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:

1. Go to the WordPress Dashboard (your administration panel, where you can create new posts, etc.)
2. Click “Settings” on the sidebar.
3. Choose “Miscellaneous” as a subcategory.
4. Change “Store uploads in this folder” to something correct for your server. In general, this should be “wp-content/uploads”, which is supposedly the default.

And that’s it. Image/media uploads will work again.

Andy Schmitz

(It’s not clear whether the problem was triggered by the upgrade to 2.9 or had existed for some time, but from reports that image uploading worked recently, I’m inclined to think it may indeed have been the automatic upgrade to 2.9 that caused the problems.)

“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.”)

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

• 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

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]

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

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

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.

XO: Installed packages “build-essential”, “libz-dev”, and “cmake”. Grabbed the latest development snapshot of PvPGN (1.99 r521), and compiled it using cmake, make, sudo make install. Configuration gets installed in /usr/local/etc, other files in /usr/local/var. The PvPGN support files (also available from their download website) need to be extracted into /usr/local/var/files. Also from /usr/local/var/files, use bnftp to grab the relevant update files for the latest version. Edit /usr/local/etc/bnetd.conf to satisfaction. I also ran “chmod -R a+w /usr/local/var” and “chmod -R a+w /usr/local/etc”, though it’s likely that only the former is necessary, and not even that if you tune users properly. This was more of a quick hack than something I’d use for a long-term server. I grabbed the newest autoupdate.conf and versioncheck.conf files from the PvPGN CVS server, and uncommented the links to the files I’d downloaded in autoupdate.conf. I also found that for the StarCraft entries, I needed to create one without the version number extension, to allow earlier versions of StarCraft to update (for some reason, it wasn’t being caught by versioncheck.conf, even after I uncommented the right sections). That meant adding a line like “IX86    STAR    STAR        STAR_IX86_1xx_1161.mpq” to autoupdate.conf. Watch out for duplicate instructions for the same version but different updates though, I’m not sure what that could do. (This last portion was only useful because I am redirecting the pre-patch battle.net server to PvPGN, and wouldn’t help most people.)

Router: Set up fairly trivial wireless encryption, mainly to make it clear that the AP isn’t useful to most people. Added a static lease to dhcpd under DD-WRT’s Services menu, giving the XO a fixed IP address outside the standard DHCP address range (by MAC address). Enabled dnsmasq to let me redirect battle.net domains, adding the lines “address=/europe.battle.net/192.168.1.50″ and “address=/exodus.battle.net/192.168.1.50″ to the dnsmasq configuration options, redirecting the Europe Battle.net server to my XO, as well as pointing the default pre-patching server (for StarCraft, anyway) to the same location. (The other battle.net subdomains are uswest, useast, and asia.) For some reason, “Apply Settings” didn’t work for me, but “Reboot Router” after applying the settings did work.

Clients: Nothing here was necessary, but I did perform a few tests. Things worked almost immediately. Automatic updates worked fine, even from unpatched installs (of StarCraft 1.05), after adding the lines above to autoupdate.conf.

So, it should work reasonably well. I don’t feel bad about redirecting the battle.net domains, because nobody would be using the router without knowing that was the case. It’s also not really allowing illegal copies of the games, because I can make sure there’s a legitimate copy of the game for everyone connecting to the router when I give out the encryption keys. Overall, it should work out reasonably well. The one thing I’m not thrilled about is the fact that the Marvell Wi-Fi  drivers on the XO don’t seem to support Master (AP) mode. If that were the case, I could have the PvPGN server and router on one laptop, and not even need power at all, but unfortunately, that doesn’t seem like it will work at the moment.

Andy

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!

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.

GraphSketch is mostly written in PHP, with the actual graphing done in gnuplot. Some manipulation is done in PHP before things are passed to gnuplot to account for odd roots, implicit multiplication, and so forth. In gnuplot, I’m using the pngcairo terminal, implemented in the not-yet-released gnuplot 4.3 CVS code (it’s public but not a “stable” release), to get anti-aliased graphs, because aliased graphs (especially with low graph widths) tend to look relatively poor.

Programming and debugging for the first version took just a few days, which was relatively quick compared to other such applications I’ve made. The main interface is almost entirely one PHP file along with some JavaScript that uses prototype and script.aculo.us to make things work smoothly. Automatically preloaded graphs like the link above are handled through a relatively simple mod_rewrite rule. Naming and the domain name were debated among a few people and decided upon in under an hour, which was also pretty quick.

So, if you have any questions, comments, or suggestions about GraphSketch, feel free to leave a comment below or email me at andy.schmitz at gmail.com.

Thanks,
Andy Schmitz

Update 05/12: GraphSketch now has delivered over 10,000 graphs.