20130723, 19:21  #56  
Nov 2003
2^{6}·113 Posts 
Quote:
changes. What you want to minimize is: Sieve_area * loglog (max prime in factor base) * #special_q. Sieve area and max prime are input parameters. Their product represent the time to sieve each special_q. For a given pair of values assigned to these parameters you estimate the number of special_q that you will need by trial sieving (say) 20 different special_q over your anticipated range of special q. This will result in a YIELD CURVE. (yield changes as special_q changes) . Now, you want the area under this curve to equal the number of relations you will need. This latter parameter will depend on the size of the large primes and the size of the factor base. Choose the maximum special q so that this area is sufficiently large. For an example of deriving a yield curve (albeit in the context of a line siever, but the ideas are the same) read my paper Parametric Optimization of SNFS. 

20130723, 21:46  #57 
Apr 2010
Over the rainbow
2·1,217 Posts 
I wanted to add that, if you put a harsh bond on np1, the nps can keep up, allowing you to use t 2 or t 3 without falling behind

20130723, 23:02  #58  
"Curtis"
Feb 2005
Riverside, CA
17·257 Posts 
Quote:
Imagine that stage1norm restricts the second coeff for each first coeff; there is no reason to believe this helps produce better polys, but the code must perform the same overhead per coeff, so cycles are wasted. Last fiddled with by VBCurtis on 20130723 at 23:06 

20130724, 00:55  #59  
Jun 2012
5466_{8} Posts 
Quote:
In the shallow end of the factorization pool where I swim, the sec/rel and yield measures seem reasonably well behaved as spec_q increases, and I only use the sieving time estimate to normalize the performance of various polys for comparison. But I will explore the method you've described. 

20130730, 01:13  #60  
Jun 2012
2·5·7·41 Posts 
Quote:
Code:
n: 2203286292154236920662074580008136560385550762038571072069284129582298550469011615783387269827436918721335468107066200517568432204890391543672088684775850203864157356993 skew: 5721717.05 c0: 252681583117408750059938913868667397960 c1: 716807602129660819233465802155626 c2: 1024911528196794072738767285 c3: 155515608837130473266 c4: 37852190172270 c5: 453960 Y0: 344517009720320657345668021520609 Y1: 870535396513771 rlim: 90000000 alim: 90000000 lpbr: 30 lpba: 30 mfbr: 61 mfba: 61 rlambda: 2.7 alambda: 2.7 Code:
lpba lpbr mfba mfbr r/alim (M) r/alambda Siever Rels_req (M) ETA (hrs) rel/spec_q 30 30 60 60 67 2.7 15e 92 4870 1.5655 30 30 60 60 67 2.7 15e 92 4870 1.5655 30 30 61 61 67 2.7 15e 92 4873 1.5655 30 30 60 60 75 2.7 15e 92 4939 1.5775 30 30 60 60 90 2.7 15e 92 4989 1.598 30 30 61 61 100 2.7 15e 92 5043 1.6115 30 30 61 61 111 2.7 15e 92 5087 1.623 31 30 62 61 111 2.7 15e 137 5531 2.3125 30 31 61 62 111 2.7 15e 137 5816 2.1625 31 31 62 62 111 2.7 15e 182 5840 3.091 30 30 61 61 67 2.7 14e 92 5899 0.7105 30 30 60 60 67 2.7 14e 92 5901 0.7105 30 30 60 60 75 2.7 14e 92 5979 0.715 30 30 60 60 90 2.7 14e 92 6206 0.7265 30 30 61 61 100 2.7 14e 92 6353 0.735 30 30 61 61 111 2.7 14e 92 6496 0.7415 30 30 61 61 111 2.7 16e 92 6691 3.4185 31 30 62 61 111 2.7 14e 137 6940 1.056 31 31 62 62 111 2.7 14e 182 7133 1.412 31 31 62 62 111 2.7 16e 182 7144 6.7215 30 31 61 62 111 2.7 14e 137 7346 0.992 Last fiddled with by swellman on 20130730 at 01:37 Reason: Formatting and clarification 

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