The title essentially Assumes the "0" is an index  No error but also no output  Works for other values  Sign function should return 0 for zero   The input does not matter, returning zero just doesn't happen. 
The title essentially
Assumes the "0" is an index
No error but also no output
Works for other values
Sign function should return 0 for zero
The input does not matter, returning zero just doesn't happen.
