Matrix algebra is a handy way to do arithmetic for graphics. you can express the coordinates of a point as a column matrix shown below, or as a row matrix. The lines on either side of the letters indicate that we are talking about a matrix. Both of these matrices show the same information (in homogeneous coordinates). The difference between a row and a column form of a matrix becomes clear when you have to multiply matrices together. The individual numbers in a matrix are called its elements. For example x , y, z and 1 are all elements of the matrices below. Matrixes are stored as arrays in a program, and loops are the means for carrying out the matrix multiplications that are described here.