Thread: 6- table
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Old 2009-05-03, 16:02   #8
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fivemack's Avatar
Feb 2006
Cambridge, England

2·7·461 Posts
Default 6,347-

Sieving by Bruce Dodson, parameter selection and completion by Tom Womack. This may be the first job with 32-bit large primes both sides to be finished with msieve.

Polynomials x^6-6, x-6^58.

Small primes up to 160 million on both sides, sieved with 15e for Q=10M-170M algebraic side and Q=10M-260M rational side. 367372454 unique relations from something over half a billion raw (better estimate of runtime and rawrelcount coming soon).

36 hours on one CPU of a 12GB i7 running at 2.8GHz, with peak memory usage around 10GB, to get to

Sun Mar 29 21:56:52 2009 weight of 19120844 cycles is about 1338865042 (70.02/cycle)

and another two hours to get to

Mon Mar 30 00:06:39 2009 matrix is 19036824 x 19037072 (5329.0 MB) with weight 1283623590 (67.43/col)
Mon Mar 30 00:06:39 2009 sparse part has weight 1206600171 (63.38/col)

The slight oddity in the filtering was 19311242 "warning: zero character" messages appearing on stderr.

Then four threads of the i7 crunched fairly solidly (with one small pause caused by the system disc on the i7 machine failing) for 821 hours, using ~6.5GB RAM, to get 14 dependencies.

Square root done on two threads separately (I tried four, but it needs 4.5GB RAM peak per thread), three hours per sqrt, initially two dependencies per thread, and each thread found one of the P96 factors.

Oh yes, the factors: 6^347-1 = 5 * 16657 * 92013588619490399 * P58 * P96a * P96b


P58 = 8023776342054310550242315692074754087050026551393750990167

P96a = 112962017521735300449115732149174215721837276361901343007283764634643624748720079471271422964001

P96b = 150229032135327752933222419558205115221308398344159056674278560696885280711039602252138197654667
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