---
title: Eboard 19  Recursion with helper procedures
number: 19
section: eboards
held: 2017-10-06
---
CSC 151.01, Class 19:  Recursion with helper procedures
=======================================================

_Overview_

* Preliminaries
    * Notes and news
    * Upcoming work
    * Extra credit
    * Questions
    * PSA
* Quiz
* Lab
* Debrief

### News / Etc.

* New partners.  
* Please make sure to return your computer cards to the jar.
* I plan to have all grades back on Monday.  (Except for Exam 2, of course.)
* I've been answering questions on exam 2 and you should see many
  updates in the Q&A section.

### Upcoming Work

* [Writeup for class 18](../writeups/writeup18) due Friday at 10:30 p.m.
    * Exercise 7
    * To: <csc151-01-grader@grinnell.edu>
    * Subject: CSC 151.01 Writeup 18 (YOUR NAMES)
* NO WRITEUP FOR CLASS 19.
* Reading for Monday's class: [List recursion, revisited](../readings/list-recursion-revisited)
* Exam 2 prologue due TONIGHT at 10:30 p.m.
* Exam 2 due Tuesday at 10:30 p.m..
* Exam 2 cover sheets due Wednesday at the start of class
* Exam 2 epilogue due Wednesday at 10:30 p.m.

### Extra credit (Academic/Artistic)

* TODAY, 4:15 pm, Poet talk
* Nice Fish this weekend
* "Sita Sings the Blues," at 3:30pm on October 8 in the Gallery

### Extra credit (Peer)

* Volleyball vs. Beloit, TONIGHT at 7:00 p.m.  FREE T SHIRTS
* Women's Tennis vs. St. Norbert, Saturday at 9:00 a.m.
  (Field house or High school?)
* Volleyball vs. Lake Forest, Saturday at 1:00 p.m.
* Women's Tennis vs. Ripon, Saturday at 3:00 p.m.
* Nice Fish.  This weekend.  Marvel at the lights.

### Extra credit (Misc)

* Any Field Day (aka "This is not 10/10") event

### Other good things

* Football, Saturday at 1:00 p.m.
* Neverland Players, this weekend.
* Lunar new year celebration tonight (Sam lost his notes, thinks 6:20 p.m. in
  Harris gym with FREE FOOD and AWESOME PERFORMANCES)

### Questions

On problem 1, do we have to handle the case in which the start is larger than the end?
  : No, provided you make an appropriate precondition.

### PSA

* Stay well.

Quiz
----


Lab
---

Please discuss which switching format you and your partner will use

* Switch every ten minutes
* Switch midway through class
* Switch every problem

Whoops!  Typos in code in lab.  Sorry!

```
> (my-quotient (list 5))
5
> (my-quotient (list 5 3))
5/3 ; or 1 2/3
> (my-quotient (list 5 3 7))
5/21
> (my-quotient (list 5 3 7 5))
1/21
> (my-quotient (list 5 3 7 5 1/3))
1/7
```

NO WRITEUP

Debrief
-------

We will do the debrief at the beginning of the next class.