lardbucket: blog

So, as I just spent a half hour fixing friends’ blogs after the upgrade to WordPress 2.9, perhaps this will help someone else if it gets indexed by the search engines:

We were having problems with WordPress thinking that it was accepting uploads of images and trying to display them, but the files didn’t actually exist where they should have, throwing a file not found in the browser. It was a bit weird, because the only errors in the server log were that the browser couldn’t find the file, but the AJAX image editor in WordPress seemed to work. It turns out that somehow the settings got changed. If you’re having the same problem, follow these steps:

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If you’re old enough (well, not that old), odds are that you watched this live, or at some point. In what, as far as I can tell, was the first human non-terrestrial Christmas greeting, Frank Borman, Jim Lovell, and William Anders, after noting the lonely view below, read off Genesis 1:1-10, then,

“And from the crew of Apollo 8, we close with good night, good luck, a Merry Christmas, and God bless all of you – all of you on the good Earth.”

And, of course, for anyone who has been persuaded otherwise, just under three hours later, after performing the Trans-Earth Injection on the far side of the moon, Lovell reported back, “Please be informed, there is a Santa Claus.” (Houston / Mattingly accepted the information, saying, “That’s affirmative. You’re the best ones to know.”)

So, the CS232 spimbot competition was today. My partner (Connor Simmons) and I made a robot (actually just a piece of code) that came in second out of 37 (or 38?). It was a rather interesting competition. The page on it that I’ve set up (complete with MIT-licensed source code) is right here.

I remain impressed by the only team to beat us (and their come-from-behind win), whose inventive approach used an attack on the time-based seed of the random number generator to find where the tokens could be placed within the 50 minutes the competition was run. The one-second resolution used as a seed for the random number generator gave a small enough number of possible locations for tokens that they were able to accurately predict where all the tokens would be given just one token’s location. This strategy meant they lost a number of matches (I assume to slow calculations, but I may be wrong), including to our robot, but in the end, they were able to win more often (or by more tokens), so congratulations to them.

Andy Schmitz

The Illinois Certification Testing System’s Basic Skills Test is required for admission to any secondary education (high school, middle school) teaching program in Illinois. (Notably, I’m taking it today.) It has 126 questions:

• 48 Reading Comprehension Questions
• 42 Language Arts Questions
• 35 Mathematics Questions
• 1 Writing Assignment

So, nearly everyone taking the test has also taken the ACT (required in Illinois for high school graduation in most cases). On the ACT, these sets should take:

• 48 Reading Questions – 42 minutes (48 questions * (35 minutes / 40 questions)) [reference]
• 42 Language Arts [English] Questions – 25.2 minutes (42 questions * (45 minutes / 75 questions)) [reference]
• 35 Mathematics Questions – 35 minutes (35 questions * (60 minutes / 60 questions)) [reference]
• 1 Writing Assignment – 30 minutes [reference]

And yes, they’re about the same difficulty (see: PDF list of tested skills for ICTS Basic Skills Test and the ACT). Having looked through the materials for both, I’d put the ICTS Basic Skills Test somewhere around the middle of the ACT’s level of questions, if a bit toward the higher end in some cases. (I looked mainly at the math questions, but the same seemed to hold for the reading and English questions as well).

So, that’s about 132.2 minutes. So, just over two hours. Say 2.5. Except the ICTS Basic Skills Test gives twice that. 5 hours. To answer 125 questions and write a short (five-paragraph is fine) essay. That just seems wrong. And the Basic Skills Test also allows the person taking it to skip around in the sections as much as they like (so there’s no lost time in waiting for a section to end, which is effectively expected in the ACT).

(Notably, the ACT’s “Services for Students with Disabilities” gives time-and-a-half testing as their standard extended time solution. The Basic Skills Test default is more than time-and-a-half, and also allows time extensions for test takers with disabilities.)

Somehow, it seems as though the Basic Skills Test doesn’t really do anything. It’s effectively “easier” than the ACT for most (all?) students who got into a college, so adding it as a requirement makes little sense. A “passing” Basic Skills Test is 240 out of a scaled 100-300 score, with lower minimum requirements on each section.  It’s unlikely to be scaled in the same way the ACT test is (which actually is scaled from 1-36 as far as I can tell, although few students score below an 11), but if it were, that would be equivalent to roughly a 24 on the ACT, assuming a quick Google calculation was correct. However, I would also say it’s easier to do well on the basic skills test, with the extra time and fewer types of questions, not to mention at least an extra year of knowledge.

Does anyone else see any value in this? I assume (but haven’t verified) that there are additional qualifications once one wants to actually get certified to teach (rather than simply to learn how to), so is there any reason for this requirement? I’m also not particularly happy that the website for such a supposedly impartial (and necessary) test is listed as “Copyright © 2009 Pearson Education, Inc. or its affiliate(s).”

