A matrix is a set of numbers arranged in rows and columns
in a rectangular or square array. The numbers and letters
which make up the array are called its elements and can be
referred to by giving their row and column.
The element in the second row and third column
of the first matrix is 8.
can be used to encrypt numerical data. Encryption is done
by multiplying the data matrix with a key matrix. Decryption
is done simply by multiplying the encrypted matrix with the
inverse of the key.