Examples are velocity and force .
Another way of representing a vector is by indicial notation. If we let the subscript i denote any one of three symbols x, y, z then represents symbolically a vector since is merely an abbreviation for the set of symbols , these being the scalar components of the vector. The indicial notation is most useful in dealing with tensors. Thus, would represent a tensor in the sense that it implies nine different permutations of the subscripts x, y, z, taken two at a time. In using indicial notation, the convenction is adopted that when more than one of the same subscript is present in a given quantity, this indicates that the quantity is to be summed over all values of that subscript.