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Homework exercises are absolutely key to comprehension of the course material. Important qualities of the structure of computer programs are determined, not just by mental contemplation of the programs, but by the detailed logistical efforts required to make them work. You can only begin to understand those logistical efforts by making some of them for yourself.
Homework exercises are also key to my evaluation of your work. It is impossible to receive a satisfactory grade in this course without performing well on the homeworks.
All homework assignments must be submitted using the
handin command before 11:59 PM on the due date.
If illness or personal/family difficulties delay your work, let me know as soon as possible and we can make special arrangements. A moderate amount of trouble with the computer systems is a normal part of computing, and you must budget time for it. I will give extensions only for massive computer failures, e.g. all CS Linux systems out of commission for a whole day.
I have a bimodal attitude toward lateness, modelled by mathematical
catastrophe theory. As long as lateness isn't causing logistical
problems for the class, I don't pay much attention to small
(i.e. minutes or an hour) lateness. If lateness starts causing
logistical problems, I turn into a terrible rigid authoritarian. In
particular, I may decide to close assignments at the due minute by
disabling the handin command.
handin commandThe handin command is only available on the CS
Department's GNU/Linux hosts, and will not work at other
locations even if copied there. The command is stored at
~odonnell/Teaching/Utilities/handin.
To avoid typing that long sequence each time you use it, you may
add ~odonnell/Teaching/Utilities to your execution path,
$PATH. $PATH is a shell environment variable
containing a sequence of locations to search for executable commands,
separated by colons (:). To find out the contents of your
$PATH, type echo $PATH. To add my command
directory to it, type export
PATH="${PATH}:~odonnell/Teaching/Utilities".
To avoid resetting your $PATH every time you start an
interactive shell, you may add export
PATH=${PATH}:~odonnell/Teaching/Utilities to the end
of a file named .bashrc in your home directory, or you
can modify a path assignment that's already there, e.g. to
export
PATH="$HOME/bin:$PATH:.:~odonnell/Teaching/Utilities".
handin command1To hand in your work on a particular assignment:
cd to enter a directory containing your
work.handin n file1 file2 ... where n is
the number of the assignment, and file1,
file2, .. are all the files containing the work that you
wish to hand in.handin will warn you if the assignment number is
invalid, or if one or more of the files doesn't exist, or isn't a
regular file. The files that you hand in are stored only by
their base names (the part after the rightmost "/", if
there is one), not by their paths. handin will
not warn you if you submit several files with the same base
names, and only the first one will get through the handin
properly. I'll try to create a warning in an upgrade of
handin.
If you mistype some of the file names, handin will
still put in the good ones. But you should resubmit with all of the
files, not just the ones that missed the first time.
You may resubmit as many times as you like, up until the assignment deadline. I normally only look at the last submission, but I save them all in case we have to unwind from a problem.
.scm". Each one must have a block of comments at the top
with your name shown prominently..txt". Plain text must be broken into lines of
a pleasant length: 70 characters is OK. The line breaks must be in the
form used in Unix and Linux systems, which is
different from Windows and Macintosh. You may use
your favorite text editor to compose text files, translating the line
breaks if necessary. If you don't have a favorite editor, try
emacs or xemacs on a GNU/Linux
system. I think you can use DrScheme to edit text, but it's
not a particularly good text editor for future use...ps". Lots
of word processors export PostScript. You can also produce
PostScript with the TeX typesetting
system..pdf"..dvi". DVI is the device-independent output of
the TeX typesetting system..html". The buttons on the bottom of class Web pages
provide a way to test whether your HTML satisfies the
standard. I use a variety of Web browsers, but they all display
standard HTML. I will not read nonstandard HTML
files, and the fact that they work on Netscape or
Internet Explorer is irrelevant to me.All homework will be judged (except assignment #0), not as mere evidence that you have written and executed certain programs, but as an insightful presentation of interesting ideas, using programs and their executions as part of the presentation.
It is your responsibility to execute your programs on sensible test cases that demonstrate their interesting qualities. In most of the homeworks for this course, the number of test cases should be very small. Look for the 2 to 5 examples that illustrate the appropriate concepts clearly. The choice of examples may depend on the way you have written your programs, as well as on the problem that you are solving. Strive for concise clarity, not volume or cuteness. We will discuss test cases in class as we go along.
I cooked up a graphical interface for a really bad calculator. All
it can do is add two numbers, mainly because it can't parse any other
sort of expression. When you've finished Assignment #3, you can cut
and paste your much better parser into my code, and you'll have a
pretty boring but not quite so bad calculator, that can evaluate any
expression involving +, -, *, /, ^. Even though you have solved the
problem of parsing applications of the fib, the
evaluation mechanism in the calculator doesn't know how to evaluate
it.
As the quarter progresses, I will fix up the graphical interface a bit, and you will put a much more powerful sort of evaluation into it. For now, if you really want to look at it, you'll find the code below.
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