Teaching, Training, and Advising for the Harvard Mathematics Department. Oh, and some computer stuff.
Spotted at xkcd this morning:
Makes me think of my Math S-1ab students as I just gave them this classic problem on a midterm:
Show that there is a number c in between 0 and π/2 such that cos(c) = c.
technorati tags:funny, math, comic, xkcd
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I guess I’m lucky that my employer is a tourist attraction. Sometimes it’s mildly annoying to cross campus and be forced to walk in front of three groups taking pictures (as usually happens every lunchtime), but that comes with the territory. Sometimes the interaction is a little more memorable.
Yesterday I came to work at 9am and found the Science Center filled with tourists and their cameras. The lobby of the Science Center is nowhere near the most beautiful locale on campus, but it is open to the public. I found myself prevented from approaching the coffee stand by somebody videotaping a sign with a list of prices. (Literally: “Muffins: $1.79, Scones: $1.79″, etc.).
As I went to the elevator a family was taking pictures. The mother approached me and asked in broken English if I would take a picture with her. I said “sure”, assuming she meant of her and motioned for her husband to give me the camera. No, no, no, she gestured, she wanted her husband to take a picture of herself, her kids, and me. So some family is taking back home a souvenir of me, “an American,” complete with bike helmet, headphones, backpack and duffel bag.
I should have had him take one with my camera, too, and then I could have posted it here and you would have seen how funny it must have looked. Oh, well.
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Mac OS X cheerfully lets you know when new versions of its software are released. Usually this is a good thing. Even when you don’t need the update, sometimes it’s easier to go ahead and take it rather than be nagged by the reminder all the time.
Consider the latest (7.3) release of iTunes. it has new support for AppleTV and the iPhone. I have neither, but I figured I’d go ahead and update.
Suddenly, iTunes stopped working. Upon starting, it would read the library, present the browser window, but before I could click anything, it would crash. Here’s my (definitely not complete, and probably not optimized) flowchart for recovering from errors like this:
Step 1: Try again. This isn’t supposed to work. I mean, computers ought to be deterministic, so the same thing should happen every time you perform the same sequence of events. But some bugs really are ephemeral, and so sometimes just trying again does work.
Actually, I read a magazine article by a guy who tried to document exactly what he did every time he encountered a software error he didn’t expect. Almost every time, despite his better judgment and his self-observation, his first step was to try the same thing again Maybe it’s like reflexively saying “What”? when you didn’t quite hear what someone said.
Step 2: Standard Resetting and Maintenance. Some of these tasks are kind of like spells that you cast in hopes that they work. Someone I know worked in tech support for a year with absolutely no computer skills. The advice he most frequently gave (I guess the users had passed the “try again” step) was “reboot.” A clean reboot can get rid of stuff that’s happened since the last startup that’s getting in the way without you knowing it.
Regarding macs, I often see the advice to “repair disk permissions.” Not a bad idea. Another one people suggest is to force the periodic tasks:
$ sudo periodic daily
$ sudo periodic weekly
$ sudo periodic monthly
These are tasks your computer should be doing every day, week, and month anyway, and unless you’ve done something seriously wrong, they’ll succeed. They may not affect the problem, though.
A third option here is to get rid (or hide) preference files that might be corrupted. In ~/Library/Preferences there are lots of .plist, files which can get corrupted and prevent appliction launch. They have funny, java-style names like “com.apple.iTunes.plist” but you can usually recognize the problem application’s file. Trash it or move it to the Desktop and relaunch to let the application recreate it. If that works, you’ll have to restore the preferences you liked manually, but that’s usually better than not having the application at all.
None of this worked for iTunes 7.3 which is when I moved on to…
Step 3: Google. There are so many software support sites out there, whether for applications or operating systems, and so many users that you can be reasonablly assured that you’re not the first to have had this problem and hopefully somebody who’s gone before you figured it out. I googled “iTunes crashes” but I found a lot of stuff relating to old versions (and references to some of the spells above.” So be more specific: googling “iTunes 7.3 crashes” brings up pages on VersionTracker and MacUpdate about the problem. Apparently 7.3 is not ready for prime time. Good to know, but what now? That brings me to…
Step 0: Backup. (meaning, to duplicate)
Step 4: Back up. (meaning, to retreat) Luckily, I had backed up my hard drive this week. So I went and copied last week’s iTunes over the new one. Hey presto! back in time to a working iTunes version. And I’ll ignore the nag to update to 7.3 until I see 7.3.1.
What about Step 0? After advice from my sysadmin at work, I installed SuperDuper! a while ago. It makes a bootable copy of your hard drive. This means not only do you have a browsable backup to restore files and applications, you can restart using the backup (upon reboot, hold the option key, then select the backup drive). The pro version of SuperDuper! does incremental backups (a backup of all 80GB or whatever on your internal HD does take a long time), as well as a scheduler so you be reminded to do it periodically.
I have the tendency to not want to buy software, especially for something as easy as backup, which after all can be done pretty easily with a little unix. But think about it: if you lost your entire documents folder, with all your work, pictures, music, and everything, how much would you pay to get it back? It’s called insurance.
And if you need iTunes 7.2 yourself and don’t have a backup, I learned through MacUpdate that you can get it on Oldapps. God bless the web. 
technorati tags:itunes, backup, errors, crashes
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There’s a nice Math Problem on MetaFilter right now, inspired by an Arby’s promotion. If you can select five items from a set of eight, with repetitions allowed, for one price, how many possible meals can you eat? (The answer is 792).
It reminds me of a problem I put on the Math E-304 final this year:
Harvard Square has three restaurants that sell burritos: Qdoba, Felipé’s, and Boloco. I’ve decided to eat a burrito for lunch every day of the week. How many ways can I do that if:
- I have no preference how often I visit each restaurant?
- I want to eat at Felipé’s three times and Qdoba twice?
- I want to eat at each no more than twice?
Answers after the jump, if you want to try them.
(HT: 43 Folders)
I got my own digital camera to play with when I picked up the Nikon Coolpix L10 5MP on clearance (90 bucks!) at MicroCenter.
Partly this is for an article I’m writing about Web 2.0 and all the online photoservices (Flickr, Photobucket, Facebook) that are out there. I need some photos which aren’t of my kids to demonstrate with.
But a major reason is to upload this photo which I nominate for “nerdiest pop culture reference with a Brother labelmaker”:
The reference is to Office Space, which makes me happy to be in academia.
technorati tags:brother, stapler, funny, office, space
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