# Harwell-Boeing format for sparse matrices

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 3

2.3  0  4.2

0   1.3 2.2

3.8  0  0.5

0    0   0


Sparse Text Harwell-Boeing Format:

SVDLIBC v. 1.32

3             1             1             1             0
rra
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.