CSC151.01 2015F, Class 04: Computing with Symbols and Numbers

Overview

Preliminaries

I'll attempt attendance while wandering around the room.
Please grab a card to identify what computer you are on today (through Friday).
- Maps are scattered around the room.
- Put the card in the jar once you've read the name of the computer.
My normal office hours are MWF 11:00-11:50. You sign up for those at https://rebelsky.youcanbook.me. My paperwork times are M-F, 8-9 am. Those are probably the best times to try to schedule alternate appointment times. Check my schedule for more. (I'll give up the occasional class prep time if necessary, but I prefer advance notice.)
Mentor Review sessions Wednesday 8pm and Thursday 8pm in the CS commons.
- Mentors usually prepare discussion questions and sample quiz questions.
Sam review sessions Thursdays at 10am in our classroom.
- Sam does not prepare at all, but answers almost any reasonable question.
EG wants you to know that I have been known to phone students who don't show up for class.
At 10:40, the mentors will remind me to announce the writeup problem.

Two readings for Friday: Design and Color and RGB Colors
Assignment 2 is ready. Your assignment partner is the person (or people) at the same computer as you.
- I will take questions on the assignment at the start of class on Friday and Monday.
Quiz Friday!
- 10 minutes.
- Topics:
  - The parts of an algorithm.
  - The form of Scheme expressions.
  - Arithmetic operations in Scheme.
- Sample forms of questions
  - Given this algorithm, identify these parts.
  - What output will I get for this Scheme code?

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
Orchestra September 25 or something like that

How do you know if the square root procedure behaved properly?

Ask scheme to multiply it.

Use a different device.

Sam says "Always ask yourself 'is this the right answer?' 'how do I know?' 'how can I check?'

What were some things you discovered about Scheme?

In the DrRacket development environment, we have two panes: Interactions and Definitions.
- Definitions are for more permanent things (e.g., definitions)
- Interactions are for interactive experimentation
History - ctrl-uparrow and ctrl-downarrow
You can't use a name unless you've defined it, and you must get the name just right.
If you don't click "Run", you don't get the latest definitions from the definitions pane, but DrRacket puts a big yellow warning to let you know that.
In Scheme, we write expressions as (FUNCTION PARAM1 PARAM2) as opposed to the tradition of FUNCTION(PARAM1,PARAM2)
Scheme has a lot of built-in operations, but not everything you'd expect.

A tip from your helpful mentors: Copy and paste in to definitions, and then "comment out".

A tip from your helpful mentors: Save early and often!

A tip from your helpful mentors: Cite us!

Do problem 2f
Email subject: "CSC 151 Lab Writeup Day 4 (Your Names)"
Email recipient grader-151-01@cs.grinnell.edu
- Don't forget the cs!
- Due before class on Monday, but do it today if you can.

Subject: