20090912, 13:54  #848 
(loop (#_fork))
Feb 2006
Cambridge, England
2·3,191 Posts 
An honesttosomeone ECM miss
107.191 S191 (152) [14e/27lp/2^23sp] (1048428s + 336s + 11837s@4CPU + 1478s/2)
Fri Sep 11 20:08:31 2009 prp42 factor: 602042088775639986918297776645429449546619 Fri Sep 11 20:08:31 2009 prp110 factor: 33929634886978114141291477425365580390751852643524199226349853412013173286258912284088108701389099986638761717 (a million seconds is nearly 2*p45, and the factor's only a p42) 
20090914, 15:57  #849  
Aug 2002
3×5^{2}×7 Posts 
Quote:
1) not enough ECM was run on this number? 2) the ECM program is faulty? 3) something else? 

20090914, 16:13  #850 
(loop (#_fork))
Feb 2006
Cambridge, England
2·3,191 Posts 
I tend to use 'ECM miss' to mean 'if I'd run ECM instead of snfs, I would have found the factor more quickly'; I appreciate this is probably not the normal use of the term.

20090914, 18:26  #851 
Nov 2003
2^{2}·5·373 Posts 

20090916, 06:50  #852  
Oct 2004
Austria
4662_{8} Posts 
7,2,247+
Quote:
Yesterday, I just thought to give it a try and run a bunch of curves on it overnight, and... Code:
Run 110 out of 500: Using B1=11000000, B2=35133391030, polynomial Dickson(12), sigma=4183249465 Step 1 took 237281ms Step 2 took 62016ms ********** Factor found in step 2: 2349783051111976239049347232722196704029 Found probable prime factor of 40 digits: 2349783051111976239049347232722196704029 Probable prime cofactor 1541091246548990353689435982710386631762710119356152870973958183688458251235091483146681989184564163537618914925796259 has 118 digits 

20090916, 07:00  #853  
Bamboozled!
"πΊππ·π·π"
May 2003
Down not across
295B_{16} Posts 
Quote:
At the moment, the server is about halfway through handing out curves with B1=3M, so the expected size of factors to be found will be around 40 digits or perhaps a little less. That the p40 factor above has not yet been found by the ECMnet clients is not at all surprising. Paul 

20090916, 11:44  #854 
Aug 2002
3·5^{2}·7 Posts 
But even at 2*P45 there would be a ~14% probability of missing a 45 digit factor. It might have taken a lot more curves, and cpu time.

20090916, 17:52  #855 
Oct 2006
Berlin, Germany
2·3·101 Posts 
Should I run some ECM curves via yoyo@home on it?
yoyo 
20090917, 17:16  #856 
May 2009
Russia, Moscow
43·59 Posts 
7^2996^299
c183=p43*p140 p43=1895196682008094522046817009226083917957561 by ECM 
20090917, 20:40  #857 
Sep 2005
Berlin
2×3×11 Posts 
Some more factors...
Code:
Run 172 out of 1000: Using B1=3000000, B2=5706890290, polynomial Dickson(6), sigma=664469849 Step 1 took 11192ms ********** Factor found in step 1: 16329409528242736979240605668734636153 Found probable prime factor of 38 digits: 16329409528242736979240605668734636153 Probable prime cofactor (((((9^2038^203)/407353462746867001)/298093771407041)/6233803301928460803553)/4555386192335572300559213161)/16329409528242736979240605668734636153 has 75 digits Run 27 out of 1000: Using B1=3000000, B2=5706890290, polynomial Dickson(6), sigma=2682735469 Step 1 took 20494ms Step 2 took 8464ms ********** Factor found in step 2: 524451880982120622418669944269190199223 Found probable prime factor of 39 digits: 524451880982120622418669944269190199223 Probable prime cofactor ((8^257+5^257)/(13*5746950733*38434462212856815594943*1258221908128778009146226401))/524451880982120622418669944269190199223 has 133 digits 
20090917, 22:50  #858 
(loop (#_fork))
Feb 2006
Cambridge, England
2×3,191 Posts 
There's already an ecmnet server (port 8194 on the machine 83.143.57.194) set up with these numbers in; I think to some extent they're intended as a gentle introduction for the NFS methods, and throwing CPUyears of ECM at them might be inappropriate.

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