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 2009-09-12, 13:54 #848 fivemack (loop (#_fork))     Feb 2006 Cambridge, England 2·3,191 Posts An honest-to-someone ECM miss 10-7.191 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)
2009-09-14, 15:57   #849
Joe O

Aug 2002

3×52×7 Posts

Quote:
 Originally Posted by fivemack 10-7.191 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)
Are you saying that
1) not enough ECM was run on this number?
2) the ECM program is faulty?
3) something else?

 2009-09-14, 16:13 #850 fivemack (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.
2009-09-14, 18:26   #851
R.D. Silverman

Nov 2003

22·5·373 Posts

Quote:
 Originally Posted by fivemack 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.
No, I would say that this is the accepted usage of "ECM miss".

2009-09-16, 06:50   #852
Andi47

Oct 2004
Austria

46628 Posts
7,2,247+

Quote:
 Originally Posted by Andi47 Do I get this right, a difficulty-193-SNFS would take approx. as long as a 193*0.69 = 133-digit GNFS and thus would be in range for home computing?
Seems that this one didn't have much ECM (unfortunately, the reservation page doesn't give information about the amount of ECM done on each number).

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

2009-09-16, 07:00   #853
xilman
Bamboozled!

"𒉺𒌌𒇷𒆷𒀭"
May 2003
Down not across

295B16 Posts

Quote:
 Originally Posted by Andi47 Seems that this one didn't have much ECM (unfortunately, the reservation page doesn't give information about the amount of ECM done on each number). 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
All the numbers in the ECMnet server have essentially the same amount of work done on them, that being the allocation strategy set up.

At the moment, the server is about half-way 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

2009-09-16, 11:44   #854
Joe O

Aug 2002

3·52·7 Posts

Quote:
 Originally Posted by fivemack 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.
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.

 2009-09-16, 17:52 #855 yoyo     Oct 2006 Berlin, Germany 2·3·101 Posts Should I run some ECM curves via yoyo@home on it? yoyo
 2009-09-17, 17:16 #856 unconnected     May 2009 Russia, Moscow 43·59 Posts 7^299-6^299 c183=p43*p140 p43=1895196682008094522046817009226083917957561 by ECM
 2009-09-17, 20:40 #857 Yamato     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 (((((9^203-8^203)/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
2009-09-17, 22:50   #858
fivemack
(loop (#_fork))

Feb 2006
Cambridge, England

2×3,191 Posts

Quote:
 Originally Posted by yoyo Should I run some ECM curves via yoyo@home on it? yoyo
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 CPU-years of ECM at them might be inappropriate.

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