space. A vector which gains a minus sign when the orientation of space changes is called a pseudovector or an axial vector. Ordinary vectors are sometimes called true vectors or polar vectors to distinguish them from pseudovectors. Pseudovectors occur most frequently as the cross product of two ordinary vectors. One example of a pseudovector is angular velocity. Driving in a car, and looking forward, each of the wheels has an angular velocity vector pointing to the left. If the world is reflected in a mirror which switches the left and right side of the car, the reflection of this angular velocity vector points to the right, but the angular velocity vector of the wheel still points to the left, corresponding to the minus sign. Other examples of pseudovectors include magnetic field, torque, or more generally any cross product of two (true) vectors. This distinction between vectors and pseudovectors is often ignored, but it becomes important in studying symmetry properties. See parity (physics). See also Affine space, which distinguishes between vectors and points Array (data structure) Banach space Clifford algebra Complex number Coordinate system Covariance and contravariance of vectors Four-vector, a non-Euclidean vector in Minkowski space (i.e. four-dimensional spacetime), important in relativity Function space Grassmann's Ausdehnungslehre Hilbert space Normal vector Null vector Position (geometry) Pseudovector Quaternion Tangential and normal components (of a vector) Tensor Unit vector Vector bundle Vector calculus Vector notation Vector-valued function Notes References Mathematical treatments . . . . Physical treatments External links Online vector identities (PDF) Introducing Vectors A conceptual introduction (applied mathematics) Kinematics Abstract algebra Vector calculus Linear algebra Concepts in physics Vectors (mathematics and physics) Analytic geometry Euclidean geometry