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Old 2020-08-04, 05:03   #111
VBCurtis
 
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"Curtis"
Feb 2005
Riverside, CA

119316 Posts
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I view mfb and lambda both as methods to control the amount of wasted cofactor-splitting. For reasons unclear to me, CADO runs quite a bit faster (in extensive testing at 100-140 digits) with mfb set well below 2*lpb. I've been using lambda as a sort of floating-point control for mfb, and on small numbers I have lots of runs where changing lambda by 0.01 does change the yield per Q but also the number of relations needed (in the direction that suggests the job is effectively a smaller LP choice). I found that using LP choices 1 or 2 bits higher than traditional choices but tight mfb led to faster factorizations.

I suppose I won't be too surprised if that doesn't work at this size; 31/32 is pretty much traditional for this size of job, so perhaps a tight mfb or tight lambda setting is overly restrictive.
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