20210825, 10:36  #1 
"James Heinrich"
May 2004
exNorthern Ontario
3,793 Posts 
pretest option minimum size
When I run through a set of numbers I want to factor I usually start with the pretest option (to sift out the easy factorizations, I can continue the hard ones later), but sometimes yafu finds a small composite during ECM that could easily be factored in a few seconds but the pretest option prevents siqs from running. What I'd like to see is some option like "pretest_threshold <digits>" where siqs is allowed to run on composites less than <digits> digits.

20210825, 13:34  #2  
"Ben"
Feb 2007
E32_{16} Posts 
Quote:


20210825, 13:56  #3 
"James Heinrich"
May 2004
exNorthern Ontario
3793_{10} Posts 
No, nothing is lost, I just want to get the small ones done first.
As a random example (edited for brevity): Code:
Starting factorization of 14156161707358647804728644991232561131993674306133067594227858606703236064990613537256494257288902246641757583573171692305069299841687536 div: found prime factor = 2 div: found prime factor = 2 div: found prime factor = 2 div: found prime factor = 2 div: found prime factor = 3 div: found prime factor = 271 div: found prime factor = 1831 scheduled 30 curves at B1=2000 toward target pretesting depth of 43.00 prp13 = 2893511660873 (curve 4 stg2 B1=2000 sigma=303770396 thread=0) Finished 4 curves using Lenstra ECM method on C129 input, B1=2K, B2=gmpecm default Finished 26 curves using Lenstra ECM method on C117 input, B1=2K, B2=gmpecm default Finished 74 curves using Lenstra ECM method on C117 input, B1=11K, B2=gmpecm default Finished 216 curves using Lenstra ECM method on C117 input, B1=50K, B2=gmpecm default pm1: starting B1 = 3750K, B2 = gmpecm default on C117 prp29 = 32895160657610218397548809017 (curve 40 stg2 B1=250000 sigma=303537196 thread=0) Finished 240 curves using Lenstra ECM method on C117 input, B1=250K, B2=gmpecm default prp28 = 3347338785154139067312669731 (curve 30 stg2 B1=250000 sigma=1688092289 thread=2) Finished 180 curves using Lenstra ECM method on C88 input, B1=250K, B2=gmpecm default final ECM pretested depth: 30.44 c61 cofactor = 1865476249140792141927330175598826930439956399426237147045167 Total factoring time = 90.5932 seconds 
20220505, 15:30  #4 
"James Heinrich"
May 2004
exNorthern Ontario
3,793 Posts 
Just following up on this request  is this likely to be included in an upcoming version?
Just in case my idea isn't clear, (my understanding of) the current logic is something crudely like: Code:
while (ECM_LEVEL_T_LEVEL < UNFACTORED_DIGITS * ECM_RATIO) { doECMandPM1(); } if (COFACTOR_IS_COMPOSITE) { if (OPTION_PRETEST) { // give up, output composite cofactor } else { doSIQSorNFS(COFACTOR); } } Code:
if (OPTION_PRETEST && (OPTION_PRETEST < UNFACTORED_DIGITS)) { // give up, output composite cofactor } else { doSIQSorNFS(COFACTOR); } Does that make sense? 
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