• New partners (who will also serve as homework partners)!
  • Separate cards for those who do and do not want a HW partner

Overview

• Preliminaries.
  • Admin.
  • Upcoming Work.
  • Extra Credit.
  • Questions.
• Lab.
• Debrief.

Preliminaries

Admin

• Quiz Friday! Conditionals, higher-order procedures and let.
• Review sessions Thursday 9:00 a.m., 1:15 p.m., and 8:00 p.m.
• Office hours Today at 10:00 a.m.
  • http://rebelsky.youcanbook.me
• Our graders say
  • "Please limit your lines to eighty characters!"
  • "Remember that we are going to copy and paste your work into DrRacket. So don't add things after you copy and paste from DrRacket."
• Your peers say
  
  • "It's really helpful to save your work from the interactions pane."
  • "Copy-paste-comment"
• I plan to distribute an answer key to HW 5 tonight (or when the last homework comes in).

Upcoming Work

• Homework 6.
  • Due Tuesday at 10:30 p.m.
• Exam 2 to be assigned in a week.
• Lab writeup for today: Problem 3 http://bit.ly/151-2015S-lab22
• Reading for Friday
  • Building Data Structures with Heterogeneous Lists

Extra Credit Opportunities

Academic

• Pioneer Diversity Council Diversity Dialogue, 8:30 p.m. Thursday the 26th, Main Quad "Academic Athletes and Academic Students".
• CS Table Friday - Art, CS, and Artificial Intelligence.

Peer Support (Morning Section)

• Julia's radio show, "The Hot Box". Wednesday night/Thursday morning 1:00-2:00 a.m.
• Host a prospie.
• Indoor Track this Saturday
• Neverland Players Friday and Saturday at 7:00, Sunday at 1:30 and 7:00. Tickets at Bucksbaum. Get one before they sell out.
• Nobody Gets Hurt, a show with an audience of one. Info on trying to get one of the tickets is on the posters.
• Orchestra in a week and a few days.
• Grinnell Singers Sunday at 2pm. Handel's Esther. Maybe Sebring Lewis.

Other Good Things

• Jazz band Thursday night in Gardner.

Questions

Will you add my cool event above?

Done.

Lab/Debrief

How do I generalize my blend?

            Start           Mid             End
    Column  0             width/2           width
    BlaBlu  0                               255
    ??      128                             255
    ??      64                              196

How can I check my pixel values for a blend?

    > (define blend (horiz-black-blue-blend 100 100))
    > (map (lambda (col) (irgb->rgb-list (image-get-pixel blend col 50)))
           (iota 100))

Many of you computed a multiplier using (/ 256 width) (/ 255 width). Is there a problem with that approach? (Hint: What if width is 2?)