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At work, I've the good fortune of having a two-CPU workstation on my desk.

Unfortunately, whilst the two CPUs are within a centimetre of one another on the same piece of silicon, they appear to maintain independent clocks running with a noticeable offset; I can't tell if the speeds are also different.

In any case,

a = clock()
multi_threaded_operation()
b = clock()

can leave b reading out as several seconds before a, if the main thread was initially on the core with the later clock and got rescheduled onto the other one after the operation. This is not helpful for seeing which things are actually faster than which others.

Is there a standard C library routine, or at least something in <sys/*.h>, guaranteed to read a clock of a kind such that I can be reasonably confident that the computer's got only one?

Is there any shell which maintains an at-all-sensible command history when you're working with several terminals each with half a dozen sessions in tabs? Intercalating the history from multiple sessions would probably be ideal for my current working style; appending the history from each session as a lump when the session closes would also be fine; but at the moment tcsh seems to maintain history for at most one session, randomly-selected, and this makes 'history' less than useful if I actually want to work out what I've been doing.

Gorgeous weather, so Saturday I cycled to Ickworth; basically a straight line due East from Cambridge: Fulbourn, Great Wilbraham, Little Wilbraham, Six Mile Bottom, Dullingham, Wood Ditton, Saxon Street, Ousden, Hargrave, Chevington and across the estate to Ickworth. 37.1km [OS 444595 -> 815615] as the crow flies; nearer 55 as the cycle wheels roll; took me three and a half hours.

Wood Ditton water tower

Intended view of the main hall at Ickworth

I recommend this as a trip; glorious Suffolk villages, with a number of big stables as you pass to the south of Newmarket, and roads undulating enough to remind me more of the Cotswolds than of Cambridgeshire. The house at Ickworth is nothing special on the inside, though the gardens are impressive, buzzing with bees in this weather. After Ickworth, up into Bury St Edmund's and a 45-minute train ride, in a one-carriage train with two bicycle racks, back to Cambridge.

Sunday dawned cold and misty; cycled to Histon and spent an hour and a half with Grandma, then to the end of Mill Road for

major_clanger's birthday and off-to-Basra party. Great food, nice people, conversation about all things from rocketry to the political implications of the shalwar kameez, copious cider of the finest quality;

purpletigron and

bugshaw may be glad to know that the black coffee afterwards was also adequately copious, and I made it back home without incident.

I think I will go to sleep now.

My Personality


Neuroticism	52
Extraversion	21
Openness To Experience	32
Agreeableness	80
Conscientiousness	31

Test Yourself Compare Yourself View Full Report

MySpace Surveys, Bebo and MySpace Layouts by Pulseware Survey Software

Actually quite surprised how plausible the personality descriptions sound, though 'Others describe you as down-to-earth, practical, and conservative' is I think inconsistent with anyone I've heard describing me, and 'You prefer dealing with either people or things rather than ideas. You regard intellectual exercises as a waste of your time' makes sense only if 'intellectual exercises' are crosswords and Sudoku rather than elliptic curves and image-processing problems.

I didn't have much fun doing academic research, but building the tools that researchers can use does appeal to me. Yesterday, I solved the structure of a protein.

That is, I took some diffraction images collected as a calibration exercise on Tuesday at the ESRF synchrotron at Grenoble, downloaded the PDB entry for trypsin, and got one of our company's products to convert the images to merged intensities and another to convert the merged intensities to a protein structure. It required the invocation of three programs with four command-line options apiece, an hour and a half of processing on a computer which cost £800 last year, and a total of nearly two minutes of thought, spent figuring out which the positive X direction on the detector was.

Today, I did Porcine Olfactory Protein; this is a small protein found in abundance in pig snot, which binds promiscuously to a vast number of odiferous molecules. I took data for one of its bound forms (PDB 1E00), removed the ligand, collected someone else's intensity measurements for a different bound form (PDB 1DZJ), invoked REFINE, waited an hour, and got a pretty purple and green 3D diagram in which you could see what the new ligand (a peculiar pungent selenium- and nitrogen-containing heterocycle) was doing.

