Welcome to the Solar Eclipse Challenge

The fourth Challenge of the 2017 Challenge series is a 3 day challenge to celebrate the Solar eclipse of August 21, 2017. The challenge is being offered on the Generalized Cullen/Woodall Prime Search (LLR) application.

On Monday, August 21, 2017, a total solar eclipse will be visible in totality within a band across the entire contiguous United States. It will only be visible in other countries as a partial eclipse. The previous time a total solar eclipse was visible across the entire contiguous United States was on June 8, 1918.

A solar eclipse occurs when the moon passes between earth and the sun, thereby totally or partly obscuring the image of the sun for a viewer on Earth. A total solar eclipse occurs when the moon's apparent diameter is larger than the sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

Not since the February 1979 eclipse has a total eclipse been visible from the mainland United States. The path of totality will touch 14 states, though a partial eclipse will be visible in many more states. The event will begin on the Oregon coast as a partial eclipse at 9:06 a.m. PDT on August 21, and will end later that day as a partial eclipse along the South Carolina coast at about 4:06 p.m. EDT. Many total eclipse viewing events are planned http://www.americaneclipse2017.org/eclipse-events/.

To participate in the Challenge, please select only the Generalized Cullen/Woodall Prime Search (LLR) project in your PrimeGrid preferences section. The challenge will begin 20th August 2017 18:00 UTC and end 23rd August 2017 18:00 UTC.

Application builds are available for Linux 32 and 64 bit, Windows 32 and 64 bit and MacIntel. Intel CPUs with AVX capabilities (Sandy Bridge, Ivy Bridge, Haswell, Broadwell, Skylake, Kabylake) will have a very large advantage, and Intel CPUs with FMA3 (Haswell, Broadwell, Skylake, Kabylake) will be the fastest.

ATTENTION: The primality program LLR is CPU intensive; so, it is vital to have a stable system with good cooling. It does not tolerate "even the slightest of errors." Please see this post for more details on how you can "stress test" your computer. Tasks will take ~16 hours on fast/newer computers and 24+ hours on slower/older computers. If your computer is highly overclocked, please consider "stress testing" it. Sieving is an excellent alternative for computers that are not able to LLR. :)

Highly overclocked Haswell, Broadwell, Skylake, or Kabylake (i.e., Intel Core i7, i5, and i3 -4xxx or better) computers running the application will see fastest times. Note that GCW is running the latest FMA3 version of LLR which takes full advantage of the features of these newer CPUs. It's faster than the previous LLR app and draws more power and produces more heat. If you have a Haswell, Broadwell, Skylake, or Kabylake CPU, especially if it's overclocked or has overclocked memory, and haven't run the new FMA3 LLR before, we strongly suggest running it before the challenge while you are monitoring the temperatures.

Please, please, please make sure your machines are up to the task.

Time zone converter:

The World Clock - Time Zone Converter

NOTE: The countdown clock on the front page uses the host computer time. Therefore, if your computer time is off, so will the countdown clock. For precise timing, use the UTC Time in the data section to the left of the countdown clock.

Scoring Information

Scores will be kept for individuals and teams. Only tasks issued AFTER 20 August 2017 18:00 UTC and received BEFORE 23 August 2017 18:00 UTC will be considered for credit. We will be using the same scoring method as we currently use for BOINC credits.
A quorum of 2 is NOT needed to award Challenge score - i.e. no double checker. Therefore, each returned result will earn a Challenge score. Please note that if the result is eventually declared invalid, the score will be removed.


At the Conclusion of the Challenge

We kindly ask users "moving on" to ABORT their tasks instead of DETACHING, RESETTING, or PAUSING.

ABORTING tasks allows them to be recycled immediately; thus a much faster "clean up" to the end of an LLR Challenge. DETACHING, RESETTING, and PAUSING tasks causes them to remain in limbo until they EXPIRE. Therefore, we must wait until tasks expire to send them out to be completed.

Please consider either completing what's in the queue or ABORTING them. Thank you. :)

About the Generalized Cullen/Woodall Prime Search

A Cullen number (first studied by Reverend James Cullen in 1905) is a number of the form n * 2^n + 1. A Woodall number (first studied by Allan Cunningham and H.J. Woodall in 1917) is a number of the form n * 2^n - 1.

Generalized Cullen and Woodall numbers are of the form n * b^n + 1 and n * b^n - 1, respectively, where n + 2 > b.

PrimeGrid recently moved its search for Generalized Cullen and Generalized Woodall primes from PRPNet to BOINC. A double-check of all ranges searched by PRPNet has been completed by PrimeGrid, and is continuing on with new work running multiple bases (b values) concurrently and incrementing through n values.

PrimeGrid is sieving to a much larger n than has been previously done. The largest candidates will be in excess of 15,000,000 digits, and will be the same size as the largest candidates in the Seventeen or Bust project.

Once PrimeGrid finds a Generalized Cullen or Woodall on a base, it stops looking for Generalized Cullen or Woodall primes on that base, depending on the type found. For all the current bases, PrimeGrid will initially be searching only for Generalized Cullen Primes. For detail about the bases PrimeGrid will be searching (and has searched), you can go here: http://www.primegrid.com/forum_thread.php?id=3008&nowrap=true#30718.

In addition to having found the largest known Cullen prime http://primes.utm.edu/primes/page.php?id=89536 and largest known Woodall prime http://primes.utm.edu/primes/page.php?id=83407, PrimeGrid has found the largest known Generalized Cullen prime, http://primes.utm.edu/primes/page.php?id=122349 and the 4th largest known Generalized Woodall prime http://primes.utm.edu/primes/page.php?id=98862.

