Tuesday 29 Jul 2014 comment? I'll start with what I liked about the movie Boyhood. It's not overdone, it was a risky project to undertake, and it has some poignant, thoughtful moments. And yet I was nowhere near as taken with it as was pretty much every critic. It's a movie about the plainness of life, and I'm a tough customer for such stories. That's not to say I can't appreciate them, just that the style and tone are going to have to carry the day. And indeed a lot of people are delighted with the tone of Boyhood; I just wasn't one of them. IMDB quotes director/writer Richard Linklater as having said, Most of us are losers most of the time, if you think about it. To the extent I get his point, it doesn't necessarily translate into my wanting to watch losers on screen. I find Linklater an OK director but not much of a writer. There's a scene in Boyhood where the father picks a less-than-optimal time and place to talk to his teenage kids about contraception. The daughter cringes. I found that one of the stronger scenes in the movie, but even so it's still quite plain. I've witnessed awkward parent-child interaction that put it to shame and I'll quote it here now. The setting was a bunch of us out climbing, including a married couple and their 16-year-old son.
Boyhood has no dialogue that perfect. Tuesday 22 Jul 2014 comment? On September 1, 1983, the Soviet Union shot down Korean Air Flight 007 which had violated its airspace. The USA was quick to insist that the Soviets had fired on the plane with full knowledge that it was a civilian airliner. But we didn't know that. From the introduction to Seymour Hersh's book on KE007, The Target is Destroyed: Those [intelligence agents] who chose to talk to me did so out of a conviction that political abuse of communications intelligence has become a reality in the Reagan administration, and a belief that to protest to their superiors about it would be futile and damaging to their careers. Some of those interviewed did retire from intelligence service shortly after the events described in this book. In a few cases, the mishandling of Flight 007 played a role in their decision to get out.The USSR in turn claimed the flight had been deliberately sent into Soviet airspace at the request of the USA. That assertion was also ahead of any available evidence. Five years later, the USS Vincennes shot down Iran Air Flight 655. Statements by US officials featured numerous untruths, e.g.:
Thursday 17 Jul 2014 1 comment Today, math (but nothing scarier than matrix multiplication and a whiff of complex arithmetic). When I first did photography, scaling an image was done by moving an enlarger head up and down and mirroring an image was a matter of turning the negative over. In computer graphics, scaling and mirroring are mathematical transformations: (x,y) coördinates of image elements are replaced by linear combinations of the original x and y. Matrix multiplication is a concise way to express linear combinations:
A key feature of using matrices is that multiple transformations in sequence can be folded together by matrix multiplication. Sometimes a sequence of transformations turns out to be equivalent to a single familiar transformation. A carefully-chosen sequence of three shears is equivalent to rotation, good to know if for some reason you must do arbitrary rotations with a feeble program like Micros‑‑t Paint (which only rotates by multiples of 90° but which does know how to shear). But matrices aren't just for graphics. The Fibonacci sequence (0, 1, 1, 2, 3, 5, 8, ...) has the recurrence relation Fn = Fn‑1 + Fn‑2, concisely expressible by powers of a 2×2 matrix: Raising a matrix to a power by repeated matrix multiplication is a slow process, but in this case there's a trick loosely akin to the rotation-by-three-shears maneuver. There's an advantageous way to decompose this 0 1 1 1 matrix into three factors. In the language of graphical transformations, the three components are a rotation (by about 211.7°), then a scale-with-reflection, then the inverse of the original rotation. Denoting the appropriate rotation matrix by R: And because raising a matrix to non‑integral powers is even more fun than doing arbitrary rotations in Paint, why not calculate Fn for continuous real values of n? The negative number ‑0.618... in the diagonal matrix means the results are complex, but that just adds to the flavor. Here's Fn plotted on the complex plane as n varies from [0,7]. The curve intersects the real axis at Fibonacci numbers 0, 1, 1, 2, 3, 5, 8, 13. Thanks to everyone whose pages are linked to above and to Ron Knott, on whose page I first saw Fn evaluated for continuous values of n. Tuesday 01 Jul 2014 comment?
Philosophy is to science as pornography is to sex: it is cheaper, easier, and some people prefer it. |
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