Comments for Dave's Archives

Comment on Please reboot the aircraft by Wilson Waters

Wilson Waters — Wed, 16 Dec 2009 08:56:50 +0000

I can only assume the Virgin Blue technical support line answers with a recorded message “having technical issues? Sometimes a power cycle can help. Have you tried turning it off and on again”?

Comment on Fire drill by Wilson Waters

Wilson Waters — Tue, 13 Oct 2009 06:32:00 +0000

You should have taken advantage of the situation – how often do you get a chance to legitimately pull off a bit of public nudity!

I happened to be down at the Curtin security building yesterday during a “real” fire alarm.

The firies promptly arrived to discover someone sucking down a quick durry in the toilet, so no big problem (well, except the expense of having the fire brigade turn up).

What amused me most was the number of calls to security asking “is this just a drill?”, “do we really have to get out?”, “There’s a strange sound coming from a red thing on the ceiling” etc…

Comment on Did you miss me? by Nettie

Nettie — Wed, 29 Jul 2009 03:24:43 +0000

Hooray! Dave is back

Comment on Same-sex marriage bill by Nettie

Nettie — Mon, 06 Jul 2009 10:30:19 +0000

But Dave… haven’t you heard? A storm is coming!

Comment on What am I doing? by Mum

Mum — Thu, 02 Jul 2009 08:40:02 +0000

I notice you diplomatically don’t mention it’s your Mum who regularly asks you that ticklish question”how’s the work going?” I do so, of course, in the bizarrely optimistic hope that something resembling an answer intelligible to earthlings of moderate IQ ensues. I am always outwitted, however. I think you win, Dave, as always!

Comment on Marvelous spam by Chris

Chris — Sat, 06 Jun 2009 12:32:25 +0000

Since you’re using WordPress, you should check out the Askimet plugin (http://akismet.com/). On my blog it’s caught 3058 spam comments automatically (with 1 false positive, but I think that was me fucking around). Couple that with Comment Timeout (http://jamesmckay.net/code/comment-timeout/) which disables comments on posts as they reach a certain age, and you’ll cut out almost all your spam.

Since doing that I’ve not had a single piece of comment spam but still get real comments.

Comment on Horrible Java by dave

dave — Fri, 15 May 2009 10:57:26 +0000

Doubles can represent integers. In fact, half of all the possible values of a double are integer values. The problem is that, beyond a certain magnitude, a double will not have enough precision to distinguish even from odd.

The real problem is that no data type, including the “arbitrary precision” ones, can possibly represent all integers up to infinity. Consider Graham’s Number for a start.

The starting point for understanding how this code works is in recognising that it is patently impossible.

Comment on Horrible Java by Neil

Neil — Fri, 15 May 2009 01:16:13 +0000

While I have no idea what Java is doing to deal with a concept of infinity, I have a problem with the code before it gets as far as using whatever infinity it has… The parity of a number is only defined for integers, so declaring i to be a double is not technically correct, and we all know technically correct is the best type of correct .

Comment on Unstimulated by Nettie

Nettie — Thu, 16 Apr 2009 05:42:32 +0000

The latest I have heard is that the government is still finalising the details of the Training and Learning Bonus – and that postgraduate students should be contacted before the end of semester 1 and invited to claim the bonus. However, this information also came with the disclaimer that noone is entirely sure who is going to be eligible to claim the bonus.

And feel free to complain if you miss out on the bonus. I’m due to finish my PhD in September, and so am likely to be looking for a job or a research position sometime in the near future – both options having been made more difficult as a result of the economic downturn. If I get this $950, at least I got something out of the world’s financial woes.

Comment on The doomsday argument by dave

dave — Wed, 08 Apr 2009 11:42:06 +0000

I see what you’re saying, and it would probably be a valid counter to some formulations of the argument.

The initial assumption is the Copernican principle, and I wouldn’t call it vacuous. It’s the Copernican principle that suggests the probability distribution – indeed, suggests the existence of a probability distribution. The statement that “any randomly selected value is 95% likely to be in the final 95% of the range” is trivial, but only once you know the distribution.

Also, let me make a subtle clarification: there is a 95% chance that you were born in the final 95% of all people. Your birth is a definable event, as opposed to “now”, which as you say is slippery and probably not amenable to statistical analysis. As in your analogies, there is no particular probability attached to simply existing among the final 95% of all people. It’s not obvious what that would actually mean.

However, given that your birth was a random selection from said probability distribution, we can estimate the distribution’s parameter. It’s a ghastly, piss poor estimate, granted. It could easily be an order of magnitude off, but it is an estimate nonetheless. We have one degree of freedom – the bare minimum for estimating one parameter. Thus, I wouldn’t characterise the doomsday argument as a prediction, but more as a kind of fuzzy constraint. You’re right that no self-respecting scientist would accept such pitiful data for any practical purpose, but the context here is rather special. This is all the data we’re going to get, and the problem is interesting enough that we may as well use it.