CSC151.01 2007S, Class 02: An Introduction to CSC151

Admin:
* Due: HW 1
* I have started to respond to your questions.  
  When appropriate, I've also posted my responses to a Web page.
* EC: Thursday, 11 a.m., Johanna Meehan on vocation (or lack thereof).
* EC: Thursday, 4:15 p.m., John David Stone on the game of life.
* Reading for Wednesday: The DrScheme programming environment.
* Attendance

Overview:
* Lessons from PB and J.
* Common parts of an algorithm.
* About the course.
* Lab.
* Some administrative details.

/Old Lessons from PB&J/
What might you have learned from this exercise?
* Know your data - E.g., we had to know that the jelly jar had a 
  pop-open lid (or might have a pop-open lid) and the direction in
  which the twisty-tie was oriented.
* Be precise - ambiguity leads to doom
* Incorrect or vague instructions can lead to infinite computation
  * Be particularly careful about these instructions
* Working in teams often leads to better solutions
* It can still be fun when things go wrong
* Computers are SENTIENT AND MALICIOUS

/New Lessons/
* It's very strange to describe something when the thing you're
  talking to lacks both basic knowledge and common sense
  * Know what basic knowledge your audience (the computer) has
* If you're not precise, things can be a disaster.
* There's more than one way to solve a task.
  * We may then need to compare different solutions/algorithms.
* Algorithms often describe a process or a sequence,
  * If something goes wrong early, the errors propagate
  * It is often better to write an algorithm in parts, and test
    each part in turn.

/Alternate Lessons: What we see in many algorithms/
* An algorithm typically takes INPUT and produces an OUTPUT value
* We NAME the intermediate values when we write algorithms,
  and we try to choose good and unambgiuosus names
  Named values are called "variables"
* We SEQUENCE operations in algorithms
  * Some sequencing is implicit, rather than explicit
* We TEST conditions and make different decisions based on those
  conditions
* We REPEAT activities, often until some state is reached
* We break complex algorithms into SUBROUTINES
  * Subroutines can be used in multiple situations
* Know and rely on some BASIC OPERATIONS

/What is CSC151?/
* A first course in computer science
  * First course: No prior experience necessary
  * Computer science: Algorithms
    * For assigned solutions
	* We hope for other problems, too
* Why should a liberal arts student take 151?
  * Writing algorithms well requires very different thoguht processes 
    * Small details have overwhelming import
	* Need to balance small and big pictures
	* Think carefully about process
* How do we help you learn this stuff?
  * Labs, labs, and more labs
  * Collaborative
* "There's more to life than CS"
  
/Lab/

* Issues:
  * When the computer refuses to start Firefox/Iceweasel, ask for help.
* Obligatory "joke"
  * If computer science is the study of precise instructions, why don't
    computer science faculty write labs that are precise, clear, and
	work for every circumstance?