Computer Science 115 - Section 1 Fall 1998
Frequently Asked Questions

• Question

  Could you give me some help on how to do exercise 1.7. I tried to do an inequality ... (details omitted) ... If you could give me some help at your convenience...

  Answer

  What you want to think about is the fact that "good" is a relative concept. For numbers "relative" means how they compare multiplicatively. There is an old joke about the astronaut that returns from space after a thousand years going near the speed of light (so the astronaut has aged only slightly) and immediately calls her stock broker to see how much her account is worth. Told that it is well over a billion dollars, she is delighted, until the telephone operator interrupts to ask for a deposit of $1 million to allow her to talk for another minute... So what matters is not how big things are, but how big they are compared with some reference. That is determined, of course, by dividing the two numbers. So you should divide by the current guess in determining whether the answer is "good enough".

• Please note

  There is a typographical error on pg. 45 of SICP that relates to Exercise 1.16. It says to use the rule b^n=(b^(b/2))^2 , when it really means b^n=(b^(n/2))^2. The corresponding formula is correct in the hint on the next page in the exercise, so ignore the one on page 45!

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  ridg@uchicago.edu