CSC151 2009F, Class 39: Analyzing Procedures

Admin:
* Don't forget to turn in your pretty picture of cons trees
* Reading for tomorrow: Testing Your Procedures.
* Are there questions on Assignment 7?
* I'll do a short demo of an interesting outcome of yesterday's lab.
* Rights and the environment symposium this week
  * EC for attending
* EC for attending Fetish, since one of your colleagues is running it.

Overview:
* Comparing algorithms.
* Two related metrics: Time and Number of steps.
* Counting procedure calls by printing.
* Tools for analysis.

Observation: There is more than one way to write a procedure that gives
a desired result
* Approximately a dozen strategies for rgb-darkest
* As long as they are all correct, which is "best"?
  * The most concise
    (define rgb-darkest
      (lambda (colors)
        (fold rgb-darker colors)))
  * The most efficient
    * The fewest recursive calls
  * The most stable
    * Least likely to give an error message on correct input
  * The most readable
    * Easiest to determine, for a particular audience, what it does
* Given two algorithms to solve the same problem, how do you determine
  which is the most efficient?
  * Mathematically: Form a hypothesis about the running time and prove it
    * MAT 218 teaches you how to solve recurrence relations
  * Scientifically: FOrm a hypothesis and gather data about how long the
    procedure takes to run
* Today's idea: TOols help us count