| vector rot U associated at each point of a given space region with a vector U, equal to the limit of the integral over a closed surface S of the vector product of the vector surface element and the vector U, divided by the volume of the interior of the surface, when the surface is contained in a sphere the radius of which tends to zero|
where endA is the vector surface element oriented outwards and V is the volume
Note 1 to entry: In orthonormal Cartesian coordinates, the three coordinates of the rotation are:
Note 2 to entry: The rotation of a polar vector is an axial vector and the rotation of an axial vector is a polar vector.
Note 3 to entry: The rotation of the vector field U is denoted by or . In some English texts, the rotation is denoted by .