Computer Lab 1
Friday, September 2
Guidelines
Our system administrator has some rules and guidelines
about using the computers in Weber 205.
Please read and follow them!. Most of these are common
sense. I'd particularly like to draw your attention to a few of them:
- If you are using a math or stat class account, make sure that the
MATHSTAT2 domain is selected when logging in.
- Always log out when you leave (Start -> Log out/off ). There is also
a 30 minute inactivity logout.
- Please don't give out your section password to anyone else. The
passwords should be easier to remember this year, so please don't
write them down (if at all possible). If you do write them down,
please keep them safe.
- If you discover a problem in the lab, please tell the instructor, the
proctor or mail lab@math.colostate.edu.
- Any abuse of the resources (cracking/hacking, excessive and
non-related printing, offensive material, etc.) makes life miserable
for everyone, so please don't do it.
- Hacking (or cracking for you pedants), misuse of the resources,
etc. will result in your account (or your class section's account)
being disabled. The CSU Interim
Computer and Networking Acceptable Use Policy is the Riot Act denoting
what you shouldn't be doing.
- Please don't steal anything, not even a mouse pad. Anything that we
have to replace comes out of some pocket leaving that much less for
other things.
- This lab is for math and stat people only and for mathematics and
statistics work only. No, we won't kick you out for playing an occasional
online game nor for your daily tromp over to www.whatever.com; however,
the lab is meant for classwork, labs, assignments and research, not
web chat, resumes and Half Life.
Getting started
We'll be working with crypto.mws, a Maple worksheet which
accompanies our textbook. You need to place a copy of it in
c:\temp\, so that you can work with it.
local, temporary directory so that you can work with it. Here are two
ways two accomplish this.
- Download it directly from here.
- Copy the class-wide copy of the worksheet to the temporary
directory on the computer you're usin:g
- Open (My computer -> Math on Pop G: -> m360)
- Open (My computer -> local disk c -> temp)
- Copy crypto.mws from the former to the latter.
Now start Maple 9.5, either by double clicking on
crypto.mws or by starting Maple directly, and then opening
the file.
Hit return somewhere in that page, and don't panic when lots of
text scrolls by.
Notes on Maple
Maple is an incredibly powerful system for mathematics. Play around a
bit, and try and get a handle on how the syntax works. Don't be
nervous -- it's impossible to break the thing! Here are a couple of
gotchas:
- Commands have to end with a semicolon. So, to find the sum of 2
and the following number, type:
2 + 3 ;
followed by the return key.
- To assign a value (or expression) to a variable, use the
assignment operator :=. Thus, if you want to record the value
of a computation, use something like
bigsum := 2 + 3;
To find out the value stored in this variable, just type
bigsum;
- Multiplication and exponentiation are denoted by * and
^, respectively.
So, horse around with Maple for a bit. If you like, you can work your
way through (part of) the built-in tutorial, by going to Help ->
Basic How-To. There's also a decent introduction in Appendix B of
Trappe and Washington.
Exercises
The file crypto.mws -- documented in Appendix B of the text --
contains a number of small programs which make it easier to play
around with some of the ciphers from class. Your assignment for
today:
- 2.14, problems 1, 2.
- 3.14, problems 1, 2, 4.
-
How to hand things in
The full text of your session is simply way too long. Open a new
worksheet, and copy in your answers to:
- 2.14 2.
- 3.14 2.
- The problem involving 3x+5.
Print this, and hand it in.
Other directions
Here are some other things to try if you finish ahead of schedule.
- Fix numbers a and n, and compute
aj mod n for various exponents
j. What do you notice?
- For different n, how many j are there,
j= 1...n, such that gcd(j,n) = 1. Do you
see any patterns?