f(x)=-x^3

x                  y              
-2.5               15.625             
-2.2               10.648             
-1.9               6.859              
-1.6               4.096              
-1.3               2.197              
-1                 1                  
-0.7               0.343              
-0.4               0.064              
-0.1               0.001              
0.2                -0.008             
0.5                -0.125             
0.8                -0.512             
1.1                -1.331             
1.4                -2.744             
1.7                -4.913             
2                  -8                 
2.3                -12.167            
2.6                -17.576            
2.9                -24.389            
3.2                -32.768