As a mechanical engineering student, I love approximating pi. Don't get me wrong, I'm a huge fan of the infinite non-repeating(?) digits, but they have a way of muddling up a tidy back-of-the-napkin calculation. I tend to be a proponent of 𝝿≈3 (and 𝝿≈1 is also really useful in a pinch), but I can appreciate the extra significant figures of 22/7.

What could be a better way to celebrate the quantum-guaranteed imprecision of the human experience, than with a 3-day challenge on the PPS-LLR subproject from 22 July 22:00 UTC to 25 July 22:00 UTC?

More details to follow!

In the meantime, here's some info about the previous 2022 Challenges:

Heptadecagenarian Challenge
World Water Day Challenge
Geek Pride Day Challenge
M.C. Escher's Birthday Challenge


____________

Time flies like an arrow. Fruit flies like a banana.

A week ago I bought myself a very cheap 2P (2x12c) Xeon server.

Er, I bought myself a very nice used computer case that happened to come with a 2P Xeon server inside. This is not the first time this has happened to me, either, though it is the first time I knew there was going to be a system included.

Anyway, it'll be all set up to run just in time to break it in with the challenge. Whoopee!

--------------

For those of you looking for a "should I multithread?" suggestion:

If you have less than 2MB of L3 cache per core (L2+L3 for Skylake-X/SP and newer HEDT/Xeon parts), running 2 threads/task will keep everything within the CPU. (You may still wish to test throughput for yourself, as YMMV).

2MB or more, 1 thread/task will treat you right.
____________
Eating more cheese on Thursdays.

3.14 days it is lol maybe.
Thanks guys

The Antikythera mechanism has a gear with 223 teeth. If it meshed with a gear having 71 teeth, it would produce an even closer approximation of Pi than 22/7.

The Antikythera mechanism has a gear with 223 teeth. If it meshed with a gear having 71 teeth, it would produce an even closer approximation of Pi than 22/7.

Lots of teeth - I don't know what I am trying to say, but less teeth could be good.

3 = 5. A pi approximation. It could be worse.

Welcome to the Pi Approximation Day Challenge!

The fifth challenge of the 2022 Series will be a 3-day challenge celebrating the day that our arbitrary measurement units for the Earth's rotation align to numerically resemble the fraction 22/7, which approximates the value of the infamous circle constant 'pi' with an error of 400ppm! Honestly, I'm not sure why March 14th gets all the love -- 3.14 is a much worse approximation for pi!

The challenge will be offered on the PPS-LLR application, beginning 22 July 22:00 UTC and ending 25 July 22:00 UTC. To participate in the Challenge, please select only the Proth Prime Search LLR (PPS) project in your PrimeGrid preferences section.

Note on LLR2 tasks: LLR2 has eliminated the need for a full doublecheck task on each workunit, but has replaced it with a short verification task. Expect to receive a few tasks about 1% of normal length.

Application builds are available for Linux 32 and 64 bit, Windows 32 and 64 bit and MacIntel. Intel and recent AMD CPUs with FMA3 capabilities (Haswell or better for Intel, Zen-2 or better for AMD) will have a very large advantage, and Intel CPUs with dual AVX-512 (certain recent Intel Skylake-X and Xeon CPUs) will be the fastest.

Note that LLR is running the latest AVX-512 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, especially if they're highly overclocked. If you have certain recent Intel Skylake-X and Xeon CPUs, especially if it's overclocked or has overclocked memory, and haven't run the new AVX-512 LLR before, we strongly suggest running it before the challenge while you are monitoring the temperatures.

Multi-threading is supported and IS recommended for slower computers. (PPS tasks on one CPU core will take ~1 hour on fast/newer computers and 8 hours+ on slower/older computers.)

Those looking to maximize their computer's performance during this challenge, or when running LLR in general, may find this information useful.

• Your mileage may vary. Before the challenge starts, take some time and experiment and see what works best on your computer.
  
• If you have a CPU with hyperthreading or SMT, either turn off this feature in the BIOS, or set BOINC to use 50% of the processors.
  
  
  • If you're using a GPU for other tasks, it may be beneficial to leave hyperthreading on in the BIOS and instead tell BOINC to use 50% of the CPU's. This will allow one of the hyperthreads to service the GPU.

  
  

• The new multi-threading system is now live. Click here to set the maximum number of threads. This will allow you to select multi-threading from the project preferences web page. No more app_config.xml. It works like this:
  
  
  • In the preferences selection, there are selections for "max jobs" and "max cpus", similar to the settings in app_config.
    
  • Unlike app_config, these two settings apply to ALL apps. You can't chose 1 thread for SGS and 4 for SoB. When you change apps, you need to change your multithreading settings if you want to run a different number of threads.
    
  • There will be individual settings for each venue (location).
    
  • This will eliminate the problem of BOINC downloading 1 task for every core.
    
  • The hyperthreading control isn't possible at this time.
    
  • The "max cpus" control will only apply to LLR apps. The "max jobs" control applies to all apps.

  
  

• If you want to continue to use app_config.xml for LLR tasks, you need to change it if you want it to work. Please see this message for more information.
  
• Some people have observed that when using multithreaded LLR, hyperthreading is actually beneficial. We encourage you to experiment and see what works best for you.

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 at the very top, above the countdown clock.

