code: public static int optimalNumOfBits(long inputEntries, double fpp) {
  		int numBits = (int) (-inputEntries * Math.log(fpp) / (Math.log(2) * Math.log(2)));
  		return numBits;
  	}
docs: Compute optimal bits number with given input entries and expected false positive probability.
  
  @param inputEntries
  @param fpp
  @return optimal bits number