Max Perutz and John Kendrew took thirteen years of false starts plus nine years of concerted effort to compute a protein structure in 1960, the first time it was done, and won a Nobel Prize thereby. It now makes for a slightly upmarket GCSE biology exercise, for which the tedious part for the teacher would be getting licenses to the necessary software. I do like the twenty-first century.

Does anyone want to buy my last-but-three digital camera?

It's quite nice and chunky and child-proof, and the sort of thing I'd have been ecstatic to have when I was seven.

And I've had fun writing the description on ebay:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=110028254249

2361633138713^4 + 2378932615558^4 + 4978964945231^4 = 18*2477071347133^4

Which is to say, since I've not suddenly got my hands on ten trillion times as much compute power as I had on Sunday, I've actually managed to find an embedded elliptic curve in one of my quartic surfaces. http://tom.womack.net/quartsurf has the details, more information about quartic surfaces, long lists of points, and other things to amuse the easily numerically amused.

is the traditional reason to visit Krakow, though this is probably the best view you get of it; the interior is very dark and very tourist-ridden.

represents one of the other reasons to visit Krakow, namely that it's about the best place in Europe to learn about current cultural and drinking trends amongst middle-class university-age Australians.

I am not altogether sure what the userpic for this entry, observed on a sign in a Polish park, is intended to prohibit, but it's beautifully iconic of its kind. Looking at the arrangement of the text on the sign, it may mean "Niszczenia i uszkadzania urzadzen, budynkow i budowli parkowych"; my West Slavic is insufficient to decipher. I can make a pretty good guess at the parts of speech of each word in "Umieszczania bez zgody administratora tablic, napisow oraz ogloszen", I just have a little trouble with the vocabulary.

There's something about renting in Cambridge that makes one sigh at seeing things like http://www.viviun.com/AD-48729/ in Polish estate-agent windows; on the other hand, I really don't have the background required to make owning a gite in Silesia a viable life choice.

Should you ever have been curious about the integer points on the quartic surface x^4+y^4+z^4=N*t^4, the program here will find them with reasonable speed. Call it with 'four N limit'; if you have lots of processors to use, 'four (N) (limit) 0 (limit/4)' on the first one, 'four (N) (limit) (limit/4) (limit/2)' on the second and so on.

1949^4 + 4727^4 + 12389^4 = 2657^4 * 483

It takes a minute on a 2.4GHz Pentium 4 with a very old motherboard for 'four 163 10000' to find all the points on x^4+y^4+z^4=163t^4 with less than five digits in each term, or about ~~twelve~~fifty¹ hours for 'four 1 500000' to find the first-discovered-in-1986 smallest point on x^4+y^4+z^4=t^4; the program uses about (limit/30000) megabytes of memory, and time a little over quadratic in (limit). I'd be interested to see how fast it runs on actually-fast modern computers, if any of my readers have one, and a C++ compiler, and the desire to run 'time four 163 10000' and wait a minute for the result.

Some of the points on these surfaces are known to be connected with points on elliptic curves lying on the surface (which is why a separate program of mine managed to find 7592431981391^4 + 22495595284040^4 + 27239791692640^4 = 29999857938609^4, which would be found by the simple search program only after some thousands of times the present age of the universe); the only problem is that I have no idea how to get from a known point to an elliptic curve that it happens to lie on. I obtained the big point by using a known elliptic curve and finding large points on that using standard software (part of which I developed for my PhD), but I haven't yet managed to find any elliptic curves for N not equal to 1.

On the other hand, it may well be that there are points on the surfaces which lie on no elliptic curve; nobody has a clue how to find those by any methods cleverer than the one implemented in the code above.

¹: it turned out that the run-time is a bit more over quadratic than I thought it was

Britain may be a nation of peculiarly obsessive meteorologists with a dearth of institution-destroying political action in the last fifty years, but a consequence of this is that we've got peculiarly wonderful climate data recorded, from which maps like this and this can be produced, leading to awkward questions like 'why isn't Ipswich, being as it is so dry and sunny, thronged by mobs of pasty English tourists'?

Does anyone know of such maps, at a reasonable resolution (being able to see individual Welsh mountains is clearly excessive, but this isn't really accurate enough) for continental Europe? It was clear that there was a lot of climactic variation between Gdansk and Krakow, I'd be interested to know what it is that balances out the sunniness of La Rochelle to leave it as unpopulated as it is.

