Vicki asks:

How do you figure out whether something is a prime number, whilst doing a test?

My method involves knowing some rules for working out factors, and (for small numbers) memorisation.

Firstly the small numbers: there are exactly 25 prime numbers below 100. This is a small enough set that I memorise them, namely:

Okay, I didn't strictly memorise all of them; when I was writing up the table, I was still working some of them in my head, using these rules:

• 2, 3, 5, 7, and 11 are prime. (5 numbers should be easier to remember than 25.)
• A number is a multiple of 2 if and only if it's even.
• A number is a multiple of 3 if and only if the sum of its decimal digits also is. (e.g., 87 is a multiple of 3 because its decimal digits, 8 and 7, add up to 15, a multiple of 3.)
• A number is a multiple of 5 if its last decimal digit is 5 or 0. Therefore, in terms of last decimal digits, the only ones you need consider are 1, 3, 7, 9.
• I don't remember a rule for working out multiples of 7, but I generally memorise them anyway. In particular, the products of 7 with 13, 17, 19, and 23 are 91, 119, 133, and 161. (These are the only special cases I know, not covered by the other rules.)
• Multiples of 11 below 100 have repeating decimal digits. In particular that means 11, 33, 77, and 99.
• For multiples of 11 between 100 and 200, the second digit is greater than the last digit by 1. In particular: 121, 143, and 187.
• The above rules cover all numbers up to 200, if you can memorise some square numbers. In particular, 49 and 169. (These are squares of 7 and 13 respectively, mentioned because the rules above don't cover them.)

Things get more complicated when dealing with numbers greater than 200. I'll write more about dealing with these later.

Finally got the Nokia C110 card on my sister's laptop to work (on Debian 3.0+backports.org). The setup is extremely silly.

1. The nokia_c110 module's Makefile doesn't have any accommodation for modversions. I had to cut and paste the CFLAGS from executing make modules.
2. The same module requires linking with a binary-only nokia_cs.a. This has external references to non-modversions symbols. I spent a couple of hours playing games with the linker before I discovered the --redefine-sym option to objcopy(1).
3. The same Makefile only updates /etc/pcmcia/config. This does no good when, for 2.4 kernels (on Debian at least), the file /etc/pcmcia/config-2.4 is used instead.
4. Saving grace: ifup(8) is called automatically. No fuss, no muss.
5. Pity that upon dissociation, retries do not seem to use the specified authentication key, with predictable results. The only way I've found to re-associate is to pull out the card and put it back in, though it's possible that I'm being a dork here.

ObDvorak news: At the moment I'm learning to ‘sight-read’ qwerty again. By that I mean I'm re-learning qwerty the same way as I initially learnt Dvorak: without the benefit of hunt-and-peck. Back when I was learning Dvorak, my keyboard was still in qwerty layout, so I had to learn which qwerty keys corresponded to which Dvorak keys. Now, having switched the keys around on my laptop, I'm learning to do the reverse. It'll be interesting to see if my qwerty speed will ever catch up to my current Dvorak speed, though my long-term intention is to use Dvorak whenever I can.

As some readers of haiku may know, one of my pieces was heavily inspired by Beethoven, in particular the Pathétique sonata.

Well, I'm very pleased to pick up a CD with this sonata, and some others, performed by Alfred Brendel (who in my opinion is a complete genius on the piano, especially in the performance of the first movement of Pathétique). I've been listening to this CD for days on end since I got it.

I've also been trying to play that sonata, with very mixed success. My fingers aren't anywhere near agile enough yet, and yet, and yet….

…at the risk of blowing my trumpet, I can type fairly fast, so it's not like I have clumsy fingers. Keeping in the theme of Dvorak typing, I am slowly trying to build my average typing speed up to 120 wpm if I can. Progress isn't too bad so far: for example,

Good, now I'm done with my ego trip! :-)

It seems that most everybody I correspond regularly with on Blurty has moved over to LiveJournal, so I'm not sure I'll find the opportunity to write here again. I'm trying to think of a new raison d'être for this journal, so that I have something to write.

