The Enigma Machine

This is sort of old news, but I just dug far enough into my inbox to see it again. The May 30 "The Mathematical Tourist" article on the MAA website is about the Enigma Machine. I think the Enigma Machine is absolutely fascinating. In addition to having the most intriguing name of any technological innovation, the story of it's use in WWII and the allies breaking of the code is more exciting than real history has any right to be. Okay, a bit of hyperbole, but still.

The article linked has a number of links to other interesting and informative sites. I do take exception to the authors comments about Cryptonomicon. Cryptonomicon is not so much a story about the Enigma machine as it is a story about... well it's hard to explain, but the Enigma Machine features prominently. I highly recommend it. I've never read Enigma by Robert Harris, so I can't comment about that.

The Code Book by Simon Singh also has an outstanding chapter on the Enigma Machine.

21-120 Final Wrapup

Well, the semester has drawn to a close. Here are the final statistics for the course. You can see that the final grade cutoffs are

A 74.32
B 62.95
C 52.95
D 41.25

I don't use Blackboard to compute grades, but your final average, unless you have late homeworks, will be the same as your "weighted average" from the blackboard site. At least they ought to be. Until a few moments ago, Exam #3 was categorized as an "assignment" rather than an "exam", which threw off the calculation. I've corrected that though, so now, you should be able to compare your "weighted average" to the cutoffs above to determine your grade. As long as you don't have any late homeworks, that is.

Course Statistics and Graded Homework

Here is a page of statistics for the course so far. You can see (revised (downward)) grade ctuoffs for the three midterm exams, and the computed cutoffs for your cumulative averages. The final grade cutoffs may change somewhat after the final has been graded, but probably not too much.You can compare your "weighted average" from the blackboard site to the Cumulative Average grade cutoffs to see where you stand going into the final.

I think all of you uncollected graded homework is in a box outside my office door (WEH 6214). I think it includes HW#15 for sections A and B, but I'm not sure about Section C.

Finals Week Schedule

Our Final Exam is, of course, at 5:30 on Friday, May 9.

I'm trying to schedule a review session for 1:00-2:30 on Wednesday, May 7. That is a reading day, so most of you should be available.

I'll hold office hours most day's this week. The schedule is:

Monday: 11:30-1:00
Tuesday: 11:30-12:15
Wednesday: Review Session, 1:00-2:30 (tentatively)
Thursday: 11:30-1:00
Friday: 11:30-1:00

Dude This is Totally Awesome

Who would have thought that 216 magnetic spheres would be so cool.

Another Difference Engine

My last post about a real functioning Difference Engine reminded me of William Gibson's The Difference Engine, with which I was much less impressed.

A long time ago, when I had just finished reading Neuromancer, I thought The Difference Engine looked pretty cool. I'm not exactly sure what it was about, but it wasn't about Babbage's Difference Engine. As I recall, Charles Babbage is one of the characters, but he is unsympathetic to say the least. Do yourself a favor; read Neuromancer, but give this one the go by.

As an aside, this follows one of my cardinal Rules for Reading Fiction: Books by two authors are terrible.

Babbage Difference Engine #2

I, like many math/science types, have always been fascinated by Charles Babbage's Difference Engines. They were undeniably revolutionary when he designed them in 1821 and 1849. One can only imagine what might have happened had they been built.

Well, now someone has built Difference Engine Engine #2, and it is on display at the Computer History Museum in San Jose (beginning May 10).

Thomas Jefferson's Library

LibraryThing is a site that allows you to catalog books from your library, and uses that information as a basis for some sort of social networking. In their words "Enter what you're reading or your whole library—it's an easy, library-quality catalog. LibraryThing also connects you with people who read the same things."

But this post is not about LibraryThing. It's about Thomas Jefferson.

It turns out that some enterprising person who goes by the name "Thingamabrarii" has entered Thomas Jefferson's library. There are also links to other sites with information and exhibits about Thomas Jefferson's books.

There are 55 books in the Pure Mathematics category. Among these are The doctrine and application of fluxions (that's calculus to you and me), as well as Euclid's elements and some works by Archimedes. He even has some books on mathematical finance, including one by Isaac Newton: Sir Isaac Newton's Tables for renewing and purchasing the leases of cathedral-churches and colleges.

It's interesting to look over the titles, but humbling when you consider that my shelves are filled with books like this and this.

(Actually, I do read real books sometimes.)

Final Exam

Our final exam will be held on Friday, May 9 from 5:30 to 8:30 in the evening. I will provide more information about the final, and review materials as the date gets closer.

Assignment for Week #15

Well the last assignment has been posted. Get it while it's hot!