perfection v. progression

Well, that didn't take long. 17 sets of games, each with 15-21 levels, completed.  Not perfectly: I have a few one star, and several two star, levels, and I found only 4 golden eggs along the way, so not all the bonus levels. (There are cheat pages on the web for finding all the eggs ... but that's cheating.)

I have found only four of these

  

So what next? (I have downloaded the Angry Birds "Seasons" set of level, but am waiting for the holiday to play that.)  The game itself suggests I could try for three stars on every level. Now, I admit I did a few levels more than once as I went through, when it seemed I just lucked out, or when I wanted to explore an alternative solution.  But, I prefer to move on once I have achieved what's needed, which here is to "clear the level" of pigs.

It's important not to spend too much time perfecting what you have done, in place of doing new things.  Do something as well as it needs to be done, then move on.  If you have moved on, don't go back and redo, knowing you could do it better now. (Of course you can do it better now: you've moved on!  Only go back if the earlier imperfect version is proving a shaky foundation.)  Polishing is much easier than progression, but is often only a displacement activity.

So, I will maybe try to get better scores on a few more levels (maybe try for no one star levels, anyway) in my "spare time", but it isn't anything like the same as marching on to new levels.

Next?

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it was 30 years ago today

that Acorn Computers launched the BBC micro.

I got a model B Beeb while I was doing my PhD, and had great fun learning to program.  (I already knew Fortran IV, but until reading Structured Programming with BBC Basic, I hacked, rather than programmed.)  I used my Beeb to do some real science (see the acknowledment section on p544), and even wrote some articles on fractals for Acorn User.  Happy days, and so long ago.

30 years ago, in fact.  That's the reason for the post.  We all know about Moore's law, commonly quoted as "computer power doubles every 18 months" (although of course the reality is more complicated, but let's go with this for now).  One doubling of power doesn't sound much, but what happens after 30 years of Moore's law?

30 years is 20 doubling times. 2^20 ~ 10^6. (Impress you friends with fast mental conversions between powers of two and powers of ten by remembering 2^10 = 1024 ~ 10^3. Caveat: any friend who would be impressed by this feat probably already knows how to do it.)  So that would mean today's PCs are one million times more powerful than the humble Beeb.  Is this true?

• Memory: 32kB RAM (yes, 32 kilobytes).  32 GB isn't common today (although it is on a reasonably high end scientific workstation): more like 4 or 8 Gigs typically, so, a quarter of a million times as much memory.
• Processor (6502A) speed: 2 MHz.  More like a thousand times faster today, with a 3GHz processor (but, of course, that's with a 32 or 64 bit processor, not the Beeb's 8 bit one, and then there's multi-core, dual processors, and what not, giving another order of magnitude).
• Screen: max resolution 640x256 (2 colours), or 160x256 (8 colours), using 20 kB of video RAM.  Today, my flat screen is 1920x1080 (4 billion, or 32 bit, colours), so that's about 8MB of video memory, or 400 times as much. 
• Disc storage: a cassette player, or an optional 100 kB 5.25 inch floppy drive once you got fed up with waiting for programs "Loading...". Today, a 500 GB hard drive is more typical: that's 5 million times as much.

Okay, not every feature is a million times more, but combined, today's PCs are easily a million times more powerful than the Beeb.  And for less money!  The BBC Model B cost £399 (which is about £1200 in today's money), but that didn't include the monitor or floppy drive. The Torch dual 800 kB floppy drive cost around £800, although you got a Z80 co-processor thrown in for that.  In March 1987 I bought a 28MB (yes, megabyte) hard drive for £745 (or about £1600 in today's money).

To get a better feel for what this doubling means, think of a slightly older computer, Deep Thought, which took seven and a half million years to calculate the Answer to the Ultimate Question of Life, The Universe, and Everything.  That was in 1978, or 33 years ago, or 22 doubling times, or 4 million times.  If that was a speed improvement, today's equivalent of Deep Though would take only 2 years to calculate the answer!  Not so impressive now.

