A sparse matrix is a matrix with mostly zero elements, where a dense matrix has mostly non-zero elements. The sparsity of a sparse matrix is the percentage of zero elements it contains. Sparse matrices can save substantial memory by only storing the locations and values of non-zero elements, using formats like compressed row storage that use three one-dimensional arrays.

1. What is Sparse Matrix?
 Sparse matrix is a matrix in which most of the element
are zero.
 By contrast if the most element are non zero then matrix
is Dense.
 Sparsity of sparse matrix is the number of zero valued
elements divided by total no. of element.
 The following sparse matrix contains only 16 nonzero
elements, with 84 zero elements. Its sparsity is 84%, and
its density is 16%.
SPARSE MATRIX

2. Storing Sparse Matrix in memory
 A matrix is typically stored as a two-dimensional array.
 In the case of a sparse matrix, Reduction of substantial memory requirement
can be realized by storing only the non-zero entries.
 There are different format in data structure to store Sparse matrix.
 Sparse matrix is stored in three one-dimensional arrays (using CSR format)
 Most of the general format for storing sparse matrix is CSR(compressed Row
Storage)