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Old 2021-07-21, 11:37   #18
charybdis's Avatar
Apr 2020

541 Posts

The advantage for adjust_strategy=2 with integer I seems to get greater for larger jobs. I don't know why this happens, but it does. So if you're doing a big job then you definitely will want strategy 2: saving 5% of sieving time on a c180 GNFS is absolutely worth it.

I don't know how your timings for GNFS and other SNFS jobs compare, so I can't tell what counts as slow. If you're meaning that these SNFS jobs take longer than the "rules of thumb" for SNFS-GNFS conversion indicate, then yes - that's because of the large c5 coefficient.

There is no difference between the SNFS and GNFS algorithms once we've got a polynomial. SNFS just means the special form of the number allows a polynomial to be easily found, usually with small coefficients. (Historical note: in the early days, there was more of a difference, because SNFS was initially only developed for numbers of the form b^n +- c where the algebraic number theory is easier.)
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