ABSTRACT
This appendix reviews some basic aspects of matrix algebra, confining itself to those used in this book and proceeding largely by example rather than by formal definition and proof.
Matrices
A matrix is a rectangular array of numbers. Examples of three matrices, A, B, and D, are given in Fig. A.1. Matrix A has dimensions 4× 3 (the number of rows precedes the number of columns). B and D are square 3× 3 matrices; they can alternatively be described as being of order 3. Matrices B and D are also symmetric matrices: each row of the matrix is identical with the corresponding column, so that the matrix is symmetrical around the principal diagonal that runs from its upper left to lower right. A symmetric matrix is necessarily square, but a square matrix is not necessarily symmetric: The first three rows of matrix A would constitute a square, non-symmetric matrix.
