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Old 2011-10-19, 08:58   #1
NBtarheel_33
 
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"Nathan"
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Default 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.
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Old 2011-10-19, 10:11   #2
TheJudger
 
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"Oliver"
Mar 2005
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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
Oliver
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Old 2011-10-19, 15:37   #3
Chuck
 
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Default 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 0.17-Win barrett79_mul32]

In this sort of unusual case I was glad it kept going.

Chuck
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Old 2011-10-19, 19:49   #4
delta_t
 
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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 0.17-Win barrett79_mul32]
As with Chuck, I'm glad I didn't have it set to =2 as that exponent had two factors in the tested range.

Code:
M490287241 has a factor: 23617822113724688119
M490287241 has a factor: 19751191822676004343
found 2 factor(s) for M490287241 from 2^64 to 2^66 [mfaktc 0.17-Win barrett79_mul32]
Some like to make sure the bit range is tested through instead of partially.

Last fiddled with by delta_t on 2011-10-19 at 19:50
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Old 2012-04-07, 08:25   #5
MikeBerlin
 
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Quote:
Originally Posted by Chuck View Post
... I was glad it kept going....Chuck
But why, I dont understand, why it make sense to test a mersenne after finding a factor. In my opinion it's only lost time, isnĀ“t it?
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Old 2012-04-07, 11:35   #6
Karl M Johnson
 
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Nope.
Other mersenne numbers may be divisible by that factor, iirc.
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Old 2012-04-07, 13:33   #7
Chuck
 
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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.
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Old 2012-04-07, 14:47   #8
axn
 
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Quote:
Originally Posted by Karl M Johnson View Post
Nope.
Other mersenne numbers may be divisible by that factor, iirc.
Nope. No other mersenne numbers will be divisible by that factor.
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Old 2012-04-07, 16:33   #9
Karl M Johnson
 
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Quote:
Originally Posted by axn View Post
Nope. No other mersenne numbers will be divisible by that factor.
So there's no real point in continuing a TF job after a factor was found ?
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Old 2012-04-07, 16:44   #10
bcp19
 
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Quote:
Originally Posted by Karl M Johnson View Post
So there's no real point in continuing a TF job after a factor was found ?
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 2012-04-07 at 16:44 Reason: spelling
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Old 2012-04-07, 17:04   #11
axn
 
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Quote:
Originally Posted by Karl M Johnson View Post
So there's no real point in continuing a TF job after a factor was found ?
Unless you want to find the smallest factor for a given number (which is midly interesting, mathematically speaking).

Last fiddled with by axn on 2012-04-07 at 17:05
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