## Wednesday, September 22, 2010

### Some more news

1. The Lego robotics thing won't be starting until the 4th week in October, and will only be once a month on the 4th Sunday of each month. So there will be no more news about that until then.

2. I will be presenting my work at the CS Grad Expo on October 4. I will try to get some sort of picture up then.

3. We just submitted our annual report to the National Science Foundation. If you want to see it I can try to put it up here soon.

4. I have gone to several Magic card tournaments in the past few weeks. I have started to get better at the tournaments and I actually got in first place in one of tham (out of about 12 people or so). The only problem is that now whenever I play multiplayer (that is, games with more than 2 people) everyone gangs up on me because they assume that I will beat them if they don't. It is impossible to convince them otherwise even if there is a situation where, say, I have no creatures with any useful powers on the board but the person across from me is just one turn away from using his power that will make all his creatures indestructible for the rest of the game.

5. At Belegarth, I have identified several things that I need to get better at, and I have devised a plan for doing so, as follows. These plans have not been implemented yet but I will post again as I see how they come out.

PROBLEM: Sometimes I can't remember who is on my team. Asking the target is rarely useful because it simply alerts them that I am about to shoot them. Not asking is problematic because it sometimes results in me shooting people on my own team.

SOLUTION: Take photos of as many players as possible. Write a computer program that will do the following: (1) display a random selection of these images, each labeled as "red" or "blue", then (2) display images one after another and ask me to identify which is on which "team." This way I can practice team identification.

PROBLEM: I am supposed to only "half draw" the bow back when shooting from under 15 feet. However I sometimes have a hard time determining whether it is 15 feet.

SOLUTION: Tape a piece of tape near the side of my glasses, with two tick marks on it. The distance between the tick marks will be calibrated such that the apparent distance between the tick marks is equal to the apparent height of an average-height target at 15 feet. (The principle is similar to the principle described here, except that I don't need to know the exact range, just know whether it is more or less than 15 feet.)

PROBLEM: Different people have given me conflicting answers as to what exactly "half draw" means. Basically, the "draw length" is the distance between the nock (the place where the arrow is attached to the bowstring) and the front of the handle of the bow when you draw it. The maximum allowable draw length for full draw is 28 inches. The question is that even if you just put the arrow on the bow in the "neutral position" and don't draw it at all, the "draw length" is not zero; it is about 7 inches or so (because the bow is curved.) So does "half draw" mean 14 inches (halfway between 0 and 28) or 17.5 inches (halfway between 7 and 28). I have gotten both answers from different players, and sometimes they tell me one thing but when I have them demonstrate and measure it, it's clearly something else.

SOLUTION: Bring a tape measure to practice. Have as many archers as possible demosntrate where they think "half draw" is, and measure it. Take the average of all these measurements, then put a "half-draw mark" on the arrow at that location. Get the half-draw mark checked by a herald (that's like a referee). Additionally, in case I am playing and there is a different herald who disagrees with the first herald on where half-draw is, bring replacement tape so I can re-mark the arrows if necessary.

## Thursday, September 2, 2010

### A new semester

So a new semester just started. A few cool things have been going on:

1. I signed up for two classes: "Adaptive + Multigrid Methods" with Luke Olson and "Finite Element Analysis" with Dan Tortorelli.

The class on Iterative+Multigrid Methods is about techniques for solving large systems of linear equations. Large systems of linear equations arise a lot from approximating a partial differential equation by a separate linear equation at each point on the mesh. "Iterative" means that you solve the equation by coming up with an approximate "guess" and then repeatedly improving the "guess" until you get close enough to the solution. "Multigrid" means that rather than just using one mesh, you have several different meshes of different sizes, and you use the solution to the coarser mesh (which can be computed faster) in order to get a better guess for the solution of the finer mesh.

The Finite Element Analysis class is in the mechanical engineering department, so most of the students are mechanical engineering students. It is interesting to learn more about how the mathematical techniques I am learning about are actually used to model physical systems, although one problem (from my perspective) is that since most of the students are not computer science students a lot of time is spent going over basic programming concepts that I've already seen over and over. For example today the professor spent most of the class just explaining how to write a program that reads input from a data file and puts it into a matrix.

2. As for my research, we have gotten to the point where we can produce reasonably good looking visualizations of the meshing process. Once I finish that part (probably in the next few weeks) I am planning on making a web page where I can put them up so you can look at them.

3. In Belegarth, last week there was the Numenor "Opener" to mark the start of the semester, where lots of people come, including some from other groups, and they do lots of different battles. One of the battles was a "Unit Battle," where the different "units" (units are groups of people that fight together and often have distinctive uniforms) all fight. For that battle I temporarily joined a unit called House Valdemar. During that battle the leader of that unit (who is also the owner of one of the game stores I play Magic at) was so impressed with my archery skills he asked me to join the unit. The way it works is that now I am a "petitioner", and after a couple months the members vote on whether to keep me in as a full fledged member. So I guess it's kind of like a fraternity (not that I would know).

4. I have volunteered to be an instuctor for a 4-H club activity that teaches kids how to build robots using Lego Mindstorms toys. The way this happened was that one of my classes is in the engineering building, so when I was getting out of class I saw a flyer up on the wall advertising this, and it sounded really cool. It's going to be an hour once a week for 6 weeks, and it probably going to start in a couple weeks or so (they haven't set up the schedule yet). I did check to make sure it will end before December so it won't interfere with our vacation plans.