Zero-dimensional: Span of the empty set: The origin
A point (x, y) can be represented in the plane by a {'x','y'}-vector<math>\begin{bmatrix} x \\ y \end{bmatrix}</math> .
A point can also be represented by {'x','y','z'}-vector<math>\begin{bmatrix} x \\ y \\ z\end{bmatrix}</math> . This representation is called homogeneous coordinates