20211227, 08:27  #1 
"Shivam"
Dec 2021
India
9_{16} Posts 
Can someone really help me understand how to get started with this?
Hi i'm a newbie to GIMPS, would really appreicate if someone helps me understand how to get going with things over here?
I also have a bit hard time using PRIME 95, let me be a part of you guys as well. THANKS AND REGARDS 
20211227, 08:30  #2 
"Shivam"
Dec 2021
India
3^{2} Posts 
Can someone really help me understand how to get started with this?
hey, im so sorry to bring this up out of nowhere but can someone really help me understand how to get started with this? I'm new to GIMPS and have quite a bit issues understanding prime95.
Thanks 
20211227, 12:13  #3  
"Viliam Furík"
Jul 2018
Martin, Slovakia
2F1_{16} Posts 
Quote:
But I am not Kriesel, so I will also tell you some things directly: Prime95 can do the following (and more, but pretty much only these things are sensible for a general user):  LL and PRP tests of Mersenne numbers, that look for primes. LL, LucasLehmer test, if computed without any error, decides whether it's prime or not. To account for the occasional errors we do another run of the same test called "doublecheck" to make sure that the result is as correct as it can be under some assumptions of correctness about the program used  there are/were sometimes faulty chips that are/were widespread, e.g. the Pentium bug (I, however, don't know the specifics, as I wasn't aware of GIMPS back then, and possibly not even born yet  quick googling confirms I was not amongst the living yet) which make the computations bad, because in the best case they will be performed absolutely correctly on the software side, but on equally bad hardware, which would produce the exact same results, despite them being incorrect. There were also faulty programs (any Mersenneoriented program, so the CPU and GPU ones together), a lot more often than hardware, I think. PRP tests are similar, basically identical in time required, but they have few differences other than the obvious difference in name caused by the different tests being used, namely they are PRobable Prime tests, which means (assuming no errors) that if it says the number is not prime, it is not prime for sure, and if it says that it is a prime, it almost certainly the case, but to be sure, LL tests are run to confirm the primality of the Mersenne number; they allow us to easily verify their correctness without running them again by doing few specific computations along the way and making a proof file, that goes on to verification, and if all is good, it guarantees there were no errors during the test, and the result is correct  whatever the result is, it is correct, so not prime is not prime, and a prime result should be verified by LL.  P1 factoring is done to find factors of Mersenne numbers that are relatively easy to find. If a factor is found, the need for a test is gone, because it is obviously not prime.  PRPCF and ECM: PRPCF is a PRP test done on Mersenne numbers with some factors, that determines whether there are any remaining factors to be found, or whether the last chunk (a cofactor) is a probable prime (same behavior as with normal PRP, but you can't use LL tests for these). ECM is another way of factoring Mersenne numbers. There is also one big category of work, trial factoring, which should be done on GPUs because CPUs are much better with LL and PRP, and it is basically a waste of time to do TF with them, as GPUs are in most cases more than 100 times faster at it. That's about it. Feel free to ask about anything. 

20211227, 13:03  #4 
"TF79LL86GIMPS96gpu17"
Mar 2017
US midwest
2·17·191 Posts 
The reference info is a collection I've been working on for years. It started as what I would have liked to have found already available for getting started in GPU GIMPS computing, when I joined the forum years ago, and has expanded to book size, and covering GPU, CPU, and cloud GIMPS computing. It has been iterated upon frequently and will be further in the future as things change (proof generation being a recent example), as people ask questions which aren't quite covered yet, errors are identified, etc. Newcomers play a vital role in improving it, providing new eyes to find gaps and errors, and bringing new perspectives and questions
Viliam did a fine job of describing common work types for searching for new Mersenne primes. (But not in time order.) The sequence for a given exponent is (assuming prime95 or mprime is in use):
A concept to learn about early is the category structure in the assignment rules. Assignment rules for first time PRP are not stated but are more or less the same as for LL that are stated there. Last fiddled with by kriesel on 20211227 at 13:06 
20211227, 22:19  #5  
If I May
"Chris Halsall"
Sep 2002
Barbados
5·7·13·23 Posts 
Quote:
Few appreciate how important curation at this level of detail is. Well done sir. Sincerely. 

20211227, 22:53  #6 
"/X\(‘‘)/X\"
Jan 2013
2^{3}·3^{2}·41 Posts 

20211228, 01:01  #7  
"TF79LL86GIMPS96gpu17"
Mar 2017
US midwest
2·17·191 Posts 
Quote:
Quote:
After initially developing the beginnings of the reference info for my own use, it made no sense to hoard it. It is the better for many eyes on it. I occasionally get a helpful PM pointing out where I got something wrong, omitted something, or content has become outdated. Documentation is something I can do, so our amazing programmers can do what they do best, perhaps spending less time on user questions and documentation, allowing a little more on code development. Thanks all for the kind words of encouragement, and also for what you do for the project. And note the many people credited with contributing in some way at the bottom of the reference info's monster table of contents page (at Viliam's link above). 

20211228, 01:14  #8 
"Viliam Furík"
Jul 2018
Martin, Slovakia
753_{10} Posts 

20211228, 02:14  #9  
"TF79LL86GIMPS96gpu17"
Mar 2017
US midwest
14536_{8} Posts 
Quote:
Last fiddled with by kriesel on 20211228 at 02:36 

20211228, 09:09  #10  
"Shivam"
Dec 2021
India
3^{2} Posts 
Prime95
Quote:
Can you please tell that among the test option given on the Prime95 software which one has the most probability of finding a Mersenne prime? Currently I'm running World Record Sized Numbers To Prime Test. Also I'm not able to create more than 1 worker Regards 

20211228, 13:54  #11  
Feb 2017
Nowhere
5786_{10} Posts 
Quote:
There is AFAIK no way to tell in advance which prime exponents p are "more likely" to produce Mersenne primes than others. If anyone involved in the project knew, they'd already be on it. Given that a total 51 Mersenne primes have been found, with all prime exponents to well over 100 million having been tested at least once, it should be clear that the chances of finding a Mersenne prime are exceedingly small. If your primary motive in participating in the project is to discover a Mersenne prime, you are almost certainly doomed to disappointment, especially if your computing resources are limited. There is a great deal of work available in eliminating candidates  trial factoring (TF) and P1 eliminate candidates by finding small factors. 

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