created 08/19/97; revised 08/06/00; 09/14/00; 07/20/03

Here are some of the terms we have been using:

**point**— a geometric object; a location in 3D (or 2D) space.**vector**— a geometric object that has properties of direction and length, but not location.**column matrix**— an ordered list of numbers arranged into a column.**row matrix**— an ordered list of numbers arranged into a row.**element**— one of the numbers that makes up a column or row matrix.**dimension**— the number of elements in a column or row matrix.**displacement**— the difference between two locations, expressed as a vector.

This chapter discusses addition and subtraction of column and row matrices.