CSC151.02 2016S, Class 30: Other Forms of List Recursion
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_Overview_

* Preliminaries.
    * Admin.
    * Upcoming Work.
    * Extra Credit.
    * Questions.
* Lab.

Preliminaries
-------------

### Admin

* Continue partners!
* Sorry that I can't be there.  I continue to have confidence that
  our Mentors will do an awesome job.

### Reminders

* Office hours this week 
    * See http://rebelsky.youcanbook.me.
    * Ask me about other available times.
* Tutor hours
    * Sunday, 3-5 p.m.
    * Sunday-Thursday, 7-10 p.m.
* Weekly review sessions:
    * Wednesday at 8pm in the CS Commons with 
    * Thursday 10 am review session with Sam.
    * Thursday at 8pm in the CS Commons with 

### Upcoming Work:

* Reading for Tuesday
    * [Numeric Recursion](../readings/numeric-recursion.html)
* Exam 2 due TONIGHT
    * Epilogue for exam 2 due TONIGHT
    * Cover sheet for exam 2 due TOMORROW 
* Lab Writeup: Exercise 3abc
    * Send email titled __CSC 151 Lab Writeup 30 (Your Names)__
    * Do not include the underscores.
    * Send to <CSC151-02-grader@grinnell.edu>
    * Due before class on Friday.

### Extra Credit

* Send your reports to <rebelsky@grinnell.edu> with subject 
  "CSC 151 Extra Credit".  (Do not include the quotation marks.)
* Send opportunities to me before class with subject
  "CSC 151 EXTRA CREDIT OPPORTUNITY!"

#### Academic / Artistic

* Cool talk on Cryptography Wednesday at 4:15 (Math/CS)

#### Peer

#### Regular Peer (weekend things probably won't be this weekend)

* Social Dance Workshop Tuesdays 7:00-8:00 in Bucksbaum Dance Studio
* Pun club Saturdays at 4pm in Younker 
* Electronic Potpourri on KDIC Fridays at Five 
* Space Odyssey KDIC Fridays at Six
* Bollywood, Friday, 7:30-8:30, Younker
* Effective Altruism club, 2:30-3:30 Sundays in JRC 226.

#### Misc

#### Far in the Future

* Lords of the Flies, April.

### Questions

_Can I use recursion on exam 2?_

> No.  You had not learned recursion by the original due date.

_Any hints on problem 4?_

> Sure.  You want to conduct a series of tests that will make you confident
  that the `alternate-scale` procedure is correct.  That means you should
  consider drawings with (a) different shapes; (b) different positions;
  (c) different sizes; and (d) different scales.  For each variation, you
  can use the helper procedure provided in the reading.  
  
_How many tests should I write?_

> I expect about a dozen calls to the provided procedure.

_Any hints on the `drella!` procedure?_

> The `p-and-s!` procedure from the lab on collage should be helpful.
  Note, however, that you need to copy the image before you call
  `p-and-s!`.

> Because you will have to paste more than once, think about the forms
  of repetition you know (other than recursion).

> Remember that you are dealing with imags and GIMP tools.  **Do not
  use the drawing operations for this problem!**

Lab
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