Add COO storage format for sparse matrix.
It will save memory for V-LOR when dimension scales to billions, at the same time won't reduce performance.
The reason is that colPtrs array in CSS format matrix will occupy large memory size when the matrix is very sparse.
Add COO storage format for sparse matrix. It will save memory for V-LOR when dimension scales to billions, at the same time won't reduce performance. The reason is that
colPtrsarray in CSS format matrix will occupy large memory size when the matrix is very sparse.