I've been thinking a long time about starting a geek journal, so why not here? I could use it to talk about my upcoming programming projects, things I've been meaning to start long ago but never found the time to. The ideas are all in my head, and I still remember them with great clarity, but hopefully I can get around to them before I get RSI or something and can no longer type.

Speaking of which, the fear of RSI was a significant reason I decided to switch to Dvorak back in July last year (and all my entries since then have touched on this topic in some slight way). I've become fairly proficient at it, to the extent of reaching and sometimes bettering my old qwerty speed (about 70–80 wpm, though I never measured it back then).

Lately I've been doing typing speed tests on GNU Typist, and have found that I could type about 100–120 wpm when typing a sentence or two, and about 80–100 wpm when typing paragraphs. (In order to accurately time short sentences, I had to patch the program so that it counted the duration in microseconds.)

I'm fairly happy with the progress. The next step, now, is to bring my qwerty typing speed back to what it was, and maybe even improve it—without losing my Dvorak touch-typing speed. Right now, I can hunt-and-peck qwerty at about 25–30 wpm for paragraph-length text, and 40–50 wpm for sentences.

This way, I can relearn to type at a decent speed when using other people's computers, and still have a healthy typing habit when I'm at my own system. Besides, being able to touch-type two completely different keyboard layouts, and switch between them at will, should prove a great mental challenge. And every geek needs one. :-)

But while you're waiting, feel free to check out haiku, which has a great selection of user-contributed haiku. I post there once in a while, and hopefully more often these days.

I'm guilty as hell for not updating for half a year. Not nearly as guilty as not replying to Jen's email for a whole year, though. I wonder if she's still alive and well. If not, I'll just have to settle for shooting/drowning/hanging/poisoning myself, as she was one of very few people I felt I clicked with.

I just replied to her email. A year is a long time in which anything can happen, though….

In other news, I'm a fairly fluent Dvorak typist now. In a half-year's time, I think I might enter a typing contest or the like, if such a thing exists.

P.S. Dan and Kristin up a tree…congrats to you two! And Kristin, hope you enjoy your new life in the east coast!

…go to a certain Special K for birthday card and present, which have just arrived today (or yesterday, since it's now past midnight). I think Agatha Christie will be my bedtime reading for the next couple of nights…. You totally wock! :-) (That's not a typo; ‘r’ and ‘w’ are not adjacent keys, not even on Dvorak.)

Speaking of which, I've started using a typing tutor program called GNU Typist to help me learn to type faster. (I've never taken any formal typing training, and it took me several years—I frequently practised on a typewriter as a kid—to acquire my (qwerty) touch typing ability. I intend not to take several years to pick up Dvorak touch typing!)

The results have been promising so far. I am very pleased to have achieved this so soon:

Admittedly, this was a home-row exercise, but it seems to me a sign of good things to come! :-)

This post must have been written for you. :-)

In other news (apart from the Placebo gig, my birthday, &c), I am still going well on my Dvorak training after, what, two weeks. I still have some qwertyisms, but I now type half as fast as I did on qwerty, and I look forward to beating my qwerty speed soon!

(Sadly, I did not measure my qwerty typing speed prior to learning Dvorak, and I can't type in qwerty quite as quickly anymore—lots of Dvorakisms showed up when I tried. Frankly, I can see why some say that after you switch to Dvorak, you'll be really reluctant to type on qwerty again!)

I started playing with the Dvorak keyboard layout today (as opposed to qwerty, which most systems use), just as a mental challenge (and the promise that, once I become familiar with it, I can type faster with it than with qwerty).

Until then, people who IM me are advised to be patient; I may type up to ten times slower. :-)

I'll be writing a survey myself tonight (if I have time), so watch for that too…. But the current one is snarfed from unspokenthought:

In the last two days
The haiku community
Filled with excitement

As two, then some more
Members contributed to
‘Innocuous’ talk

Or not; you decide!
Start at the 20th where
All the fun began

In the past, I feel that I'm getting logged out on Blurty more often than I should be. (I use the ‘never expire’ type of login, so that's what it should be.) The only theory I have on this is that somebody else has my password and is logging in under this account. (I have even more reasons to believe this theory; ask me if you want the technical details.)

