## Problem with Matrix and Gauss-Seidel (Maple)

I have to solve a few equation with a Gauss-Seidel way. Unhappy thing is that my Matrix is optimized so I have only three vectors that describe matrix elements(without zero), their location in a row and numbers of elements in every row. I can't rebuild matrix because in these case optimalization doesn't make sense. I have to write code in Maple that can solve equations.
That's my vectors:

Describe matrix elements
Code:
V1 := [11, 2, -1, 1, 18, -3, 21, 2, 15, -1, 18, -2, 26]
Describe place of element in a row
Code:
V2 := [1, 4, 5, 1, 2, 1, 3, 1, 4, 2, 5, 4, 6]
Describe number of elements in ewery row(after you make subtraction amount_i=n_(i+1)-n_i)
Code:
V3 := [1, 4, 6, 8, 10, 12, 14]
Matrix of b elements
Code:
b := [1,2,3,4,5,6,7]