The domain of the function seems to be the entire range of numerical inputs, from -128 to 128. However, we can observe that there is a significant change in behavior around the x = 0 mark. 

[BEHAVIOR]: Before x = 0, the function seems to be decreasing rapidly as the input approaches -128, then starts to level off as it approaches 0. After x = 0, the function starts to increase rapidly as the input approaches 128. 

Let's try to approximate the behavior of the function using a piece-wise function:

[CODE]:
```python
import numpy as np

def f(x):
    if x <= 0:
        return -0.0135 * x ** 2 - 0.009 * x
    else:
        return 0.028 * x ** 2 - 0.005 * x
```

This piece-wise function considers two different behaviors for x <= 0 and x > 0, which seem to be more consistent with the experimental results we obtained. However, please note that this is just an approximation and the actual implementation of the function in the ./temp2/function.py script may involve more complex operations or different mathematical formulas.