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Old 2009-06-17, 09:24   #1
spyros
 
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Default prime 95 notation

hello i am new in this forum
i get "trial factoring M58707931 to 2^69 x% complete" messages
what M58707931 to 2^69 standard notation is?
thank you
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Old 2009-06-17, 10:28   #2
spyros
 
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trial factoring is giving me messages like M58703971 to 2^69 is x%complete. what is the meaning of this?
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Old 2009-06-17, 10:49   #3
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Quote:
Originally Posted by spyros View Post
trial factoring is giving me messages like M58703971 to 2^69 is x%complete. what is the meaning of this?
Don't you know what the % symbol means?
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Old 2009-06-17, 12:00   #4
spyros
 
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i am asking what is the meaning of "M58703971 to 2^69"?

Last fiddled with by spyros on 2009-06-17 at 12:14
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Old 2009-06-17, 12:06   #5
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I'll break it down:
Trial factoring means dividing by many small numbers to see if any divide the large number. For more info about how the number is quickly divided (among other GIMPS-related mathematics) see http://v5www.mersenne.org/various/math.php
M58707931 means 2^58707931-1. For general info on Mersenne numbers see Mersenne prime
2^69 means 2 times itself 69 times.

So "trial factoring M58707931 to 2^69" means we're dividing 2^58707931-1 by every number between 2^68 and 2^69 (the numbers below 2^68 have already been checked) to see if any divide the number exactly. If any do, then we know that the number is not prime.
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Old 2009-06-17, 12:38   #6
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Quote:
Originally Posted by Mini-Geek View Post
So "trial factoring M58707931 to 2^69" means we're dividing 2^58707931-1 by every number between 2^68 and 2^69 (the numbers below 2^68 have already been checked)
all potential factors
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Old 2009-06-17, 12:40   #7
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Quote:
Originally Posted by spyros View Post
i am asking what is the meaning of "M58703971 to 2^69"?
Your answer has been given in the thread that you started.
http://www.mersenneforum.org/showthread.php?p=177872
go there for the answer.
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Old 2009-06-17, 12:50   #8
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i see.
There may be other prime numbers between merssenne primes?
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Old 2009-06-17, 12:59   #9
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258707931-1 might be prime. The first check is testing all numbers up to a certain limit to see if they are a factor of 258707931-1.

Then Prime95 does a longer test called P-1 to test for larger factors, and finally if we still don't know any factors, Prime95 starts the long primality test which is called Lucas-Lehmer test (LL test).

Last fiddled with by ATH on 2009-06-17 at 13:03
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Old 2009-06-17, 13:08   #10
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Quote:
Originally Posted by spyros View Post
There may be other prime numbers between merssenne primes?
There are other primes between merseenes. It is just that checking mersennes is so very much easier than checking other numbers that size.
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Old 2009-06-17, 13:11   #11
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Quote:
Originally Posted by ATH View Post
258707931-1 might be prime. The first check is testing all numbers up to a certain limit to see if they are a factor of 258707931-1.
Again all potential factors of the given prime ar checked (up to the size mentioned). If you see the math section referenced above, you will see that any pontential factor is a function of the exponent (58707931 in your case), this makes it easier to check for factors.
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