SPARSE MATRICES

Matrices along with good number of zero entries are called sparse matrices.

Refer the following matrices of Figure

(a)                                                                   (b)

Figure: (a) Triangular Matrix (b) Tridiagonal Matrix

A triangular matrix is a square matrix wherein all of the elements either above or below the main diagonal are zero. Triangular matrices are kind of sparse matrices. A tridiagonal matrix is also kind of square matrix wherein all of the elements except for the chief diagonal, diagonals on the instant upper & lower side are zeroes. Tridiagonal matrices are also  a kind of sparse matrices.