This outline is also available in PDF.
Held: Tuesday, January 26, 2010
Summary:
Today we begin to consider the content and structure of the course. We
also prepare ourselves to use the Linux workstations.
Related Pages:
Notes:
- I have not started reading through your answers to the introductory survey. Expect answers to questions Friday.
- To read for tomorrow's class: The GNU Image Manipulation Program.
- Are there questions on yesterday's class?
- Are there questions on getting access to the stuff I type on the overhead?
Overview:
- Lessons from day one.
- Common parts of an algorithm.
- About the course.
- Getting started with Linux.
- Some administrative details.
What else did you learn from the PB&J exercise?
- As you may have noted, there are some common aspects to algorithms.
That is, there are techniques that we use in many of the algorithms
we write.
- It is worthwhile to think about these algorithm parts
because we can rely on them when we write new algorithms.
- As we write algorithms, we like to name things.
- Sometimes we use long names, such as
the piece of bread in
your dominant hand
.
- Sometimes, we use shorter names, such as
bread-dom
.
- As we start to write more formal algorithms, we will need
techniques for noting which names we are using and indicating
what they name (and, sometimes, what kind of thing they name).
- We call these named values variables, even though they
don't always vary.
- We need to be careful to use unambiguous names. Recall the
problems with using
it
in your descriptions.
- Many algorithms take data as input (and generate other data
as output).
- Your smiley-face algorithms might take the size of the face (or board)
as input.
- A
find square root
algorithm would take a number as input.
- A
look up a telephone number
algorithm might take a phone
book and a name to lok for as inputs.
- In each case, the algorithm should works on many different inputs.
- The algorithm works as long as the input is
reasonable
(we can't find the square root of a piece of bread,
we can't make a sandwich with pi).
- We call these inputs parameters.
- At times, our algorithms have to account for different conditions, doing
different things depending on those conditions.
- In our PB&J algorithm, we had to consider the type of lid for the jar.
- We call such operations conditionals.
- Conditionals typically take either the form
if some condition holds then do something
- Here's a slightly more complex form
if some condition holds then do something otherwise
do something else
- At times, we need to decide between more than two possibilities.
Typically, we organize those as a sequence of tests (called guards)
and corresponding things to do.
- At times, our algorithms require us to do something again and again.
- For example, you told me to repeatedly twist the jar top.
- We call this technique
repetition
.
- Again, repetition takes many forms.
- We might do work until we've reached a desired state.
- We might continue work as long as we're in some state.
- We might repeat an action a fixed number of times.
- You can probably think of many other forms of repetition.
- As in the jar top example, you need to be careful to ensure that your
repetition terminates.
- Many algorithms require common actions for their operation.
- Most of you wrote a common
How to open a jar
action.
- If we were going to make lots of sandwiches, your instructions would
become a common action.
- We can write additional algorithms for these common actions and
use them as part of our broader algorithm.
- We can also use them in other algorithms.
- We call these helper algorithms
subroutines
.
- Computer Science 151 has a number of goals
- To introduce you to fundamental ideas of computer science: abstraction,
algorithms, and data
- To enhance your problem-solving skills and give you experience
in formal representation of problems and solutions.
- To introduce you to two primary paradigms of problem solving:
functional and imperative.
- To give you some programming skills that you can apply to problems
in other disciplines.
- To improve other learning and thinking skills (as we hope all
Grinnell classes will do).
- I expect and hope that you will find CSC151 different from any class
you've taken in the past.
- We use a different format than many classes: a collaborative,
workshop-style format. (You may have seen this format in other
introductory science courses; we do it somewhat differently.)
- Computers and computer science also require you to think differently.
I expect that you'll exercise some brain cells you may have forgotten
you have. (And after all, isn't liberal arts education an exercise
in thinking in as many ways as you can?)
- Like most computer science courses, CSC151 will have both theoretical
and practical components. I hope you will enjoy relating the two.
- And, hey, we're going to make pretty pictures, too.
- We'll break about midway through today's class to get you set up
working with our Linux computers.
- This
lab prep
is somewhat pointless and annoying, but also necessary.
- Do the lab.
I am not sure whether or not I will cover these topics in class.
They are included for your edification.
- Please refer to the course web site
for more details.
- Teaching philosophy: I support your learning.
- Policies
- Attendance: I expect you to attend every class. I understand that
sometimes you have to miss. Let me know
when you'll miss class and why.
- Grading: I'm a hard grader. I don't grade everything.
- Course web.
- Etc.
- Daily work
- Attend class, work on lab and participate in discussion.
- Finish the lab in the evening.
- Do the reading for the next class in the evening.
- The quizzes
- Every Friday, plus a few pop quizzes
- The exams
- Three take-home exams during the semester. Plan to spend
four hours on each one.
- An optional final to make up for a bad exam grade.
- Take all three exams anyway.
- The labs
- The homework
- Weekly, due on Wednesdays
- Academic honesty
- Core to the academic process.
- The college's basic policy: Cite carefully.
- My basic policy: Don't cheat. (Also: It's usually okay to work with
others, provided you cite them.)
- Read my handout on
academic honesty carefully.
;
