## APPENDIXE

Row matrices and column matrices are especially useful in describing vectors, since the elements of the rows or columns can be taken to be the components of the vectors. It is most important, however, to distinguish between matrices and vectors. While vectors can, for convenience, be written in a matrix form, either row or column, the matrix must not be identified as the vector itself, since a matrix is only an array of numbers, while a vector usually carries some physical

It has m rows and n columns, and is usually described as an matrix. The Droduct is called the dimension of the matrix, and it is called a square matrix,

The indices i and j indicate the location of the element in the ith row and 7 th column of the arrav. The matrix itself is often given as

Other matrices, those such as B and C, would andcustomarily be written

If a matrix has only one row, then it is usually called a row matrix, as with , and if it has but a single column, it is named a column matrix,

dimensions as well. Moreover, not all matrices are vectors by any means, as the constitutive formulas, incidence matrices, continuity laws, in Chapter 3, and the link-node incidence matrices in Chapter 6 illustrate.