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Cosine matrix

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Sep. 30th, 2004 | 03:09 am
mood: contemplativecontemplative

I haven't done much of an entry in a long time. There is so much of a tendency to think that if I can't update with the whole of everything I have done since my last entry that why bother writing at all. I managed the will to skip that a few times, only writing about what was on my mind at the moment, and now I want to do a little bit of a backlog, and a little bit of current.

My girlfriend was in town for a long time. I almost completely abandoned all of my regular routines while she was here. I found myself doing things I didn't used to think I could do on an almost daily basis. I found so much strength in having my ideas, and actions approved of instantly instead of using up so much time in self doubt.

When Catherine left I was very sad. She has made my life so much better. I have someone to share my feelings with. I can tell her things that I wouldn't admit to most people, and I feel better for it. I am more confident, and more alive just because I know her.

I had a distraction in the form of hard work for the first few days, and that kept me distracted from the feelings I was sure to have. A little later I felt motivated to use the new strength she gave to me to further my projects. I learned a significant amount of programming. Then I did something out of place for me. I went on a little adventure. I made a visit to Reed college, and took the tour. I have heard many good things about the school over the years. Also my one class visit to the nuclear reactor years ago where I got to look down at the glowing reactor core in the bottom of a pool of water has stuck in my mind not because of the campus, but because of the students, and how well my interaction was with a teacher there. I have been curious about the place ever since, and I wanted to see the rest of it. I liked what I saw, but I don't think I can make a decision until I really talk to some of the teachers there. Because of my visit I started getting mail from Reed, and I started thinking about reasons I might go there. I started writing about it, and I think I got up to 9 pages. I never quite formulated it into essay form. I decided I needed to answer some questions before I could finish it.

I thought about how maybe I should be going back to school in a serious way, but I wasn't ready to answer the question of weather I should be going to Reed, and classes had started there anyways. I thought I needed to go to community college because that was what I could get into. I thought I should take a class on writing because that is where I have the most difficulty, and I should take a class on math because that is what I am best at. The problem was that the test at PCC didn't even have questions on the level of math I had already taken, and so it could only test me into a significantly lower class than the level I felt I was at. It would both have hurt my pride too much, and bored me to death. So I called up the school, and found out that I could get into the class if I could convince a teacher of the class that I could handle it. I thought that I should do some review to get ready. I was taking too long to get through it, and I would feel so bad about taking too long that I was too depressed to start. It was a terrible feedback loop I got myself into. A loop that I know very well because it has plagued me much of my life. I have never been able to really do any mastery of math on my own for this same reason I think. I did plod on though. I my ability to keep coming back, and trying again keeps getting better. I figured something out in this process. I can get so much more done if I start out happy. For a while I would get myself happy by watching a movie, or something. Then I figured out I could be happy just by not thinking myself into sadness when I don't need to.

I ended not being done with review up to the point I meant to be at, and tried to get into a lower class than I set out to get into, and I didn't get into any class at all because by then everything was full.

Somewhere around then I did the labor thing again which distracted me a lot. It was helping a friend move. I think I picked up their germs, and I was sick for the next week. Now that I am finally feeling better I have picked up trying to learn something again.

It is much easier to start when I feel pretty good about myself. I think I can actually learn a great deal more than I used to be able to on my own. I think I can learn more than I would have in that math class all by myself. Today I had a shining example. I set out to understand why, and how a cosine matrix works on an intuitive level. I wanted to grok it. I think I understand finally. Instead of just being able to do the math I understand why it works. The next two things on my list are the cross product, and quaternion rotation.

Maybe I can actually start churning through the subjects like "Good Will Hunting" :-)

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Comments {9}

Re: girlfriend

from: puncher
date: Sep. 30th, 2004 10:06 am (UTC)
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There's a paradox with girlfriends (and a lot of things) which is something like:

You can't be dependent on them for happiness, but if you don't gain enough happiness from them, you'll end up not caring at all. It's a stupid balance, and one that I've never really gotten a hold of.

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snarble

Re: girlfriend

from: snarble
date: Sep. 30th, 2004 02:42 pm (UTC)
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have you seen heavenly creatures? each time I see your icon I think of that movie..

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Re: girlfriend

from: puncher
date: Sep. 30th, 2004 02:59 pm (UTC)
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I'm not sure that I have, now that I look at it- I always got it confused with something else. But I guess it has "The Third Man" in it? That image is from "The Third Man".

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Re: math

from: puncher
date: Sep. 30th, 2004 10:07 am (UTC)
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Cross product is pretty easy, but quaternions are a nightmare. I've recently gotten an OK grasp on them, so if you want help, let me know.

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Daniel Patrick Johnson

Re: math

from: teknotus
date: Sep. 30th, 2004 04:27 pm (UTC)
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Every year both high schools in Hillsboro had a balsa wood bridge building competition. There was a tendency for parents to get so interested in it that the parents would do more of the building, and design than the students. Not a fair thing considering the number of professional engineers in the area, so someone decided to have a second parallel competition at the same event with the same rules where everyone was allowed to play. Some aerospace engineers who built composite aircraft, and grew up building model planes out of balsa wood heard about the contest even though they didn't have any kids. They showed up, and dominated. The testing apparatus couldn't handle the forces involved. So my physics teacher invited them to class to talk about what they did. What stood out was how they calculated force vectors. "Well you can use sin, and cos, but we just used a ruler". My teachers jaw dropped. It was almost like I could hear it hit the floor. I don't remember if they proved their method was the same as using sin, and cos, but I know I could easily verify it today. That is what I mean by get an intuitive understanding. Know it well enough to deduce the mathematics language rather than simply memorizing the rules.

I think I understand how to use the cross product, and quaternions pretty well. I can follow proofs of their properties too. I have just felt like I am missing some fundamental understanding of them. Like I understand the proof that the cross product works, but I haven't understood how to derive it. So it is just little things like that I want to learn. I actually learned about how to use matrices from my book on quaternions. It has a lot of comparisons between the two methods so that you can understand when it is easier to use one or the other. It is a good way to learn I think. Matrices were actually developed after quaternions, and Cayley even extended quaternions to octonions, and sedonions in addition to being the first to develop matrices.

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snarble

(no subject)

from: snarble
date: Sep. 30th, 2004 02:54 pm (UTC)
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let's move to boston
I'll go to MIT and develop a british accent and you can develop anger management issues and sneak around solving complex equations/sweeping floors

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Daniel Patrick Johnson

(no subject)

from: teknotus
date: Sep. 30th, 2004 03:37 pm (UTC)
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I can sweep floors.

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snarble

(no subject)

from: snarble
date: Sep. 30th, 2004 04:25 pm (UTC)
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i put your number in my new phone
i named you danny dan and gave you a picture of a bunny

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Daniel Patrick Johnson

Phone directory

from: teknotus
date: Sep. 30th, 2004 04:29 pm (UTC)
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I'm a Bunny!

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