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Old 2009-09-21, 21:51   #1
jasonp
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Oct 2004

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Default 48-bit large primes!

SVN 55 and up now include support throughout the NFS postprocessing for prime factors up to 48 bits in size for relations. The changes were fairly straightforward, but it took a great deal of time to rearrange the code to be modular enough for the changes to just drop in.

Runtime should not be affected adversely (most of the filtering uses an intermediate representation of relations that doesn't care how many bits the primes have) although memory use at the start of singleton removal will increase somewhat.

I've done some basic tests for large primes < 2^32, so who wants to be brave and use wildly inappropriate large prime sizes on a small job to test large primes > 2^32 ? Can the GGNFS siever even handle large primes that large?

These changes should hopefully be enough so that the only bottleneck to doing huge jobs is the linear algebra. I don't know when I'll be able to focus my attention on that, but hopefully these changes buy me some time to stay ahead of mersenneforum and NFS@Home :)
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