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Old 2005-03-02, 23:29   #1

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Default FFT size question

I've been wondering recently about the ranges covered by the various FFT sizes. On the benchmarks page the same FFT size increases between columns are colour coded i.e. green for 64K increase between ranges, yellow for 128K and lilac for 256K - is there any easy way to increase the number of ranges i.e. decrease the stepping size between ranges as exponents get bigger to effect an overall speed increase for the Gimps project? (I'm guessing there isn't a way to implement this, but just thought I'd ask) Perhaps there is a problem with accuracy - maybe a certain margin of safety is necessary at higher exponents? (then again - is accuracy/error rate a function of FFT size only? or is time taken also involved, as a slightly smaller FFT relatively would be faster).

I don't know much about FFT's themselves, so can't really say much, but it would seem that much smaller stepping (if technically possible), would give a real boost to project speed particularly at the higher exponents and also bearing in mind that Prime95 on a P4 is probably maxed out now in terms of pure processing power. (I'm doing a 34 million exponent, I've been at it over 2 months when the PCs on anyway, and I'm only 4 million in!)
Anyway, here's to M43, wherever it may lie
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