It was perhaps not entirely traditional to end my trip to Poland with a visit to an exhibition of art-deco Japanese posters followed by sushi on the banks of the Wisƚa, or to bring home as souvenir a rather nice set of tea-bowls and an attractive blue cracked-glaze Japanese teapot; but I suppose slavish adherence to tradition isn't among my strong points.

A slightly tedious trip back (got to the airport three hours early, no cabin luggage, the plane left an hour and a half late, and two hours later you're in Luton), but no worse than to be expected in the circumstances; my camera-case survived the risks of theft and damage.

I've an Easyjet flight booked Saturday afternoon from Krakow to Luton.

Easyjet flights out of England are quite comprehensively cancelled, which I imagine means by the Law of Conservation of Aircraft that everything except the absolutely-next flight from any destination into England is going to be problematic; I'm having visions of the entire Easyjet fleet lined up wing-tip to wing-tip at Luton, rather as I saw the entire Air Paradise fleet lined up in a line at Kuta after they went suddenly bust.

Which I think means either I wait in Poland until the problems are resolved -- and I'm reluctant to bet on how long it will take for the professional paranoids of Thames House to loosen up on their paranoia -- or attempt to head home over land.

A train from here takes 25 hours via Poznan, Cologne, Brussels and the Chunnel, which, whilst I've only a book and a half left, sounds a lot more fun than long waits at Krakow airport; on the other hand Eurostar tickets for immediate travel appear to cost 150 pounds, and the long overland stretch is probably about the same. A bus takes no longer and is 90 pounds, and maybe no more uncomfortable.

Or am I being silly, panicing in advance of the facts; should I simply wait and check on Saturday afternoon if my flight actually exists, and rely on my boss not to mind too much if geopolitics keep me from work until Tuesday.

There is a particular sort of malaise that afflicts the surroundings of major railway stations, Warsaw perhaps more so than many; under the station is a warren of passages crammed with alternating newsagents, all-night kebab stands and malodorous cheap Internet cafes, outside the station is a gigantic Stalinist square surrounded by six-lane highways with the Palace of Science and Culture sitting gigantically and Stalinistically in the centre.

The Old Town, completely rebuilt between about 1965 and about 1980, is pretty if tourist-driven; the Museum of the History of Warsaw is really very good, though cutting off abruptly in 1990. I wonder why the stories of what Polish scouts did in the Uprising weren't at least as repeated as the tales of Mafeking when the Scouts were recruiting at school; I suppose, like everything in the Uprising, the happy ending was postponed forty-five years and an awful lot of the principal characters had died in Soviet custody or in London exile in the meantime. The Monument to the Uprising takes up about half a city-block, and was opened on August 1 1989, about the first moment it could have been.

There's also the Uprising Museum; it is surrounded by a long fence of about 130 sections, each section of which is made of five slabs, each slab has fourteen names of the fallen inscribed on it. It's a good museum, of the modern well-labelled maze variety; made me wonder (

papersky almost certainly knows this) if there's a collection of Orwell's wartime writing for the Tribune available. They had an animation of the Allied and Soviet front lines over 1944-45, which reminded me how little history I know; I had no idea of the existence of the second Allied front in France up around Marseilles a few months after D-day, and only a dim one of how unstoppably the Soviet lines thundered West after Stalingrad. Nor was I anything like so clear how much of a bastard Stalin was.

Aside from that, there's ice-cream, a large amount of municipal green space (I supposed municipal green space was a cheap thing to provide in a city 85% of whose buildings were raised, though in fact the parks were there from the beginning) equipped with incredibly tame biscuit-stealing red squirrels, shiny skyscrapers next to unpainted brut-concrete apartment blocks, and a large artifical palm tree on Charles de Gaulle Roundabout.

One of the more notable features of Norfolk is the number of large churches built, presumably for lack of any other socially acceptable form of conspicuous consumption, in the middle of what are now tiny villages.

