Held: Friday, 14 November 2014

Back to Outline 40 - Vectors. On to Outline 42 - Higher-Order Procedures, Revisited.

Summary

We consider Scheme's random procedure, how one might use that procedure in writing simple simulations, and how the procedure can be used to generate "unpredictable" images.

Related Pages

• Reading: Random Drawing
• Lab: Random Drawing
• EBoard 41 (Source 41) (HTML 41)

Overview

• Random art.
• Why use randomness.
• The random procedure.
• Simulation.

Administrivia

• Continue partners.
• I've brought copies of "Visual Modeling with Logo" for you to look at. It's one of my favorite examples of the kinds of things you can do with turtle graphics. You can borrow a copy if you'd like, but please be careful with the copy (the book is out of print and expensive to replace).
• It's Friday. It's time for another PSA.

Upcoming Work

• Lab writeup: Exercise 4c, http://bit.ly/151-2014F-w41
• Reading for Monday:
  • Design Patterns and Higher-Order Procedures
  • Learn how to write map and all.
  • One of the parts of 151 that the faculty find most important (and elegant)
  • One of the points at which people who have previously programmed in another language really get it that Scheme is different.
• Part one of the project due Monday night.
  • Sketches due in class on Tuesday.

Extra Credit Opportunities

Academic

• CS Table Today: Shellshock
• CS Extras Next Week: Weinmaniacs on Text Recognition in Maps
• CS Table next Friday: ???
• CS Extras Tuesday the 25th: Summer Opportunities in CS

Peer Support

• Football, Saturday at noon vs. Lawrence.
• Karan's radio show 11pm Thursday nights on KDIC
• Evan's radio show 5pm Friday nights on KDIC (TODAY!)
• Donna's radio show Sunday midnight on KDIC
• One acts, coming soon

Miscellaneous

• VP Student Affairs Candidate Open Sessions
  • Today, 4:15, JRC 209
  • Wednesday, 4:15, JRC 209
  • Friday next, 4:15, JRC 209

Randomized Images - The Theory

• Non-mainstream art philosophy: The images that come from random processes (or from nature) can be as interesting as the images that come from artists who intentionally plan the canvas.
• One important movement: Dada. (Early 20th century; also a reaction to facism and industrialization and ...)
  • An example: Tristan Tzara's "How to make a Dadaist Poem"
• Disclaimer: After creation by random processes, some filtering of good from bad often happens.
• Disclaimer: Many of the random processes still include some artistic intention.
  • Jackson Pollock's painting style provides an interesting combination of intent and randomness.
• Modernized/computational suggestion:
  • Randomized processes can provide inspiration
  • The ability to constrain some aspects of the process can provide a new mechanism for creation.

The random Procedure

• Scheme helps us by providing a (random n) procedure.
• n must be a positive integer.
• random returns an integer between 0 and n-1, inclusive.

Randomized Images - Practice

• Many of the procedures we've written or used have numeric parameters.
• Those parameters can be generated "randomly".
• Many of the procedures we've written take one of a restricted number of inputs (e.g., there are only so many brushes).
• Those inputs can also be selected "randomly".
• Demo: Randomizing the brush

Other Uses of Randomness

• We often use randomness in simulating unpredictable events, such as the rolling of an unbiased die.
• More requently, such randomness is used in larger-scale simulations.
• We'll stick with images, though.

Lab

• Do the lab