500 Billion Very Specialized FLOPs

sheckard writes: "ABC News is reporting about the world's fastest 'supercomputer,' but the catch is that it doesn't do much by itself. The GRAPE 6 supercomputer computes gravitational force, but needs to be hooked up to a normal PC. The PC does the accounting work, while the GRAPE 6 does the crunching." The giant pendulum of full-steam-ahead specialization vs. all-purpose flexibility knocks down another one of those tiny red pins ...

Comments

Gravity simulation algorithms

[WolfWithoutAClause]

Actually gravity simulation is pretty cool algorithmically as well as hardware wise. Originally the gravity simulators had to work out the attraction between every pair of particles. This meant that if you simulate 1000 particles they had to do 1000,000 calculations. Slow.

So along come some doods who said why don't we recursively stick the particles into boxes and then calculate the attraction between the boxes instead and it should be a lot faster. So they tried it and it seemed to work great- it only takes more like 10,000 calculations to do 1000 particles.

Anyway along came some other guys and they were a bit suspicious. They showed that some galaxies fell apart under some conditions with the recursive boxes method, when like they shouldn't. Back to the drawing board.

There are some fixes for this now- they run more slowly, but still a lot faster than the boring way. Still, its better than the end of the universe. Even if it is only a toy universe.

For descriptions of loadsa algorithms, including 'symplectics' which are able to predict the future of the solar system to 1 part in 10^13 ten million years in the future check out this link:

Haiku

[575]

Installing Grape 6
Processor of gravity
Quake sure feels real now