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Old 2019-01-31, 17:46   #3
VBCurtis's Avatar
Feb 2005
Riverside, CA

467510 Posts

Pretest ratio of 0.25 is really low; for a C156 you ought to do at *minimum* a T45 worth of ECM. I'd do half a T50 before GNFS, personally. (Or maybe I misunderstand what pretest ratio is)

That's about a 6-desktop-core-week job to run through GNFS; spending 1.5 days on poly select is likely about right. If you get a score within 10% of the record poly score for that size, it's "good enough". If you don't have a GPU to use with msieve, the CADO tools produce very nice polys from CPU searches.

Trying to use a poly from a different input will crash GNFS immediately with error "poly does not divide N!" or similar.
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