Author: Rory

Damn scientists can’t stop meddling with the natural order of things. The recently engineered blue rose has just ruined a perfectly good Valentine’s Day poem. On the plus side they look incredible.

I just glanced at RTÉ‘s story on the death of Terri Schiavo. The Pope’s opinion on the removal of her feeding tube is mentioned before the United States congress’s. Presumably because he had so much to do with the case. Maybe he’s just speaking out in favour of leaving in feeding tubes in general.

This being the last week of my holidays I’ve tried to get myself back into a socially-acceptable schedule. Today I was out of bed by one o’clock. After a lazy two hours catching up with everything that’s new on the Internet, or perhaps just that small part of it that holds some interest, it’s time to get to work on my project. Incidentally, as I alluded to on Sunday, I’m able to work from home now. Who knows what they fixed, and frankly who cares. It saves me three hours a day of commuting.

I can’t start to work on an empty stomach and it’s past three o’clock so it’s time for breakfast. By now the cynics in the audience are sarcasticly saying to themselves "I wonder will he find something that makes it difficult to start work on his project?" You have no idea. Is it a task that requires my attention before anything else? Is it a family member asking for help? Is it some distraction from which I cannot tear myself? Try The Simpsons season 5 on DVD. Damn you foul temptress!

I’m hoping not to hear a lot more news about today’s earthquake in Indonesia, on the grounds that no news is good news. Quite frankly, the less newsworthy this turns out to be the better. About half an hour after the event I hit on Sky News’ live coverage. They were talking about a magnitude 8.2 quake, as reported by the US Geological Survey. A few minutes later they mentioned the Associated Press report saying it was an 8.5. I think that was attributed to a Japanese meteorological organisation. A glance at Google News tells me it’s up to 8.7 now. Thankfully there’s no news (and that’s good news, remember) of a tsunami, and the death toll seems reasonably low (though it’s about 300 more than any of us wants it to be).

So in the welcome absence of additional news I figured I’d write up a brief note on the Richter magnitude scale. I thought this would be a good idea to mention when the Sky newscaster said that 8.2 isn’t much less than 9.0 (the eventual magnitude of the December quake). It is. In fact it’s over six times less or, if you prefer, it’s less than one sixth as big. The Richter scale is a logarithmic scale, so 2.0 is ten times 1.0, 3.0 is ten times 2.0, and so on. Now here’s a mistake I’ve seen with logarithms too many times to count. If 2.0 is ten times 1.0, then 1.5 is not five times 1.0. How do you figure out how much bigger 1.5 is than 1.0? Read on.

2.0 is ten times 1.0 because 10² (ten to the power of two, equal to a hundred) is tens time 10¹ (ten to the power of one, equal to ten). So 1.5 is 10^1.5 ÷ 10¹ or 3.2 times 1.0 on a logarithmic scale. That makes sense because 2.0 is also 3.2 times 1.5. So 2.0 is 3.2 x 3.2 = 10 times 1.0. Knowing all of this, how much bigger is a 9.0 quake than an 8.2? The same calculation (10^9.0 ÷ 10^8.2) gives us a factor of about 6.3. Note that 9.0 ÷ 8.2 is less than 1.1 so if it was a linear scale they’d be pretty much the same quake.

This large increase in size (or strength, or whatever you want to call it) with a small increase in magnitude is what lets us use the same scale to cover all earthquakes from the tiniest un-noticable tremor to the biggest quake ever recorded (Chile in 1960). The same principle is applied to sound using the decibel scale in which an increase of ten decibels is an tenfold increase in sound energy, and to the size and brightness of stars.

Of course the huge increase in strength with magnitude also means that the change in estimates of the magnitude of today’s quake from 8.2 to 8.7 represents a threefold increase in estimated strength. I continue to hope it doesn’t get revised any farther upwards. Ditto for the death toll, which stands at just under 300 as I write this.

Via Neil Gaiman (yes, that Neil Gaiman), the least appropriate logo in the world. Sometimes you really have to look at your design from more than one angle.

