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Old 2011-12-27, 21:44   #5
(loop (#_fork))
fivemack's Avatar
Feb 2006
Cambridge, England

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Default Reply from Thorsten

(I have of course asked his permission to forward this)

Is there a newer version of lasieve around than the lasieve5 dated November 2008 which you supplied to Alex Kruppa and is attached at ?
It is identical to the latest version I can find.

mersenneforum is gearing up to try to do some >200-digit GNFS job, and the version of lasieve4 that we've been using in the past is not coping well with the very high-skew polynomials that Jason's latest polynomial optimisation tends to produce.
If the lattice basis for a special q does not fit into 31 bits this special q is discarded. If the number of discarded special q gets too high for your project you might modify the function reduce2 in redu2.w to keep more special q (although the sieving for them will be less efficient). This does not really solve the problem, but adapting the code to high skewness is more difficult and you probably do not want to wait until I finish the new version (>=1 year I expect).
In the case that you want to use the I=15 version, you could try to use the I=16 version with parameter -J 13 (so sieving area 2^16*2^13 instead
of 2^15*2^14) which will probably discard less special q.
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