The function assigns numerical values to input strings based on a pattern or rule that is not immediately apparent.

[CODE]:
```
def f(x):
    # Calculate numerical value based on pattern or rule
    value = 0
    for char in x:
        value += ord(char)
    return value
```

Please note that this code is an approximation and may not accurately reflect the exact behavior of the function. Further experiments and analysis may be necessary to determine the precise pattern or rule used for assigning the numerical values.