a = [-2, 1, 0, 0, 0; 1, -2, 1, 0, 0; 0, 1, -2, 1, 0; 0, 0, 1, -2, 1; 0, 0, 0, 1, -2];
b = [-1; 0; 0; 0; -1];
linsolve(a, b)
