \delta_{jk}$$

or, in Tensor notation,

$$x^\mu x_\nu = \delta_\nu^\mu,$$

where $\delta_{jk}$ is the Kronecker Delta. An orthonormal basis is a normalized Orthogonal Basis.

See also Basis, Orthogonal Basis