# Class 42: Analyzing Procedures, Continued

Back to Analyzing Procedures. On to Association Lists.

This outline is also available in PDF.

Held: Tuesday, April 20, 2010

Summary: We continue our explorations of algorithm analysis.

Related Pages:

Notes:

• Reading for Wednesday: Association Lists.
• Are there final questions on the project proposals?
• You might enjoy this cartoon.
• EC for Thursday's Thursday Extra on Media Computation (Thursday, 4:30, Science 3821).

Overview:

• Comparing algorithms.
• Two related metrics: Time and Number of procedure calls.
• Tools for time analysis.

## Choosing an Algorithm

• At this point, we've seen that there are often multiple algorithms that solve the same problem.
• What criteria might we use to choose an algorithm?
• To be discussed in class.
• One of the ones that many programmers emphasize is efficiency:
• Measured in terms of time
• Measured in terms of memory usage
• Measured in terms of procedure calls

## Overview

• When comparing algorithms, we often care which one is faster.
• We can analyze by hand.
• We can analyze by using a library written at Grinnell.
• We can carefully study the code and predict (covered in future CS courses)

## Steps in Automating Analysis

• Replace `define` with `define\$`.
• Type `(analyze exp procedure)`
• Alternately, type `(analyze exp)`.
• Warning! Due to a bug in `define\$`, you can't use it with procedures that use symbols.

## Lab

Back to Analyzing Procedures. On to Association Lists.

Disclaimer: I usually create these pages on the fly, which means that I rarely proofread them and they may contain bad grammar and incorrect details. It also means that I tend to update them regularly (see the history for more details). Feel free to contact me with any suggestions for changes.

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Samuel A. Rebelsky, rebelsky@grinnell.edu

Copyright © 2007-10 Janet Davis, Matthew Kluber, Samuel A. Rebelsky, and Jerod Weinman. (Selected materials copyright by John David Stone and Henry Walker and used by permission.) This material is based upon work partially supported by the National Science Foundation under Grant No. CCLI-0633090. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. This work is licensed under a Creative Commons Attribution-NonCommercial 2.5 License. To view a copy of this license, visit `http://creativecommons.org/licenses/by-nc/2.5/` or send a letter to Creative Commons, 543 Howard Street, 5th Floor, San Francisco, California, 94105, USA.