University of Virginia, Department of Computer Science CS200: Computer Science, Spring 2003

Notes: Friday 21 February 2002

• End of class today: Exam 1 out
• Monday, 24 February, 2:00PM: Exam 1 due
• Before 10 March: Read rest of GEB part I (Chapters 2-4 and 6-9, in addition to Chapters 1 and 5 you have already read).
• Friday, 14 March: Problem Set 5 (out Monday)

If you think reading Science's Endless Golden Age would be worthwhile for all incoming SEAS students, it is one of the nominees for next year's SEAS common reading experience. You can send your thoughts on the choice for the common reading experience to your student representitives (Catherine Hovell, hovell@virginia.edu and Shan Wu, shan@virginia.edu) or the chair of the committee (James Lambert, lambert@virginia.edu).

Questions
Would PS4 be illegal in France?

How much work is the simulate the universe procedure?

How much work is the solve the peg board puzzle procedure?

Secrets of the Universe
```(define (computing-power nyears)
(if (= nyears 0) 1 (* 1.587 (computing-power (- nyears 1)))))
;;; doubling every 18 months = ~1.587 * every 12 months

(define (simulation-work scale)
(* scale scale scale)) ; Simulation is O(n^3) work

(define (log10 x) (/ (log x) (log 10))) ;; primitive log is natural (base e)

(define (knowledge-of-universe scale) (log10 scale))

(define (find-knowledge-of-universe nyears)
;;; Size of simulation that can execute in nyears
(define (find-biggest-scale scale)
(if (> (/ (simulation-work scale) 1000) ; we can simulate size 10 universe today
(computing-power nyears))
(- scale 1)
(find-biggest-scale (+ scale 1))))
(knowledge-of-universe (find-biggest-scale 1)))
```
Some Golden Ages
 CS 200: Computer Science Department of Computer Science University of Virginia Circle Fractal by Ramsey Arnaoot and Qi Wang cs200-staff@cs.virginia.edu Using these Materials