Gdansk is much the same, except that Gdansk is rather smaller than Norfolk so the churches get in each others' way rather more. There's one on roughly every other church corner. They're made of brick - this area doesn't really have the geology for stone - and accordingly are ponderously enormous, with stubby towers since any Lego aficionado knows the difficulties of building delicately soaring spires out of brick. Some of them have delicately soaring spires made out of copper and stuck on top of great solid brick pedestals.

Other than churches, there are the houses of rich Hanseatic merchants, built out of monumental brick and then plastered in blues and greens; some of these have turned into fine tea- and chocolate-shops (until today I was unaware how nice pineapple coated with dark chocolate could be), some into museums, some just sit there being placidly Hanseatic at onlookers.

World War Two started here, and (with Nazi troops holed up on one of the peninsulas) pretty much ended here too, so the old town is, understandably, all relatively new; a 'built MDCLI' sign will have been saved from the rubble and proudly re-gilded and inserted into a building once the reconstruction finished in MCMLXXI. I don't think any church roof survived, though most of the massive brick frontages remained with the already-dark bricks burned black.

There's a good exhibition at the now-deserted Gdansk shipyard on protests against the regime in Poland; everyone knows about the 1980 Solidarity strike, I hadn't heard of the much more violently cracked-down-upon 1956 and 1970 strikes. Lots of contemporary film footage and photography, which as always makes you wonder how the regimes managed to find quite such numbers of straightforwardly violent goons for their Internal Oppression Forces. They're not the regular army; regular armies usually stopped when the strikers suggested that might have been a good idea.

The 'im. Lenin' under the sign on the great gate of the Gdansk shipyard has been removed, and a proud 'S.A.' (equivalent of 'Ltd') put in its place; though I have a feeling that the shipyard went bust some years back.

At the moment, as I think every August, it's the Festival of St Dominic, and the streets are filled with stalls selling amber jewellery (this is the amber capital of the Western Baltic; there is apparently more amber in the amber capital of the Eastern Baltic in Kaliningrad, but you need a Russian visa to go there), clothing, massage armchairs, waffles, exceedingly sharp knives, ice-cream, replica handguns, and things which look like meringues but are in fact made out of hard salty cheese, a sort of denser uber-Wensleydale. You can guess which of these I bought.

There don't seem to be many corridors here in Gdansk, nor in Szczecin was there any sign of a long-disused iron curtain-post.

On the other hand, as a city to get lost in at night knowing only six words of the language, none of them 'lost' or 'map', Gdansk during whichever festival they're holding at the moment can scarcely be beaten.

Had I not visited the museum of Vor- und Fruhgeschichte in the Charlottenburg yesterday morning, I would still be ignorant of the use of the duck as cult-object in Iron Age Europe, and would not have seen the Ceremonial Object in approximately the shape of a multi-person bicycle, with three front wheels, two sets of handlebars in the shape of bulls' horns, and four seats in the shape of ducks. I have many photos to regale you with on my return.

There is, I fear, a good reason that 'as fun as a wet Saturday in Stettin' has not entered the English idiom; the cathedral is large and has a very strange stained-glass window depicting Lech Walesa building Noah's Ark with the cranes of the Gdansk shipyard, there's a large Castle of the Dukes of Pomerania looking over the city, the interior of which has been converted to an opera-house and a museum of unlabelled small pieces of castle-building equipment, and the City Museum is shut for restoration. Also, through a combination of my lassitude and my ineptitude in reading timetables, I get three hours awake here, ending in about ten minutes as I board the train to Gdansk.

Polish pancakes are of the size and thickness of pizzas, and rather stodgier.

Also, Livejournal is very carefully localised and so is currently giving me all the buttons labelled in Polish, a language harder to follow by analogy to Russian than I'd expected. Thankfully the buttons are all in the same places as they were in English.

Current Music: Oysterband:The track goes on forever across the Polish plain

I think Berlin is still my favorite city to visit; the new buildings feel as if they've only just been taken out of their boxes and many of the old ones as if they're freshly back from the dry-cleaners, massive green areas, superb public transport, bars that never close ...

The conference was quite hard work (nine to six Sunday through Wednesday meaning that I end up with a week feeling as if it contains two Fridays); met up with various people from my past, all of whom seemed to decide that I needed luring back into academia, or at least luring into long evenings spent sipping Pilzener, eating predominantly pig-based dishes, and discussing how much fun life as a post-doc is. I don't think it'll work, if only given quite how incomprehensible I found some of the talks; there's clearly some sort of taboo about mentioning actual equations or numbers in algebraic-geometry talks.