I’ve spent the last few weeks working on my major project and I anticipate spending the next two weeks doing the same. You probably knew that because of all the bitching I’ve been doing about not being able to work on it from home. That’s a problem which may actually have been fixed now; more on that later. I only bring it up now because it seems that ever since I started this project, a Web application, I’ve become acutely aware of aspects of SoylentRed that need to be updated, fixed, removed, or (re-)implemented. Since I can’t justify working on a hobby application when there’s 30% of my overall grade for this whole course waiting to be earned I’ve ignored those little SoylentRed annoyances for the most part.

I did add a link to the comments in the Atom entries, and I added text to the toggle-comments and add-a-comment links. This may or may not have been an attempt to encourage people to leave comments. I figured the links weren’t visible enough as they were. I seriously have no clue who those anonymous Bloglines subscribers are; if you feel like de-lurking for 30 seconds I’d really like to hear from you.

Anyway, I thought I’d suggest a few of the changes I’d like to make. Maybe I’ll get some feedback. Maybe no-one cares. At the very least it will mean I won’t forget about it all. I’ll start with the visuals. I’m not good at graphics. I try occasionally; I succeed even more occasionally. I would like SoylentRed’s design to be a little better; at the very least to have a header graphic or something. I think the colours could do with a little tweaking too. I may be ever-so-slightly humbled by the fact that half of my blogroll is made up of world-class designers.

Next up, though it’s undoubtedly more important than pretty graphics, is an intuitive user interface. Three things annoy me right now. Entry titles should be permalinks. That’s just how blogs seem to have developed. There are enough people out there on the Web that have seen enough blogs with permalinks in titles that it’s an expected behaviour. It’s not okay not to live up to that expectation. Ditto for the main site header linking to the main page. That’s a Web-wide requirement. Like animated "under construction" icons it’s ubiquitous in this medium. Unlike those icons it serves a useful purpose. Finally, have you ever found yourself at the end of a list of comments wondering where the add comment button was? Here’s a clue: it’s above the comments. Now go find something heavy to hit me with for when I thought up that placement.

A quick reshuffle of the top-level navigation wouldn’t go astray, unlike anyone who tries to use it. The projects link is given far too much prominence considering the fact that it conceals a single barely-supported out-of-development experimental project. That section needs to be expanded or dropped. The atom link just confuses casual visitors. I plan to move it to a new home elsewhere in the sidebar where it will enjoy a peaceful existence surrounded by explanatory text.

Regarding new features you might spend some of the coming weeks (and months, and perhaps years…) looking forward to the addition of individualised Atom feeds for keeping track of comments. Each person gets a feed consisting of comments made to threads that they’ve commented in. That concept is shamelessly ripped from A musing or too much? Throw in optional email notification of replies, a main page list of recent comments, and the ability to store your data in a cookie when you comment, and I’m up to about a 1999 level of user interaction.

How much of this will actually get done is as much a mystery to me as it is to you. I’ve made lists like this before that aren’t finished. I’ll get some of it done before I get distracted something new and shiny. That’s the thing with works-in-progress. They’re never finished.

A couple of weeks ago I claimed on rec.juggling that there’s no such juggling pattern as a three-ball synchronous half shower. I was contradicted by a long time rec.juggling regular named Luke Burrage. His exact words were:

You are so wrong it hurts. I’ve just tried it and managed to juggle a three ball synchronous half shower on my first attempt.

Just because you can’t make the numbers add up using siteswap doesn’t mean that the trick isn’t possible.

Well that’s quite an assertion to try to contradict, but I like a challenge so here follows an explanation of why there’s no such trick as a three-ball synchronous half shower. For the benefit of non-jugglers I’ll describe all of the jargon you need. It’s actually very simple.

Jargon

Siteswap

Siteswap is a system of notation for juggling patterns. I’m not going to describe it here since there’s no need for it when describing the patterns I’ll refer to.

Shower

A pattern where one hand does all of the throwing and the other does all of the catching. The catching hand just passes the balls to the throwing hand after each catch. The balls follow a high arc from one hand to the other and a quick low pass back to the initial hand.

Half Shower

A pattern where the balls thrown from one hand always go higher than those from the other hand. The balls follow a high arc from one hand to the other and a lower arc back to the initial hand.

Synchronous and Asynchronous

Synchronous patterns have both hands throwing at the same time. Asynchronous patterns have the hands throwing one after the other in alternation.

That’s all of the juggling jargon you need to understand this post. If you got this far you should be able to understand my point.

