A two-dimensional array. In computing, matrices are usually considered
to be special cases of n-dimensional arrays, expressed as arrays with two
indices. The notation for arrays is determined by the programming language. The
two dimensions of a matrix are known as its rows and columns; a matrix with m
rows and n columns is said to be an m x n matrix. In mathematics the conventional notation is to use a capital letter to denote a
matrix in its entirety, and the corresponding lower-case letter,
indexed by a pair of subscripts, to denote an element in the matrix.
Thus the i,jth element
of a matrix A is denoted by aij, where i is the row number and j the column
A deficient two-dimensional array, in which one of the dimensions has only one
index value (and is consequently elided) is a special kind of matrix known
either as a row vector (with the column elided) or column vector (with the row
elided). The distinction between row and column shows that the two dimensions
are still significant.