I'm dealing with SVDLIBC library. In order to compute singular values I need to specify my matrix in the Harwell-Boeing format. On Internet I have found next example:Dense Text Format:4 32.3  0  4.20   1.3 2.23.8  0  0.50    0   0 Sparse Text Harwell-Boeing Format:SVDLIBC v. 1.32                   3             1             1             1             0rra                   4             3             6             0       (8i)            (8i)            (8e)            (8e)1 3 4 7 1 3 2 1 2 3 2.3 3.8 1.3 4.2 2.2 0.5 In other libraries for sparse matrices I specified matrix as an array of non-zero values and their indices, but I can't understand how do they specify matrix in Harwell-Boeing format. Can anybody explain me how do they form two array of indices in an example above? I'm a newcomer in this field, so I'm sorry if the question seems too obvious. 
Harwell-Boeing format for sparse matrices
libraries
The Harwell-Boeing Format is described here.