Aside from that, and walks through the Tiergarten and down the Spree, I've visited what's presumably going to be a travelling exhibition of artefacts from Alexandria harbour - granite colossi, a six-metre-high tablet describing in hieroglyphs the achievements of a minor Ptolemy, golden earrings, and more ceramic bowls of uncertain use than you could shake a stick at. Diorite survives immersion very well, though pink granite tends to lose its polish.

Charlottenburg and Potsdam tomorrow, and then on to Poland; but I seem to be spending the afternoon today buying sunscreen and waiting for washing-machines to finish, having spent the morning recovering from the last few evenings.

There's a transaction-processing benchmark, results listed at www.tpc.org, for which major computer manufacturers are prepared to spend millions of dollars of engineering time and use tens of millions of dollars worth of hardware.

The current top entries are offering rates of a couple of million transactions per minute, which translates to between one and two trillion transactions a year since there are almost exactly half a million minutes in a year.

I've just looked at ebay's financial statements, which indicate that 2.5 billion items are sold through ebay annually; if we assume that each bid is a transaction and that each item gets twenty bids, that's a hundred thousand transactions a minute.

Tesco's sales are on the order of £40 billion a year; even if we assume that each item on a bill is a transaction, the average Tesco item cost more than 50p, so that's less than 80 billion transactions a year, 160,000 a minute. Wal-Mart has about five times the sales of Tesco, which brings you to half a trillion; a million a minute.

What exactly is the point to IBM or to HP of demonstrating a single machine capable of handling all the transactions at every supermarket in the European Union? This seems the kind of machine of which they can sell one.

Beirut, at least until yesterday, was a fairly safe destination; I know at least one of my friends-list readers and the sister of another have been there and enjoyed it greatly. The FCO has always advised against travel to the Bekaa valley, but otherwise reckoned Lebanon was a fairly safe place to visit.

The Israelis have just bombed Beirut airport, blockaded Lebanon's ports, and made moves to close the land border. The diplomatic language is getting quite heated: the French foreign minister is using terms like 'disproportionate act of war'. I wonder how many British civilians they have started to hold hostage? (though I assume that Bashar al-Assad will graciously allow the stranded Westerners to leave by way of Damascus).

I think now is a good time for me to stop reading the news and concentrate for this afternoon on reading the documentation for the company's new software release.

Jesus Green is surprisingly nice at this time of year; not energy-sappingly chilly, and it's pleasant to discover that I can in fact swim a hundred yards at a time without stopping. Twelve lengths, so a bit over a kilometre; four each breast-stroke, back-stroke and crawl. Fast crawl took me just over three minutes but left me heart-pounding and distinctly dizzy; the other strokes seemed to take about 4.5, though I think I always managed under five minutes — looking on wikipedia, this is almost exactly four times as slow as the world record holder, which is probably the best spin I can put on my unreasonable sluggishness. I was a bit surprised to find that I had trouble walking in a straight line as I got out of the pool at the end of the swim; chlorinated ears?

It's clear that I hang around at the ends of the pool for as long as I think I can get away with, so Jesus Green's having a quarter as many ends as Parkside is an advantage.

Sadly I managed to miss

numberland; I'll try again next week.

The exercise has left me too tired to spend the evening sitting creatively in front of a hot iPhoto to prepare the full shiny photo-post that I promised

taimatsu, but look what I saw at the weekend:

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Tom Womack

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Tom Womack

Recent Entries

Two processors, two clocks

post-diluvian shells

Excellent weekend

A meme! It's a meme!

Work is fun

Touchingly unacquainted with the conventions of commerce

Numbers of Unusual Size

Pictures, and Polish, from Poland

What Tom does on a rainy Sunday afternoon

Climate data

No longer in Poland

Flights (or, possibly, trains)

Warsaw

Come and visit Gdansk before it becomes popular!

(no subject)

Duck cults of Pomerania

Berlin remains fun

Why demonstrate 3 million TPC-C?

Hostage-takers

More swimming, at a quarter of world-record pace.