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Message boards : Primegen : What is the purpose of primegen?

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stanekProject donor
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Message 6942 - Posted: 13 Sep 2007 | 2:40:37 UTC

The other 3 applications, woodall, cullen and twin prime search are pretty self eplanitory but what the purpose primegen?

Is it creating the list of primes starting at 0?

If so, does creating this benefit in any way to the other 3 projects currently running?

If possible could anyone explain to me the method of how this application works, in theory or in detail.

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Message 6947 - Posted: 13 Sep 2007 | 19:20:35 UTC - in response to Message 6942.

The other 3 applications, woodall, cullen and twin prime search are pretty self eplanitory but what the purpose primegen?

Is it creating the list of primes starting at 0?

If so, does creating this benefit in any way to the other 3 projects currently running?

If possible could anyone explain to me the method of how this application works, in theory or in detail.


PrimeGen did actually start from 0, and at last check-up I did a while ago with Rytis, it was crunching and finding Primes around 570,000,000,000!

The findings aren't beneficial to any other projects running here, but someday they might be valueable other applications and other projects, who knows that holds for the future to tell :)

Third question, well the theory you have to ask Rytis, but it searches all odd numbers in a range of 100,000 and find all (at the moment approximately 3,200) candidates in the given range. Your WU will typically show at what upper bound your WU stops, (upper number checked) if you add 5 zeros to the number in the PrimeGen WU name :)

Hope it helped, else feel free to ask again. By the way I may add, if you're hoping to find WorldRecord Primes, don't use PrimeGen, it will never find them, that however will any of the other 3 (sub)Projects currently running, though there can be far between the Primes :)

Regards!

KEP!

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Message 56201 - Posted: 8 Jul 2012 | 13:59:03 UTC

The lists could be used for stuff like quad. sieve(s)...
you can never have enough numbers to do that... ;)

instead of using (2 and) all odd numbers you could use that list... less division to do...
instead of saving e.g. 15 = 3*5 = {3,5} you could save 15 = {index(3), index(5)} = {1,2} <-- no space between "neighbours"...

with a list based on 32 bit entries:
instead of ~8.000.000.000 (only the odd) numbers
you could save more than 100.000.000.000 IDs...


with a new pc the lists can be created @ home quite fast...
got ~48.000.000.000 primes by using 1 or 2 i7 PCs for ~3 weekends (~200 hours)...
(Linux, C++, 64 bit, programs almost @ optimum, CUDA was not used (yet))
~45 GB --> with extra index-files it should fit on 1 DL-BR (50 GB)
zipped version would be ~30 GB... could be saved on a large SD - as backup...

would be overkill for QS@home (~36 bit to save 1 entry)
--> I guess primegen results would be quite useless today...

Message boards : Primegen : What is the purpose of primegen?

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