For more information on Generalized Cullen and Woodall Numbers, you can go here: http://primes.utm.edu/top20/page.php?id=42 and here: http://primes.utm.edu/top20/page.php?id=45.

What is LLR?

The Lucas-Lehmer-Riesel (LLR) test is a primality test for numbers of the form N = k*2^n − 1, with 2^n > k. Also, LLR is a program developed by Jean Penne that can run the LLR-tests. It includes the Proth test to perform +1 tests and PRP to test non base 2 numbers. See also:

• Lucas-Lehmer-Riesel test (WIKI)
  
• Download LLR by Jean Penné
  

(Edouard Lucas: 1842-1891, Derrick H. Lehmer: 1905-1991, Hans Riesel: 1929-2014).
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I am new to PrimeGrid.
I have agreed to use some of the spare time of my computer to help the process of finding new prime numbers.

Since I started to help in the quest, my copmuter is continually humming. Is the hard drive in continuous use or is the cooling fan trying to cool the ele3ctrics?

Does the Solar Eclipse have some influence on the detection of prime numbers?

What other natural occurances have some influence on the detection of prime numbers?

The challenge will begin 20th August 2017 18:00 UTC

however, it mentions that

Only tasks issued AFTER 20 August 2017 08:00 UTC

will be considered for credit towards the challenge. Should these two times match each other, or are they correct as stated?

A typo has occurred ... Both times should read 18:00UTC

GO GO GO!
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My lucky number is 75898^524288+1
Please do not PM me with support questions. They will usually go unanswered. Ask on the forums instead. Thank you!

GO GO GO!

GO GO GO!

Is it okay to stop a task midways and turn the -t4 parameter on? Does it continue fine, or will it corrupt / fail / w.e?

I'm not 100% sure. If I had to guess, I'd say LLR would work fine. I don't know how BOINC will treat it.

If it's a challenge task, you've only been running it for a few minutes and have very little to lose if it clobbers the tasks.

You can do some research on these forums from earlier this year. I *think* that if you change app_config to use -t 4 and also set the correct field to tell BOINC that 4 cpus are used, and then restart BOINC, it will start running them 1 at a time on 4 cores. But I have not tried it myself. I recall reading that others had tried this and it worked. Worst case scenario is you lose a couple of hours work, but you get more time running challenge tasks.
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My lucky number is 75898^524288+1
Please do not PM me with support questions. They will usually go unanswered. Ask on the forums instead. Thank you!

By the way, the results currently showing up on the leaderboard won't last. They're not valid. Something got borked and those two tasks completed in a couple of minutes and didn't upload a result file. Once the the wingmen come in and the validator runs, they'll be removed from the leaderboard.
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My lucky number is 75898^524288+1
Please do not PM me with support questions. They will usually go unanswered. Ask on the forums instead. Thank you!

Also I saw that AVX512 should be on mainstream and server CPUs later this year. How much will that improve LLR runtime?

Also I saw that AVX512 should be on mainstream and server CPUs later this year. How much will that improve LLR runtime?

AVX-512 is here now in Skylake-X. It will make exactly zero difference in the short term as we need software to be updated to use it. In theory it could offer doubling of performance per clock, but apparently the few things that actually use it really heats things up, so it might not be that simple. There is also talk that ram bandwidth limiting may be more of a problem than ever.

A bunch of the more serious coders over there collectively bought a system to test on.

I vaguely recall a response along the line of don't hold your breath when asked about AVX512 timescales, but don't quote me on that.

It was "only" a 70% eclipse here, but we had surprisingly good weather, and I had ordered a package of eclipse glasses a while ago when they were still easy to get. I shared them with all the neighbors on the block, and we had a grand time watching the sun get blotted out from the sky.
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My lucky number is 75898^524288+1
Please do not PM me with support questions. They will usually go unanswered. Ask on the forums instead. Thank you!

A few hours late due to me being outside staring at the sun...

The statistics after day 1:


Challenge: Solar Eclipse
App: 30 (GCW-LLR)
(As of 2017-08-21 19:37:41 UTC)

19413 tasks have been sent out. [CPU/GPU/anonymous_platform: 19372 (100%) / 0 (0%) / 41 (0%)]

Of those tasks that have been sent out:

1575 (8%) came back with some kind of an error. [1575 (8%) / 0 (0%) / 0 (0%)]
4846 (25%) have returned a successful result. [4812 (25%) / 0 (0%) / 34 (0%)]
12992 (67%) are still in progress. [12985 (67%) / 0 (0%) / 7 (0%)]

Of the tasks that have been returned successfully:

2903 (60%) are pending validation. [2878 (59%) / 0 (0%) / 25 (1%)]
1909 (39%) have been successfully validated. [1900 (39%) / 0 (0%) / 9 (0%)]
9 (0%) were invalid. [9 (0%) / 0 (0%) / 0 (0%)]
25 (1%) are inconclusive. [25 (1%) / 0 (0%) / 0 (0%)]

The current leading edge (i.e., latest work unit for which work has actually been sent out to a host) is n=3343081. The leading edge was at n=3236988 at the beginning of the challenge. Since the challenge started, the leading edge has advanced 3.28% as much as it had prior to the challenge!

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My lucky number is 75898^524288+1
Please do not PM me with support questions. They will usually go unanswered. Ask on the forums instead. Thank you!

It looks like we've found a GCW prime. More details once it's verified, etc.
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My lucky number is 75898^524288+1
Please do not PM me with support questions. They will usually go unanswered. Ask on the forums instead. Thank you!