So, I've changed my password. Please let me know if you've seen any odd comments posted by my user!

I wish there is a way to actually check which IP address a person logged in under…not that it would be useful on Blurty, since you can still spoof your IP address by setting X-Forwarded-For. (This is easy to fix. If Blurty admins are interested, I'll be happy to provide a patch.)

I've just finished reading The Summerhouse by Jude Deveraux, and I really like it. It's the first romance I've read that invites the reader's introspection (and Special K tells me that this is a common trait among Deveraux's books, so it looks like she'll become one of my favourite authors). I've spent much time thinking about why each heroine made the choices she did, and the significance of their situations and choices. Here's what I've come up with.

(Note that the rest of the article are all spoiler material. If you intend to read the book, then don't continue reading this article until you've finished the book.)

In conclusion, I really like the story. It is much more interactive than most of the novels I've read: not in the sense of directing the characters, as one would when partaking in interactive fiction, but in the way that the story revolves around a theme that many readers care deeply about, and encourages them to speculate on what they'd do were they in the heroines' shoes.

Yes, I finally got around to replacing my userpics. They look vaguely the same as before—still the OpenBSD blowfish images—but completely redone from the source images. The main difference is that they are no longer restricted to 256 colours, and use the alpha channel (so if your browser supports it, the images should show up with nice smooth edges).

I also took the time to place a proper(ish) copyright message on the images. And since the PNG format is nice enough to allow people to put in other string types, I've also decided to credit ImageMagick as the tool I used to make the images. ( Unlike my original set )

Filched from girl_friday.

First, I should mention that I'm glad that they've started enforcing the 18+ rule. It will make Blurty a more comfortable place in the long run.

But two things still worry me: how do they determine whether users lie about their age, and what is going to happen with the 200000 or so early adopter accounts, most of which are underage? Blurty is not seriously going to be a better place until the adult-to-child ratio rises steeply. But at least it's a good start, and I applaud Blurty administration for taking this step.

If anything, it means I now have more time to get Spillville working right, rather than making the site just a place for Blurty refugees. I have so much work at present that I won't really have free time for the next three weeks (and of course, as people can tell by my lack of updates, I've been very busy the last month or two as well). But yes, I do intend to roll out the site. If anything, it will have a better maturity ratio than Blurty will have for a long time. :-)

…I might start turning into a David Bowie groupie (well, not quite, but you get the idea). The more I listen to David Bowie's music, the more impressed I am. Currently I'm listening to the Let's Dance album. It's full of goodies!

If you were at a karaoke party, and in the sole company of your friends or otherwise in a setting where you have no need to be self-conscious (and would therefore have no problems participating), which song would be your first choice?

View Answers

This is a little exercise I cooked up over the last few days, in which I describe how I met the various people who are on my Blurty friends list. Since there are only 9 such people so far, it's not a difficult task at all. :-)

• allyex: through nightvixen
• dsavage: through nightvixen
• emptyskies: long-time LiveJournal friend; have since met in real life
• girl_friday: from comment in my journal
• lilsinsual: over_18yrs membership application
• nightvixen: long-time LiveJournal friend; have since met in real life
• rachelslivecam: through nightvixen
• wickedjealous: from comment in my journal
• yuan: from comment in thecoffeehouse

I've finally taken the plunge and moved my personal website from my home computer to the Spillville machine. With the instability of my home internet connection last night, the last thing I want is for my website to be inaccessible.

I've updated the DNS information today, so people using my randomly-selected over18 image may notice that they'll be hitting a different machine. :-)

Anyway, if you have your own web site, feel free to post its link and I'll check it out on Netcraft! It's interesting to see what sort of software people run on their web servers. For example, both LiveJournal and Blurty use Linux, whereas uJournal uses FreeBSD.

Oh wait, there is! That's right, my LiveJournal friend Nick from Melbourne ('cuz I refuse to accept that he's in fact moved to another town) has finally got a Blurty! Feel free to make him feel at home. :-)

In other news, my DSL connection at home is sucking arse today. If this continues for much longer, I think I'd have to switch back to dialup. Oh, the horror!