Andy Schmitz

Time

For some reason my computer’s clock got set a good 12 minutes ahead. I’m not exactly sure why, but it appears to have happened around a restart, perhaps due to a hardware clock that’s off, and the NTP daemon didn’t correct it. To manually reset the time based on a time server in Ubuntu, run

sudo /etc/init.d/ntp stop
sudo ntpdate ntp.ubuntu.com
sudo /etc/init.d/ntp start

If you don’t stop the NTP daemon first, you’ll get “ntpdate[pid]: the NTP socket is in use, exiting”. Notably, don’t do this in a cron job, as ntpd should be enough. (It’s not clear why ntpd didn’t resolve the issue in the first place, but I’m blaming that on some configuration bug.)

BOINC and Time

BOINC seems to have had a bit of a problem with the time shift. (It was normally set at 80% usage, and jumped to 100% with absurd remaining times.) That turns out to be pretty easy to fix:

sudo /etc/init.d/boinc-client restart

And it should be good to go. It may still have some strange estimates for time (it would likely be safer to stop boinc-client before updating the time and then start it afterward, if I realized that would be an issue), but that’ll be fixed after the current workunits complete.

USPS Tracking

If you have a label number for a USPS package you want to track, you can bookmark this URL (obviously, put your number at the end) or keep it open in a tab. It’s not the result of a form submission, so refreshing won’t prompt for a resubmit, and loading the page again won’t ask for the tracking number.

http://trkcnfrm1.smi.usps.com/PTSInternetWeb/InterLabelInquiry.do?origTrackNum=[Your tracking number]

Yesterday, GraphSketch passed over 30,000 graphs rendered. That’s quite a few. Thanks to everyone for making it so popular.

It also seemed like a good time to release something I’ve been working on smoothing out for the past few weeks:

Yep, you can now graph parametric equations. Just head over to http://graphsketch.com/parametric (or click the “Parametric”mode just above the equations on the main GraphSketch page).

To keep things simple, you can only graph three parametric sets of equations at the same time. You can choose the range for t, and it defaults to a reasonable -10 to 10.

Also, while I was updating the website, I made the text a bit smaller (about the difference of going from a 12pt font to a 10pt font) and added a (hopefully unobtrusive) section pointing out the availability of posters, should anyone be interested. Polar graphing should come soon, hopefully, but it is somewhat possible using parametric equations by setting x=r*cos(t) and y=r*sin(t), too.

Andy Schmitz

A number of you who know me in real life have probably seen a number of my posters. Three of them currently adorn my dorm room. I had been offering them to friends I knew, but not to everyone, because I hadn’t gotten around to it. But that has changed now, with posters.lardbucket.org.

The website itself is (purposely) a bit sparse, but it will let you browse the four existing posters, and grab one for yourself from Zazzle at fairly reasonable prices. (I really only make a few dollars from each one, depending on size.) Other than taking a while to ship, Zazzle’s processing has been fairly good, and the three large prints I have from them are reasonably high quality, even on their “basic poster” paper.

Each of the posters on posters.lardbucket.org was created by me, using a reasonably high-powered computer to do the rendering. Each of the posters is a mathematically-defined rendering, and could theoretically be rendered at any size and not lose any detail. Therefore, the large posters are still high quality images.

So, if you’d like to get a neat-looking poster and send a few dollars my way at the same time, have a look at posters.lardbucket.org.

Thanks,
Andy Schmitz

A few notes on setting up PvPGN (the continuation of bnetd) for a private LAN. (The reason I’m setting it up is that I don’t expect to have an Internet connection for connecting to Battle.net proper, and would like to have the capabilities it provides, especially ladder games.) This post is generally much more technical than most of my previous posts, so you may want to skip it if you’re not really sure what’s going on. You won’t miss much.

So, my setup involves a router with DD-WRT, and an OLPC XO. The XO is set up using Ubuntu Intrepid on an SD card.

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In under three weeks since it was launched, GraphSketch has now been used to create (over) 10,000 graphs. It also has had over 3,500 visitors, coming from every continent except Antarctica, though many visitors haven’t graphed anything (and many visitors have graphed far more than average). Work on new features (parametric and polar graphing, among others) will likely resume after school is over, as I still have three finals remaining, and am now off to continue studying for a math final.

At any rate, thanks to everyone who has promoted GraphSketch in one place or another for making it so successful.

Andy Schmitz

P.S. If you have any suggestions for GraphSketch itself, the original post on it is still probably the best place to leave them, as I’ll check back there for ideas when I’m working on it. Thanks!

So, I spent the last few days working on GraphSketch, a new, free, online grapher. It’s available at http://graphsketch.com/ . Go check it out for a minute. Try graphing something like “(x-3)(x+10)(x-14)/100” or “tan(pi*x/10)“. I’ll wait.

Done? That’s pretty much it: Enter an equation, choose some settings, and graph it. There are a number of functions you can use to plot, you can save the graphs to use later (in documents, worksheets, etc.), you can create a permanent link to them to share with others, and a few other nice little things (like getting a quick graph by going to an address like http://graphsketch.com/sqrt(x) ). Details on how below.

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