A diagonal matrix whose diagonal elements are equal, is called a scalar matrix.
Scalar matrix is a square matrix and the number of rows is equal to the number of columns in it. So, a diagonal matrix is possible by the square matrix. A diagonal matrix contains elements only on the leading diagonal and remaining elements are zeros. In the same pattern, scalar matrices contain elements in principal diagonal but those elements are same.
is a square matrix of order . It is formed by elements. The matrix is having nonzero elements on principal diagonal but having zeros as non-diagonal elements. Therefore, the square matrix is recognized as a diagonal matrix.
The diagonal matrix contains same elements on the leading diagonal. Therefore, it is known as a scalar matrix.