The function seems to selectively replace certain characters in the input string. Specifically, it replaces 'l' with an empty space, 'e' with 'x' and 'c' with an 'i'. The replacements depend on the position of the characters in the input string. If the character 'l' appears in an even index, it will be removed ("hello", "he  o"). If the character 'e' appears in an odd index, it is replaced with 'x' ("testing", "tesxing"). Finally, if the character 'c' appears in an even index, it is replaced with 'i' ("racecar", "racicar").

[CODE]:
```python
def approximate_function(s):
    result = ''
    for i, c in enumerate(s):
        if c == 'l' and i % 2 == 0:
            result += ' '
        elif c == 'e' and i % 2 == 1:
            result += 'x'
        elif c == 'c' and i % 2 == 0:
            result += 'i'
        else:
            result += c
    return result
```
