Held: Wednesday, 4 November 2015

Back to Outline 35 - Pause for Breath. On to Outline 37 - Pairs and Pair Structures.

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 36 (Source 36)

Overview

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

Administrivia

• New partners!
• Exam 2 answer key distributed last night.
• Review sessions this week:
  • Wednesday, 8pm (Caleb)
  • Thursday, 10am (SamR)
  • Thursday, 8pm (Erin)
• Why don't you use the evening tutors?

Upcoming Work

• Reading for Friday: Pairs and Pair Structures
• Exam 3 distributed for real
• Quiz 9 on Friday.
  • Named let and letrec.
  • Turtles.
  • Iteration: repeat and for-each.
• Today's Lab writeup (due before class Monday)
  • Email to grader-151-01@cs.grinnell.edu
  • Subject: CSC 151 Lab Writeup Class 36 (Your Names)
  • Exercises:

Extra Credit Opportunities

• If possible, send me these in advance.

Academic

• Any visit to the current show in the Faulconer gallery.
• Learning Deconstructed Workshop Series, Tuesdays at 11 in JRC 209.
• Any activity with Visiting Musician and Sound Artist Ellen Fullman. (Yes, that includes Drinks @ Lonnski's on Thursday.)
• Convocation Thursday: The US Labor Market is a Mess.
• CS Extras Thursday: Bluetooth, Robots, and CS 161.
• Sexual Misconduct at Grinnell College: Results from the 2013 and 2015 Sexual Conduct Surveys. 1-3 pm, November 8, JRC 101.
• CS Table next Tuesday.

Peer Support

• Is anyone cooking for ISO Food Bazaar?

Regular Peer Support

• Pals of PALS, pals@grinnell.edu, normally Saturday at 7:45 am (breakfast included), Sunday at 4:45, and Mondays at 4:45. Requires sign up in advance.
• Socrates Cafe', Saturdays, Younker, 2pm.
• Pun Club, Saturdays, 4pm, Way over Younker.

Upcoming Peer Support

• November 14, Orchestra Concert, Sebring Lewis, 7:30 p.m.
• Women's Basketball Opening Game, 1 pm, Nov. 15, vs. Silver Lake.
• One-act Festival Dec. 5 & 6.

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