20140121, 16:57  #67 
"Tapio Rajala"
Feb 2010
Finland
3^{2}×5×7 Posts 

20160829, 13:36  #68  
Sep 2003
29·89 Posts 
Reviving an old thread from 2013, since the deadline is now almost exactly a month away.
From the first post in this thread: Quote:
Nearly three years have passed, and it looks like Professor Guy's $20 is doomed. I think there are two methods to try to find factors of Fermat numbers. One is sort of the equivalent of trial factoring (searching ranges of N and k). The FermatSearch subforum has details for reserving ranges. I'm not sure what software is used for that. The other method is ECM testing, using mprime/Prime95. F12 is now at the stage where ECM testing is looking for factors in the range of about 65 digits (about 215 bits). Each curve takes about 3.1 hours on a 2.3 GHz Haswell architecture. F13 is now at the stage where ECM testing is looking for factors in the range of about 60 digits (about 200 bits). Each curve takes about 1.7 hours on a 2.3 GHz Haswell architecture. Finding a new factor would be interesting in its own right, albeit rather improbable since you might have to run tens of thousands of curves or even hundreds of thousands before you hit a factor at this level, if one even exists. And even then, saving Professor Guy from financial ruin would require the cofactor to be prime as well. Nevertheless, in case anyone wants to make a token effort, here are some lines you could add to your worktodo.txt (requires stopping the program first, or to avoid having to do that, just create a worktodo.add file that the program will automatically read and append to worktodo.txt the next time it does a disk write). There are 10 curves for F12 (2^{4096}+1) and 18 curves for F13 (2^{8192}+1), so maybe 30 hours of CPU time for each on a modern Haswell machine. F12 needs 535MB of memory in stage two, and F13 needs 579MB. Code:
ECM2=1,2,4096,1,800000000,80000000000,10,"114689,26017793,63766529,190274191361,1256132134125569,568630647535356955169033410940867804839360742060818433" ECM2=1,2,8192,1,260000000,26000000000,18,"2710954639361,2663848877152141313,3603109844542291969,319546020820551643220672513" Last fiddled with by GP2 on 20160829 at 13:40 

20160829, 14:30  #69  
Banned
"Luigi"
Aug 2002
Team Italia
2^{2}·1,193 Posts 
Quote:


20160829, 19:29  #70 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
2^{3}×5×229 Posts 
Luigi, can you keep the desperate appeal alive by reposting it on fermatsearch.org ?
Now, both W.Keller's site and prothsearch joined the choir invisible. Shuffled off their mortal coil, ran down the curtain. Their metabolic processes are now 'istory! 
20160830, 08:26  #71 
Banned
"Luigi"
Aug 2002
Team Italia
2^{2}·1,193 Posts 

20160830, 09:55  #72 
"Carlos Pinho"
Oct 2011
Milton Keynes, UK
4773_{10} Posts 
Maybe contact yoyo. What would be the ecm standalone client flags?
EDIT: I want to help or using Prime95 or using ecm. For Prime95 I only want to use 2 of the 4 cores available from my laptop but I need someone to support me on getting the worktodo.txt setup or the prime.ini (not sure about the file names). For ecm what are the command lines I need to setup to run some curve on those two Fermat numbers. Last fiddled with by pinhodecarlos on 20160830 at 10:02 
20160830, 10:01  #73 
Banned
"Luigi"
Aug 2002
Team Italia
2^{2}·1,193 Posts 

20160830, 10:05  #74 
"Carlos Pinho"
Oct 2011
Milton Keynes, UK
3·37·43 Posts 

20160830, 10:29  #75 
"Carlos Pinho"
Oct 2011
Milton Keynes, UK
3·37·43 Posts 
Here's my doubt.
worktodo.txt content Code:
[Worker #1] ECM2=1,2,4096,1,800000000,80000000000,1000,"114689,26017793,63766529,190274191361,1256132134125569,568630647535356955169033410940867804839360742060818433" [Worker #2] ECM2=1,2,4096,1,800000000,80000000000,1000,"114689,26017793,63766529,190274191361,1256132134125569,568630647535356955169033410940867804839360742060818433" Code:
OldCpuSpeed=2864 NewCpuSpeedCount=0 NewCpuSpeed=0 RollingAverage=1000 RollingAverageIsFromV27=1 ComputerGUID=ec875508223b69f7b24450ba96978009 WorkerThreads=2 Affinity=100 ThreadsPerTest=2 Carlos 
20160830, 10:43  #76 
Sep 2003
101000010101_{2} Posts 

20160830, 13:14  #77 
Jun 2003
2^{2}·5·239 Posts 
I think it might be ever so slightly more efficient to use a B2/B1 multiplier of 200, since that gives roughly equal times for stage 1 & 2 (which should be optimal according to RDS).
Anyone care to compute the expected curves for both configuration and see whether it makes any difference? 
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