A matrix is a rectangular array of numbers. The numbers may be real or complex. We represent it as
where aij represents the element at the intersection of ith row and jth column.
In case the order of a matrix is established or known then we shall simply write
A = [aij] of type m×n
A matrix with m rows and n columns is called m _ n matrix and dimension (or size) of this matrix is said to be m _ n.