graf  2, signabilita +0 -0, determinant = 2.000000, spectrum = -1.0000, -1.0000, 2.0000, ; B = [[0 1 1 ];[1 0 1 ];[1 1 0 ];];    Dpos = [[0 0 0 ];[0 0 0 ];[0 0 0 ];];    Dneg = [[0 0 0 ];[0 0 0 ];[0 0 0 ];];