Luke’s Three-Ball Synchronous Half Shower

Luke claimed that he could "juggle a three ball synchronous half shower on [his] first attempt." He wasn’t lying, he really did juggle a pattern that looks like a good candidate for the three-ball synchronous half shower. If I’m going to claim that it’s not one, I’m going to have to describe what he did.

Take two balls in the left hand, one in the right. Remember this is a synchronous pattern so both hands will throw at the same time. The left hand throws in a low arc to the right; the right hand throws in a higher arc to the left. That’s the gist of half shower. One low arc, one high. When the left-thrown ball lands in the right hand the right-thrown ball should be at the peak of its arc. We still have the last ball in the left hand. So make the same throws again. Low arc from left, high arc from right. This time when the second left-thrown ball lands in the right hand the first right-thrown ball will land in the left. Continue ad nauseum.

So what’s the deal? It’s a three-ball pattern, it’ synchronous, it has the distinctive high arc and low arc of a half shower. Why is this not a three-ball synchronous half-shower?

Why Luke’s Pattern Isn’t a Half Shower

Look at the descriptions of shower and half-shower patterns again. Shower: "The balls follow a high arc from one hand to the other and a quick low pass back to the initial hand." Half shower: "The balls follow a high arc from one hand to the other and a lower arc back to the initial hand." Now let me let you in on some elementary ballistics. A pass is still a parabola. It’s an arc, just like the low arc in the half shower. The descriptions I’ve given so far, the descriptions that most jugglers would recognise as distinguishing a half shower from a full shower, are meaningless. They do not distinguish. They are, in fact, qualitatively identical.

There is a qualitative difference between the shower and half shower in three-ball asynchronous and in all higher numbers. Maybe the people juggling the patterns don’t know what it is, but it’s there. In a three-ball asynchronous shower the low throw (the pass) is thrown and the next throw from the other hand is that passed ball. In the three-ball asynchronous half shower the low throw is thrown and the next throw from the other hand is a different ball. The same applies to higher numbers. In all cases the shower is identified as the pattern where the low throw is followed immediately by another throw of the same ball. The half shower always has another throw in between.

Look at Luke’s pattern again. The low throw is thrown again as (part of) the next throw. By the only definition that qualitatively distinguishes showers and half showers this pattern is a shower. It’s the three-ball synchronous shower.

Now to be fair I will acknowledge that many people will still prefer the high arc/low arc and high arc/pass descriptions of half shower and shower respectively to the other-ball-in-between and same-ball-thrown-again descriptions. And of course it usually doesn’t matter because this is the only case where they differ. I am consequently not likely to jump down someone’s throat for claiming that the three-ball synch shower and three-ball synch half shower are different. On the other hand I think I’ve made a good enough argument that the claim "You are so wrong it hurts" could be described as, at the very least, embarrassingly exaggerated.

This nifty piece of obfuscated C was mentioned in a recent Slashdot thread. It’ arranged to spell the word "maze"; it is itself a valid maze, with the "–" decrement operators acting as the entrance and exit; and when compiled with gcc’s -fwritable-strings option it will generate a maze of any length. People with this much time on their hands deserve our respect.

char*M,A,Z,E=40,J[40],T[40];main(C){for(*J=A=scanf(M="%d",&C);
--            E;             J[              E]             =T
[E   ]=  E)   printf("._");  for(;(A-=Z=!Z)  ||  (printf("\n|"
)    ,   A    =              39              ,C             --
)    ;   Z    ||    printf   (M   ))M[Z]=Z[A-(E   =A[J-Z])&&!C
&    A   ==             T[                                  A]
|6<<27<rand()||!C&!Z?J[T[E]=T[A]]=E,J[T[A]=A-Z]=A,"_.":" |"];}

Via Stuart Langridge, someone named Neil K—though I assume his real name is longer than simply ‘K’—has created an interesting series of photos each composed of 50 randomly-chosen images on a certain theme blended together. It’s all done programatically. As he says, "No human is involved in choosing, positioning, or blending the images." Some of the results are very cool looking, particularly the few that have some ghostly vestige of one of their more striking component images (try flower and soup for example).

It rained on me on my way to college. A lot. I got here to discover that I can finally access the server I need to test my project code, but netsoc’s FTP server is down. Guess where I was keeping the code I’ve been (blindly) working on for the last four days?