fastlog2Library   "fastlog2" 
 Description: 
Returns the approximation of Log2 with the maximal error of: 0.000061011436
 Reference: 
www.anycodings.com
 fastlog2(x) 
  Returns the approximation of Log2 with the maximal error of: 0.000061011436
  Parameters:
     x : float
  Returns: float, log2 of x

