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Old 2016-07-15, 04:40   #2
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Uncwilly's Avatar
Aug 2003
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First and foremost, welcome to the search for Mersenne Primes! Hope you enjoy yourself.

Let's see if we can get you the answers are looking for:
Originally Posted by afjewkes View Post
I'm currently running a LL first test for an exponent - if this was to find a prime, would I get credit at the end of this test (which is up to 2^79 for this exponent) and then a potential award once it's been checked by over users?
So, you have selected to do a first time test on an exponent. You say that it has been taken (trial factored) to 2^79. Based upon this, I am guessing that you are working on an exponent in the 332M range (the 100 million decimal digit range.) You are hoping to be the one to find the first known 100 million digit prime. These tests take a long time on many machines. Credit for any assignment is only awarded when the results of the task are turned in. For LL tests, the whole test has to be completed to known the result and credit can not be properly awarded for incomplete results. For Trial Factoring, credit can be award for each bit level result that gets turned in or when a factor is found. For P-1, the credit can only be awarded when the test is complete or the factor is found.

If it is found to be prime on your machine, it will be double and triple checked on different kinds of machines using different programs written by different people. If all of these show that it is prime, then process of pursuing the EFF award starts.

Another question, I'm running an exponent on a slower PC that seems to be taking 53 times longer? And in prime95 it says stage 1 is x% complete, how many stages are there?
53 times longer than what? If you are working on an exponent in the 332M range, these take ~5,000 GHz-days worth of work to do an LL test on.

Stage 1: This makes me think that your machine is doing P-1 factoring. This and TF are done before LL testing to check for factors. With these test we can eliminate over 60% of the exponents by finding factors. It is a wise investment of time to take the numbers to certain bit levels and P-1 bounds before LL testing. P-1 has 2 stage with each of these having 2 phases. Once P-1 is complete, then the LL test will start. If an exponent has previously had enough TF and P-1 done on it, Prime95 will start the LL directly.

Last fiddled with by Uncwilly on 2016-07-15 at 04:43
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