Friday, September 26, 2008

And girls...

It is fun to be a girl.
It is fun to hang out with girls.

It is hard to be a girl at an engineering school.
The guys at an engineering school tend to think of you in two ways:
1. Oooooh! a girl!
2. One of the guys.

So one needs to hang out with other girls occasionally so as to not get lost in math, and computing, and statistics, and papers, and problem solving.

Fortunately, I live with a girl and next to another house full of girls.
We brought them cupcakes this evening and had fun discussing girl things.
And laughing at the guys (C. S. Lewis was right in his assumption - that is what we do when we get together).
We have a lot of amusing guy friends.

The apples are in

And with them the pie
and the crunchy apple crisp

The pumpkin leaves grace
the tops of tall trees
And lemon ones fall to the ground

Pine cones fall on your head
(Oh, ouch!)
And squirrels haunt your steps for food

Red and purple mums appear at the stores
(Perhaps we can make tea?)
And sniffles abound with coughs and sneezes
Interrupting my daily study

Saturday, September 20, 2008

PD2 again

Crisis has been averted.
We are doing a nice happy project to encourage people to exercise more.

But the class itself took a turn for worse this past Wednesday.
We were required to watch this movie in class.
It was a quite horrible movie all about a bunch of guys doing sex and drugs on a Greek island.
Well, that wasn't the point of the was really about these group of soldiers who get stranded on this Greek island and discover that taking things easy and living the simple life is much better to their previous war-related activities and the constant fast-paced adventure they enjoyed. Several shocking scenes, however, caused me come to a different conclusion...

Anyway, now I have to write a paper about the leadership styles portrayed in the movie.

But watching movies only happens twice in the semester and I think the next one will be about some scientists, so I shall hope it will be much better.

Wednesday, September 10, 2008

PD2 = Moral Dilemma

Nobody ever told me PD2 would cause moral dilemmas!!!

Although it actually isn't a dilemma, just more of a tricky situation.

But fear not! I will not help start any Planned Parenthood groups at my school.

Now you are wondering what on earth PD2 is and what Planned Parenthood has to do with it?
Well, PD2 stands for Professional Development 2. We're required (all us engineers) to take classes that encourage professionalism and good business habits and leadership roles. The classes are split into three courses: PD1, PD2, and PD3. PD2 is mostly about leadership.
Because of this, we have a team project in which we are to do something that will have an influence in some community.
The two ideas my team has come up with thus far: encourage recycling on campus or starting a Planned Parenthood group.

I very quickly brought to the table that I was pro-life...and therefore not very likely to agree with the latter idea, although I was not opposed to raising awareness about health issues on campus.

When the idea was raised, I flew into a tailspin (an interesting maneuver with airplanes) and had to collect my thoughts so I could nicely but firmly state my disagreement. It is harder than you might think, 'cause you don't want to totally offend someone you'll be working with for the semester by shooting down their ideas (or actually, ever). But by God's grace the idea giver was receptive and understanding.

But the team is still deciding...

Thursday, September 04, 2008


And now for another excursion into the fascinating world of math and errors.
First of all, you must realize the all important fact that nearly all solutions of math problems are approximations.
I know it seems hard to imagine (at least, I kept feeling there must be some way to get exact answers). But it is true. Your computer and your calculator and your hand calculations are usually riddled with errors: rounding errors, truncating errors, data errors, computational errors, forward errors, and backward errors (and maybe a few more that I have forgotten).

This post will explore backward and forward errors.

Have you heard of functions?

Well, imagine a an oven. You put in a lumpy sticky mixture of ground-up grains, crushed olives, fermenting fungi, sodium chloride, sugars, and flammable elements combined so they are no longer flammable (i.e. H2O or "water" as it is commonly know as). You put this unlikely combination into the oven machine.
And in ~35min. a fragrant loaf of bread comes forth.

The oven did stuff to the mixture you threw in (well, not literally) and gave an output. We could call the oven a "function" (since it performs a function...baking bread) and the dough (that disgusting mess described earlier) as the input. The nicely baked bread is the output.

We could go even further. We could give the input a generic name "x" which can now stand for anything (not just bread dough, but cookie dough, brownie batter, chickens, cats, plants, 4, 7, 109, or anything else you like). And the output gets its own generic name "y". And the function even gets its own name too! It will be called f(x) (because it performs some function on x).

Now that we've got all that straight we can begin to talk about forward error.

Usually, or at least in an ideal world, you put an x in to your f(x) and get a particular y special to the particular x you put in. And this is the exact output that you would get.

But sometimes, you only get an approximation to your actual y. It's like putting in your bread dough and getting bread that was still doughy in the middle. It's only an approximation of the actual bread you wanted. Now suppose your actual bread and your doughy bread were numbers, than you could find the difference between the two of them. And that would be your forward error.

Like this:
y - approximate y = forward error

Now backward error is a little more tricky to explain. Suppose, you wanted the bread that was doughy in the it wouldn't actually be bread you were wanting. But we could suppose there is some other...thing that you might wish to make that actually produces doughy bread. Then the doughy bread would be the exact output and not the approximate output.

So then the input changes slightly.
And you get something like this:
x - approximate x = backward error
(the approximate x is the input that gives us the exact output of doughy bread)

Perhaps a visual would help?

(click on image for clearer view)