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Old 2021-05-18, 14:43   #25
VBCurtis
 
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"Curtis"
Feb 2005
Riverside, CA

27·3·13 Posts
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No, there's a flag like filter_maxrels that lets you control the number of relations msieve uses.

TD 100 vs TD 110 shows you the effect of using higher target densities for a given set of relations- the difference is not very big. A higher density matrix is slightly tougher to solve than a lower-density matrix of the same size, but matrix size affects time-to-solve much more.

More relations -> smaller matrix.-> shorter LA time.

Higher TD -> makes sure you have enough relations for a reasonably small matrix.

When filtering with msieve, let's say you have 190M relations. TD = 90 might build a matrix 11M in size, while TD 110 fails and asks for more relations. If you use the full 220M relations, TD 90 might build a 7M matrix, while TD 110 builds a 6.5M matrix. The idea is that choosing TD = 110 makes sure you avoid the situation where a matrix barely builds and is quite large (e.g. 11M for this current factorization).
If you actually try these tests, let the matrix-solving step run for 1% completion, and note the ETA (ETA is pretty stable by the time 1% is done). The TD100 and TD110 ETAs won't be very different, I expect.
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