Based on the experiments, I can provide a description of the function f(x):

[DESCRIPTION]:
The function f(x) seems to act like a piecewise function. When the input value x is around 0, the function produces larger output values. For input values further from 0, the output values of the function tend to be close to 0.


[DOMAIN]:
The function has a domain between [-128, 128]. It displays an unexpected and different behavior between -4 and 4, with larger outputs in this interval. Outside this interval, the function output gets closer to 0 as the input values move further from 0.

[CODE]:
Here is Python code that approximates the behavior of the function:
```python
def approx_f(x):
    if -4 < x < 4:
        return 0.9
    else:
        return 0
```
Please note that this is a rough approximation of the behavior and it might not match the actual results exactly.