Vectors have units, if you leave them off you are probably a mathematician (just kidding). Also, this notation can be expanded to three dimensions by adding a z-hat or k-hat component.

Combining Vectors Graphically: Students learn to combine component vectors graphically to produce resultants and use the head-to-tail method to do a vector analysis of a route between rooms.

The elements of each latent vector are the coefficients of a principal component (with sum of squares of coefficients being unity). The object of the paper is to obtain the exact distribution of the ...