Answer from cs61c-ei (Jing Chen 16669246) for Question 3
In the old days, many programmers wrote (0.5 – x) + 0.5 instead of 1.0 –x probably because of the fact that floating-point addition is not associative. Due to the nature of how the addition is done and to rules of how many decimal digits can exist, programmers must try and maintain the most accurate and precise solution possible. After all, computer arithmetic is finite. Hence, by doing it the first way, it is probably easier to achieve greater accuracy if say x was a small decimal number less than 0.5.