A square matrix has as many rows as it has columns. Matrix A is square but matrix B is not square: A = 1 6 3 2 , B = 1 9 0 3 7 −2 A symmetric matrix is a square matrix in which x ij = x ji for all i and j. Matrix A is symmetric; matrix B is not symmetri

one dimensional matrices (ie: 1 ×m or n ×1 matrices). One dimensional matrices are often called vectors, as in row vector for a n ×1 matrix or column vector for a 1 ×m matrix but we are going to use the word “vector” to refer to something differe

A diagonal matrix is a square matrix with entries only along the diagonal, with all others being zero. A diagonal matrix whose diagonal entries are all 1 is called an identity matrix. The identity matrix is denoted I n, or simply I. The zero matrix O m×n