-10 10 -10 10
-0.5    0         0       0.5       -0.5       3       
0.4     -0.4      0.4        -0.4      0.4        -0.4
-0.4     0.4      -0.4        0.4      -0.4        0.4
0.5     -0.4       0.5        -0.5      0.5       -5