A rectangular array of numbers, in which not only the value of the number is important but also its position in the array.

The numbers in the array are called _____________ of the matrix.

The size of the matrix is described by the number of its ____________________.

The elements (or the entries) of a matrix are generally enclosed in brack-

ets, double-subscripting is used to index the elements. The First subscript

always denote the ________ position.

The main diagonal in a square matrix contains the elements _______________

A matrix is said to be ________________ if all its entries below the main

diagonal are 0.

A matrix is said to be _______________ if all its entries above the main

diagonal are 0.

If all the entries of a square matrix are zero, except those entries on the

main diagonal, then we say the matrix is a _________________.