Revert "Revert "Revert "Revert "Spars Matrix""""

This reverts commit 11a350a4db9ef4f060684431434316a3d6f2be33.
Revert "Revert "Revert "Spars Matrix"""

This reverts commit ec6bf9ce4936b51e60f01330e7478ad19683c1c2.