20111019, 08:58  #1 
"Nathan"
Jul 2008
Maryland, USA
5·223 Posts 
Mfaktc keeps going after a factor is found
Not sure if this is intended or not, but whenever mfaktc finds a factor in the middle of a bit level, it does not immediately stop and begin the next assignment (as Prime95 would); rather, it continues on to the end of the bit level, as if no factor were found.

20111019, 10:11  #2 
"Oliver"
Mar 2005
Germany
2^{3}·139 Posts 
Hi,
works as expected. check mfaktc.ini: Code:
# possible values for StopAfterFactor: # 0: Do not stop the current assignment after a factor was found. # 1: When a factor was found for the current assignment stop after the # current bitlevel. This makes only sense when Stages is enabled. # 2: When a factor was found for the current assignment stop after the # current class. StopAfterFactor=1 
20111019, 15:37  #3 
May 2011
Orange Park, FL
38A_{16} Posts 
I was glad it kept going....
M602249941 has a factor: 86439049638640106399
M602249941 has a factor: 77482243219676340503 M602249941 has a factor: 22781228486416840393 found 3 factor(s) for M602249941 from 2^64 to 2^67 [mfaktc 0.17Win barrett79_mul32] In this sort of unusual case I was glad it kept going. Chuck 
20111019, 19:49  #4 
Nov 2002
Anchorage, AK
3·7·17 Posts 
If you set, StopAfterFactor=2, it will stop after the current class, but the output would read (notice the (partially tested)):
Code:
M490287241 has a factor: 23617822113724688119 found 1 factor(s) for M490287241 from 2^64 to 2^66 (partially tested) [mfaktc 0.17Win barrett79_mul32] Code:
M490287241 has a factor: 23617822113724688119 M490287241 has a factor: 19751191822676004343 found 2 factor(s) for M490287241 from 2^64 to 2^66 [mfaktc 0.17Win barrett79_mul32] Last fiddled with by delta_t on 20111019 at 19:50 
20120407, 08:25  #5 
Mar 2012
Germany
32_{8} Posts 

20120407, 11:35  #6 
Mar 2010
110011011_{2} Posts 
Nope.
Other mersenne numbers may be divisible by that factor, iirc. 
20120407, 13:33  #7 
May 2011
Orange Park, FL
1612_{8} Posts 
After I joined GPU272, I changed the setting to stop when a factor is found. When I was doing those very high 600M TFs it only took a short time to check one, but now that I am working in the 59M range it takes 5 1/2 hours for each test, so it seems smarter to stop when a factor is found.

20120407, 14:47  #8 
Jun 2003
2·3·17·53 Posts 

20120407, 16:33  #9 
Mar 2010
3·137 Posts 

20120407, 16:44  #10 
Oct 2011
7×97 Posts 
Since a factor was found, it is safe to stop as you have disproved primality. If your goal is full factorization, letting it continue could add another factor.
Last fiddled with by bcp19 on 20120407 at 16:44 Reason: spelling 
20120407, 17:04  #11 
Jun 2003
151E_{16} Posts 
Unless you want to find the smallest factor for a given number (which is midly interesting, mathematically speaking).
Last fiddled with by axn on 20120407 at 17:05 
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