The entire domain of the function is within [-128, 128]. There does not seem to be a specific interval where unexpected behavior occurs.

For the [CODE] part, I will attempt to recreate the function's behavior using a piecewise linear function. This is an approximation, and more data points may be needed for a more accurate representation.

```python
def approx_function(x):
    if x < 0:
        return -1.25 * x / 128   # Linear interpolation between (-128, -1.333) and (0, -1.654)
    else:
        return 1.25 * x / 128    # Linear interpolation between (0, -1.654) and (128, 0.875)
```
Note that the function above is an approximation and may not match the exact behavior of the given function. It is better to test more input/output pairs to establish a more accurate pattern.