But wait, you say.  Douglas Adams was a genius.  He would have taken that into account.  The real Deep Thought would have kept upgrading itself, but even so still took 7.5 Myr to calculate the answer.  7.5 Myr is 5 million doubling times, or 10^1,500,00 more powerful.  That would make the Deep Thought who gave the answer 42 to the philosophers' descendents umimaginably more powerful than the original (if such a machine is even possible in the current universe).

Anyway, happy birthday, Beeb!

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improved!

So here's the latest box of tin foil we bought (yes, I know it's aluminium, not tin, but tin cans are made of steel, tin foil is made of aluminium, and silver paper isn't silver):

 

What caught my eye was this:

Improved thickness!  That must be good, eh?  It's improved!

But just what precisely is improved?  Well, the thickness, obviously.  But in what way?  Careful scrutiny of the box revealed no further clues. (Yes, yes, I know.  Anything to delay actually having to do any actual cooking, you see.)

Improvement presumably implies change. What changes could one make to foil thickness? I could think of four:

1. thinner
2. thicker
3. more even thickness
4. less even thickness (added simply for completeness)

But are any of these improvements? Thinner might mean less waste, but more fragile; thicker would then be more waste, less fragile.  More even thickness might be better if that made cooking times more predictable (I haven't a clue whether it does or not, I'm just hand-waving); then maybe less even thickness would make life more interesting by adding greater variability to the cooked result. 

On eventually opening the box and feeling the foil, it's definitely thicker than the previous batch.  So, that's an improvement because ... more waste?  And lo!  This box has 30m of foil, whereas the previous box of thinner, unimproved, product contained 40m of foil.

So the improvement is that I have to buy foil more often?  Well, sarcasm aside, presumably the implied improvement is that it's less fragile, that it is stronger.  But then, why not say so? Why not:

 

Or even:

Or if that doesn't have enough oomph, what about:

But ... improved thickness?

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most addictive use of a physics engine ever

I've been holding out, but yesterday I finally installed Angry Birds on my Android phone.  Four hours and two levels (of 21 stages each, for the remaining person on the planet who hasn't yet installed it) later, I decided it was a keeper.

An early, but difficult, level

And again, for that one remaining person, the concept is simple, but addictive.  You "fire" birds from a catapult (these birds don't fly, they fall with style) to knock over and blow up structures, in order to explode the pigs.  (What do you mean, "why"?)

The physics engine means that if you hit things just right, they fall in glorious cascades, squashing everything in sight.  If you don't, they fall in the wrong place, or wobble, or tilt, and you have to try again. And again.  And again.  Hence the four hours.

Different kinds of birds have different capabilities, and you get only a limited number, so you have to plan carefully.  And then you have to execute the plan, which involves a combination of skill and luck (that's the way the castle crumbles).

It took me back a couple of decades, to Lemmings, which absorbed a lot of life back then (I really should know better by now).

more screenshots available

What impressed me those years ago about Lemmings was the implicit training programme.  At the computer show (remember them?) where I tried it, and bought it, there were three demo levels: v triv, triv, and impossible.  After having played it for several months a completely non-significant part of my life, I realised I had just sailed through the "impossible" demo level, having been thoroughly and efficiently trained in exploiting Lemming capabilities to solve fiendish mining problems. Angry Birds (and, I assume, all its ilk) has the same approach, introducing the new capabilities one by one, having specially designed levels that you use these capabilities to solve, and slowly increasing difficulty, to keep you engaged.  In addition to being a brilliant teacher, it's a brilliant implementation of what Csikszentmihalyi calls "flow".

Time has moved on since the relatively simple graphics and trivial dynamics of Lemmings.  Angry Birds has that physics engine which gives a whole new level of realism (although I do think the friction model is a bit too sticky). But Lemmings had its own great feature: insanely compelling use of background music. To this day, whenever I hear a certain piece of Mozart, I flash back to images of hordes of grimly marching lemmings.

Now, have I got time for just one more go before lunch? 

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On the Road to Mendeley

I decided to evaluate Mendeley as a means to "organise" my scientific paper reading and note-taking. A hard disk full of PDFs from forgotten sources, with separate BibTeX files for each paper I write, is messy.

