Running Fast- China.

Chases US.

China has finally achieved its ambition of becoming a calculating superpower with news that one of the country's supercomputers is now the second most powerful number-cruncher on earth.

The Nebulae system at the National Supercomputing Centre in Shenzhen in southern China has been ranked by the prestigious Top500 list as having a sustained calculating power of 1.271 petaflops, or in layman's terms, 1,271 trillion calculations per second.

That is still slower than the US Department of Energy's 'Jaguar' in Oak Ridge Tennessee, the world's number one supercomputer, which can manage 1.75 petaflops, but is the first time that China has appeared so high up the Top500 site's twice-yearly rankings.

To put all this calculating power into perspective, according to figures quoted by the BBC, an average PC would take 10 hours to match the Jaguar's output for one second.

As impressive as the rise of China appears on the list, the US still dominates the overall top 500 rankings, accounting for 282 of the world's fastest machines, with Europe accounting for 144, China 24, Japan 18 and India five.

The UK scored quite well on the list, with 38 top 500 supercomputers, ahead of France's 29, and Germany's 24. One of the UK's top systems is still Edinburgh Parallel Computing Centre's HECToR, opened two years ago by Alistair Darling.

The US still utterly dominates the league in terms of hardware. The Chinese Nebulae is built using Intel and Nvidia microprocessors, both US companies.

As important as these rankings are taken by supercomputer engineers, the industry has an unknown number of 'classified' government machines that are never revealed to the list builders. The list also does not measure the practical use to which the machines are put beyond simply looking impressive on paper.

Increasingly, they are being used to create knowledge by modelling complex events in science and quickly assimilating massive volumes of data from prestige science projects. They were for a time also, famously, used to play chess, as in the 1997 head-to-head between chess champion Gary Kasparov and IBM's unblinking Deep Blue.

"I just think we should look at this as a chess match between the world's greatest chess player and[pause]Garry Kasparov," said then IBM head Lou Gerstner of the contest.