CSC151.01 2015F, Class 06: Transforming Colors ============================================== * New partners! Please grab a card to identify your computer. _Overview_ * Preliminaries. * Admin. * Upcoming Work. * Extra Credit. * About Quiz 1. * Questions. * Lab. * Debrief (if time). Preliminaries ------------- ### Admin * Happy Labor Day! * The grader email has been fixed. * Quiz 1 returned. If you had trouble on part 1, please try to speak with me. We'll talk more about it in a few minutes. * I've added additional office hours at 8:30-9:00 MWF to give you more opportunities to speak with me. Still bookable at . * Before today's lab (and perhaps before every lab you do for the next week or so), please type the following command in the terminal window. /home/rebelsky/bin/csc151-update ### Upcoming Work * One reading for Tuesday: [Transforming Images](../readings/transforming-images-early-reading.html) * [Assignment 2](../assignments/assignment.02.html) due Tuesday at 10:30 p.m. * I will take questions on the assignment at the start of class today and Tuesday. * Lab writeup (due before class Wednesday) * Email to (not to me; don't forget the cs). * Subject: _CSC 151 Lab Writeup Class 6 (Your Names)_ * Problems: ____ ### Extra Credit Opportunities #### Academic * Tuesday, noon, CS Table, JRC 224C. Mobile networks in developing countries. * Convocation, Thursday at 11am, JRC 101. * Sam's convocation spiel. #### Peer Support * Pals of PALS, pals@grinnell.edu, normally Saturday at 1:30 and Mondays at 4:45. Requires sign up in advance. * Pun Club, Saturdays, 4pm, Way over Younker ### Notes on Quiz 1 * Quizzes are ... * An opportunity for me to discover what you do and don't understand. * An opportunity for you to discover what you do and don't understand. * An incentive for you to review materials. * Intended to be relatively "low stakes". * Note 1: Every real number in DrRacket is also rational. * Note 2: `ceiling` gives an inexact output when given an inexact input. * Note 3: Although I think of the card as the input to the algorithm in problem 2, I accepted anything that was argued well. ### Questions on HW2 _Is it okay that we don't have 0's after the decimal point for 2.5 or something similar?_ > That's fine. You can't force DrRacket to give you 0's at the end of an inexact number. _Should we do one or two computations for computing total minutes and total seconds?_ > Two separate computations. _How should we submit?_ > Ideally, you will copy and paste from wherever into the body of an email message. _What about the "how to add" part if we have pictures?_ > If you don't have pictures, copy and paste is better. > If you do have pictures, an attachment is okay. _Should we include the interactions when we try different contestants?_ > Yes. ### Additional Questions Lab --- * Brighter numbers have higher component values. This seems counterintuitive until you realize that it's *more light* rather than *more paint*. * Components are capped at 255. If you use a component larger than 255, you end up with 255. * No lab writeup Debrief - Some Points from Your Mentors --------------------------------------- * Scheme model: Open paren, procedure, arguments, close paren * (+ 2 3) * (+ (2) (3)) * Procedures almost always appear immediately after an open paren * Exception: When used with `o` * Sequencing: Scheme evaluates expressions inside out, which can seem backwards. * There are different kinds of values: * Strings - surrounded by quotation marks * Numbers of all sorts * Images - represented by integers * Color - represented by integers * The value `1`, could be one, or an image, or a color, ... * The value `123215413112` could be a large integer, or a color, or an image * You can name things with define * `(define gold (color->irgb "gold"))` * `(define golds (color-swatch gold (irgb-darker gold) (irgb-lighter gold)))` * `(image-show golds)`