20120314, 11:39  #12 
Basketry That Evening!
"Bunslow the Bold"
Jun 2011
40<A<43 89<O<88
3·2,399 Posts 
See Brian's post above; keep in mind that as he said, current exponents handed out by PrimeNet are much higher than M47. (M47 would take 89 days on one core of an Intel Core i72600K slightly overclocked, and something in the 55M58M range as you're likely to get from PrimeNet would probably take 33.5 weeks.)

20120315, 04:34  #13 
"Jason Goatcher"
Mar 2005
5·701 Posts 
Possibly stupid question, but have we found 47 Mersennes? It sounds like the person doesn't speak English as a first language, so might not sufficiently understand what the Prime95 program does.

20120315, 04:43  #14 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
2^{3}×7×163 Posts 
You remind of a nerdy anecdote:
Einstein, Newton and Pascal were playing hideandgoseek. It was Einstein's turn to seek, and as he began counting Pascal ran and hid behind a bush. But Newton picked up a stick, used it to draw a metre square on the ground, and sat in the middle of it. Einstein finished counting, turned around, and immediately said "Aha! Found you Newton." but Newton replied "Ah, but a newton per a metre squared is a pascal! 
20120315, 06:22  #15  
Romulan Interpreter
Jun 2011
Thailand
10001010100111_{2} Posts 
Quote:
@Batalov: ROFL, you made my day... hehehe... Last fiddled with by LaurV on 20120315 at 06:23 

20120315, 08:08  #16  
4,787 Posts 
Quote:
Is there anybody thinking I am searching for the Mr. Mersenne or the Mersenne number, not for the Mersenne prime? 

20120315, 11:58  #17  
"Forget I exist"
Jul 2009
Dumbassville
8369_{10} Posts 
Quote:
Last fiddled with by science_man_88 on 20120315 at 11:58 

20120315, 17:05  #18 
Basketry That Evening!
"Bunslow the Bold"
Jun 2011
40<A<43 89<O<88
1110000011101_{2} Posts 

20120318, 03:32  #19 
Dec 2010
Monticello
3260_{8} Posts 
OK, a little more detail:
"smaller" Mersenne numbers (less than 2^10,000,0001) or so have ECM curves run on them that sometimes find factors. These are relatively quick; a few hours apiece...for a few percent chance of finding a factor. Around 2^27,000,000 or so, begin a large number of Mersenne numbers that have been reported as composite by a single LucasLehmer test. Some of us work that range of exponents, since the chance of a computer hardware error in such long LucasLehmer tests is up to a few percent, depending on just how hard your hardware is being pushed. These are the "double checks". There's also trial factoring; to do this effectively, you need a GPU running CUDA or OpenCL. These cards outperform CPUs on this job by 100:1. Trial Factoring (TF) eliminates numbers from LL(LucasLehmer) tests by finding factors; these can run in an hour or two, but it may take a day or three to find a factor, and the problem gets exponentially harder as the bit level goes up. Then there's P1 testing. This is a sophisticated factoring method that can find factors of a certain form, and can run for several days on a given exponent, with typically 37% chance of finding a factor on a typical primenet assignment. Such assignments run a day or two. Around 2^50,000,0001 or so are the first time LL tests. If you are really nuts, you can have your PC spend a year or more completing a test around 2^333,333,333 in the search for the first 100million digit prime number. But it's not for the faint of heart; the probability of an error in your calculations goes up another order of magnitude or two, making errors a near certainty. Since noone else has said it, unregistered user, I will: Your efforts on behalf of primenet are appreciated, whatever part of the problem you decide to set your computer(s) to working on, however casually. Thank you for joining GIMPS and contributing. Last fiddled with by Christenson on 20120318 at 03:38 Reason: Two very important words: Thank you. 
20120318, 03:40  #20 
Basketry That Evening!
"Bunslow the Bold"
Jun 2011
40<A<43 89<O<88
7197_{10} Posts 
Heh, so many bad word choices/terrible puns...
A few notes: The first time LL tests are closer to 2^55,000,0001 or 2^60,000,0001, and depending on the particular settings, I can usually do a P1 in less than a day. What is most useful for GIMPS is P1, at the moment, which gets the least work relative to the other work types. You do however need (typically) at least 1GiB of RAM available to do that. If you don't want to do that, then just do either first time primality tests (LL tests) or double checks. At the moment, less double checking goes on compared to first time tests, so some of us prefer to work on those instead. (Because the double check exponents are ~ half the size of first time tests, they run 45 times faster.) 
20120318, 12:05  #21  
2^{4}·3^{2}·11 Posts 
Quote:


20120319, 02:05  #22 
"Lucan"
Dec 2006
England
6451_{10} Posts 

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