how to improve this simple block of code

[Xavier Morel]

Forget about the previous mail, i just saw you were converting the 
string to float beforehand, in which case he would more than likely run 
into the good ol' float imprecision issue sooner than later.

Not to mention that %g formats to scientific notation (e.g. exponential 
format with the exponent always being a multiple of 3), he'd probably 
use "%f".