Compressed Column Storage

Analogous to CRS, there is compressed column storage (CCS), which is also called the Harwell-Boeing sparse matrix format [139]. The CCS format is identical to the CRS format except that the columns of $A$ are stored (traversed) instead of the rows. In other words, the CCS format is the CRS format for $A^T$.

The CCS format is specified by the $3$ arrays {val, row_ind, col_ptr}, where row_ind stores the row indices of each nonzero, and col_ptr stores the index of the elements in val which start a column of $A$. The CCS format for the matrix $A$ in (10.1) is given by

val	10	3	3	9	7	8	4	8	8 $\cdots$ 9	2	3	13	-1
row_ind	1	2	4	2	3	5	6	3	4 $\cdots$ 5	6	2	5	6

col_ptr

1

4

8

10

13

17

20