I decided on Mendeley after reading a few reviews. These mostly said good things, and only very few bad things. The desktop application lets you keep the PDFs of your collected papers (and other materials) together, along with notes, tags, and bibliographic information.

You can search on authors, keywords, tags, text, and so on.

You can keep papers in separate directories.  Having recently started using Gmail, and got the hang of using tags instead of directories to classify my emails, I was pleased to see tags also supported here. I will be tagging papers not only with the bits of their content of interest to me, but also to tell me which of my own papers have referenced them.

You can export reference information in BibTeX format, for ease of writing papers. (Apparently you can also export in MS-Word formats; but why would you write a scientific paper in anything other than LaTeX?)

So I spent a happy few hours importing my PDFs, and various BibTeX files, merging duplicates, cleaning up the entries, and generally populating my account:

You don't have to have a PDF of every paper: you can store just the bibliographic details, or a URL to where it is stored elsewhere.  But if you want to annotate the PDF, you need your own local copy.  (There is a separate "notes" field, so you don't need to do this unless you want to annotate in the exact place.)  You can sync all this information across multiple computers. (I haven't tried this yet: I've only accessed it from home so far). I can see that free 500MB isn't going to go very far...

I'll try using it for a while, and in anger while writing my next paper, to organise the bibliographic information.  So far it looks very useful.  It's the kind of thing that will make writing a review paper a lot easier, I suspect.

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Hero to Zero

I love Coke.  It's my soft drink of choice.  But there's a problem.  A 142 Calorie per can problem.  So I restrict myself to about three cans a week.  I did once try a Diet Coke (by accident!); ghastly tinny taste.

Scalzi has recently blogged about Coke Zero, his soft drink of choice. Part of the reason for his choice is its (lack of) calorific value.  I was interested when he mentioned that, whereas Diet Coke uses the "New Coke" (bleurggh!) recipe,  Coke Zero uses the (One True) Coke recipe.  (Calling Coke "classic Coke" merely legitimises the existence of "New Coke", which I refuse to do. And UK cans don't even need to say "classic" on them.)

I wondered, maybe the tinniness of that long-ago Diet Coke was due to the recipe difference, not to the sugar substitute?  Maybe Coke Zero tastes like Coke, and I could save myself 142 Calories a shot? (Slightly less, actually. Coke Zero has about 2 Calories a can.)

So I tried it.

Nope.  Still tinny.

:-(

Mind you, I know I can taste bitterness where many can't.  For example, I think lettuce is horrible.  Nasty bitter tinny after-taste.  When I Rule the World, the first thing I will do is outlaw lettuce.  Or at least outlaw it being put in every single kind of sandwich.

Many friends express disbelief in my dislike of lettuce: "but it doesn't taste of anything". (So why are you so keen on eating tasteless food, then, eh?)  Oh yes it does.

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scientific abstract

Scientific and technical writing is a little different from the kind of "creative writing" you are taught at school. There are different conventions. For example, "vary your vocabulary" is a complete no-no if you are striving for precision and lack of ambiguity. If you think using the same word several times may sound a bit clunky, and you decide to make things "read better" by using synonyms instead,  imagine the internal dialogue of your readers going something like this: "You talk about a thingumabob here, a thingamajig there, and a whatchamacallit in your other paper. What subtle distinction are you trying to make? I've been trying to puzzle this out for ages.  Oh, I see.  You are just varying your vocabulary. Come here and say hello to this two-by-four." That should help you decide not to do it.

One important part of a scientific paper is the abstract. It should be short yet comprehensive. It should tell you what the paper is about, the question the paper addresses, and the answer it discovers. It is not a spoiler to put the answer in. You are not writing a blurb for a whodunnit. Don't worry that you are giving away the punchline. The abstract may be the only part of your paper the reader even sees.

So I was delighted to see a paper with an excellent abstract quoted at Ben Goldacre's secondary blog. (Actually, it's only the perfect abstract when combined with the paper's title; techincally, abstracts should be stand-alone. But, hey.)

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