The function takes a string as an input and for each character, it outputs its position in the alphabet if the character is lowercase, and outputs "zero" if the character is uppercase. The function seems to ignore numbers and other characters.

[CODE]:
```python
def approximate_function(input_string):
    result = []
    for char in input_string:
        if char.islower():
            result.append(str(ord(char) - ord('a') + 1))
        elif char.isupper():
            result.append("zero")
    return ' '.join(result)
```