A matrix A is a rectangular array of numbers
If there are m rows and
n columns, we say that the dimension
of the matrix is m x n,
and we refer to it as an "m by n matrix", or as a
rectangular matrix. An n x n matrix is called a square matrix
and is said to be of order n.
An m x n matrix A is often abbreviated as
A=(aij)m x n.
The entry, or element, in the ith row and
jth column of an m x n matrix A
is denoted aij.
The entries
a11, a22, a33,...
in a square matrix are said to be on the
main diagonal of the matrix. |