Hello fellow prime number hunters.

[zampa]

Hello everyone, zampa here. I'm new but I hope I'll be old here soon. :)

So today I watched the numberphile episode where Matt Parker spoke about a prime found here. So i figured I have my computer on quite a bit and I'd be happy to contribute.

There are a few things I wonder. Before I continue I should list my computer specs.
Intel Core i5-4690K @ 3.50GHz
Asus GeForce GTX 970 Strix
Corsair Vengeance Pro DDR3 2x8GB

I got my very first assignmest which was of work type D (LL double-check, primality test, assigned as 2nd or 3rd LL test).

Now that does not tell me very much what sort of priority that is or how 'important' that run is (I read somewhere that weaker computers get different assignment that those with fast ones)

And I was just curious since I'm not sure I'll be able to run very long calculations (lasting several days) I wondered if I could assign/be assigned shorter or 'less improtant' ones. So I know I'll atleast finish what I started.

Cheers!

[TObject]

Double check assignments are exactly that. One computer has already run a test and determined that the number is not prime.

But, what if that computer made a mistake? That is why we run the test a second time and compare results. Sometimes (rarely) results mismatch; in that case we run the test again and again until two computers agree. There is very small chance that the first computer made a mistake and the number is prime.

First time tests have statistically higher probability of finding a prime, but they run much longer; as the faster smaller numbers have already been tested.

Completing a few double checks is a good way to verify your hardware is working properly, before moving to other types of assignments. Nothing wrong with staying with double check tests ether, many of machines I configured run nothing but double checks.

Welcome and enjoy!

[Uncwilly]

Your computer can be useful even if you don't have it on all of the time.

The reason that you got a double-check for your first assignment is:
1. We double check all numbers to verify that there was not a test with an error. When identical results are reported, we can be sure that the number is not prime.
2. We need to check the computers before giving out longer tests. If a machine is bad, the whole test is wasted. The sooner that this can be checked the better.

All of the test types are important in their own way. Some find factors, this is faster than running the LL test and proves the number is not prime. LL and DC are the same test. It is important that each number gets checked twice (on 2 different machines). If a number is reported as Prime, it gets checked on several different machines running different programs to prove that no single computer made and error. (We have had this happen before and the software was updated to prevent the problem from reoccurring.)

The software will automatically save and restart tests when you shut off the machine. This allows it to resume a very long test. Each computer can be given an assignment that is good for the machine, how much it runs (on average), and adjusted for where we are in the project. A machine that was the best 10 years ago is not so good now and the project is dealing with larger numbers. The server takes these factors into account when handing out assignments.

Welcome to the group. Hope you have fun.

[zampa]

I see, well since I don't actually care that much if I find a prime, I just want to do my part and contribute so I guess I'll just stick to double-checking all the time then, thanks!

[TObject]

Your GeForce GTX 970 is good for trying to find factors of the exponents before running LL tests. If a factor is found—the number is not prime; so no need to run the lengthy test.

Start here on how to use your GPU:
http://mersenneforum.org/showthread.php?t=16140

[CRGreathouse]

Welcome!

Looks like you have a fine computer, good for whatever kind of work you want to do.

Originally Posted by zampa

I got my very first assignmest which was of work type D (LL double-check, primality test, assigned as 2nd or 3rd LL test).

Now that does not tell me very much what sort of priority that is or how 'important' that run is (I read somewhere that weaker computers get different assignment that those with fast ones)

It depends on what you want to do!

The project considers (for good reasons) numbers to be known as composite when they've been checked and double-checked (with matching residues). So if you want to push the wavefront forward, possibly helping mathematicians understand the distribution of Mersenne primes, then double-checking is the thing for you.

If you want to be especially careful, or if you like short-running tests, then you might do triple-checking in addition (or instead).

If you want even shorter assignments, and especially if you have lots of RAM (as you do), then P-1 makes sense. There's also a greater sense of accomplishment in that you can find factors much more easily than new Mersenne primes.

Finally, sieving is a good use of a GPU like yours.

Since you said you don't want long-running tests first-time isn't for you. (It's good for people who like to dream of finding the next Mersenne prime, though!)