Scoring Information

Scores will be kept for individuals and teams. Only tasks issued AFTER 22 July 22:00 UTC and received BEFORE 25 July 22:00 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 Proth Prime Search

The Proth Prime Search is done in collaboration with the Proth Search project. This search looks for primes in the form of k*2^n+1. With the condition 2^n > k, these are often called Proth primes. This project also has the added bonus of possibly finding factors of "classical" Fermat numbers or Generalized Fermat numbers. As this requires PrimeFormGW (PFGW) (a primality-testing program), once PrimeGrid finds a prime, it is then tested on PrimeGrid's servers for divisibility.

Our initial goal was to double check all previous work up to n=500K for odd k<1200 and to fill in any gaps that were missed. We have accomplished that now and have increased it to n=800K. PG LLRNet searched up to n=200,000 and found several missed primes in previously searched ranges. Although primes that small did not make it into the Top 5000 Primes database, the work was still important as it may have led to new factors for "classical" Fermat numbers or Generalized Fermat numbers. While there are many GFN factors, currently there are only about 275 "classical" Fermat number factors known. Current primes found in PPS definitely make it into the Top 5000 Primes database.

Once the 800K goal is reached, we may head to 1M before turning our focus to smaller k values and higher n values. For example, k<300 complete to n=2M, k<600 complete to n=1.5M and so on.

For more information about "Proth" primes, please visit these links:

• Proth Prime - The Prime Glossary
  
• Proth Prime - Wolfram MathWorld
  
• Proth Number - Wikipedia

About Proth Search

The Proth Search project was established in 1998 by Ray Ballinger and Wilfrid Keller to coordinate a distributed effort to find Proth primes (primes of the form k*2^n+1) for k < 300. Ray was interested in finding primes while Wilfrid was interested in finding divisors of Fermat number. Since that time it has expanded to include k < 1200. Mark Rodenkirch (aka rogue) has been helping Ray keep the website up to date for the past few years.

Early in 2008, PrimeGrid and Proth Search teamed up to provide a software managed distributed effort to the search. Although it might appear that PrimeGrid is duplicating some of the Proth Search effort by re-doing some ranges, few ranges on Proth Search were ever double-checked. This has resulted in PrimeGrid finding primes that were missed by previous searchers. By the end of 2008, all new primes found by PrimeGrid were eligible for inclusion in Chris Caldwell's Prime Pages Top 5000. Sometime in 2009, over 90% of the tests handed out by PrimeGrid were numbers that have never been tested. For 2010, we hope to complete our reservation to 800K and extend it to 1M.

PrimeGrid intends to continue the search indefinitely for Proth primes.

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
  

What is LLR2?

LLR2 is an improvement to the LLR application developed by our very own Pavel Atnashev and stream. It utilizes Gerbicz checks to enable the Fast DoubleCheck feature, which will nearly double the speed of PrimeGrid's progress on the projects it's applied to. For more information, see this forum post.
____________

Time flies like an arrow. Fruit flies like a banana.

I'll throw out 100, but I'm not really familiar with the current PPS expected-tasks-per-prime rate.
____________
Eating more cheese on Thursdays.

i'll guess 34
____________

41
____________
My lucky number is 6219*2^3374198+1

I'll take a calculated guess:

Of the tasks waiting, I expect about 104 primes
Of the tasks in progress, I expect about 3 primes
Of the current total of tasks, if they complete during the challenge, I guess we will find:

107 primes, of wich quite a few will be MegaPrimes :)

I'll take a calculated guess:

Of the tasks waiting, I expect about 104 primes
Of the tasks in progress, I expect about 3 primes
Of the current total of tasks, if they complete during the challenge, I guess we will find:

107 primes, of wich quite a few will be MegaPrimes :)

Not a MEGA challenge, my friend. Hope you just have plain old PPS selected.

A very optimistic crowd...we found 83 PPS Mega primes in the TdP this year, so I think our three day venture with primes just a bit below that size is going go be a little less fruitful than most guesses thus far.

I will guess 5 primes found in the challenge.

12 hours into the challenge, here are the stats:

Challenge: Pi Approximation Day
App: 10 (PPS-LLR)
Fast DC tasks are NOT included.
(As of 2022-07-23 10:15:34 UTC)

166421 tasks have been sent out. [CPU/GPU/anonymous_platform: 166421 (100%) / 0 (0%) / 0 (0%)]

Of those tasks that have been sent out:

523 (0%) were aborted. [523 (0%) / 0 (0%) / 0 (0%)]
45 (0%) came back with some kind of an error. [45 (0%) / 0 (0%) / 0 (0%)]
105456 (63%) have returned a successful result. [105489 (63%) / 0 (0%) / 0 (0%)]
60447 (36%) are still in progress. [60451 (36%) / 0 (0%) / 0 (0%)]

Of the tasks that have been returned successfully:

19264 (18%) are pending validation. [19297 (18%) / 0 (0%) / 0 (0%)]
86192 (82%) have been successfully validated. [86192 (82%) / 0 (0%) / 0 (0%)]
6 (0%) were invalid. [6 (0%) / 0 (0%) / 0 (0%)]
0 (0%) are inconclusive. [0 (0%) / 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=3305680. The leading edge was at n=3295530 at the beginning of the challenge. Since the challenge started, the leading edge has advanced 0.31% as much as it had prior to the challenge!
____________

Time flies like an arrow. Fruit flies like a banana.

I'll also go with 5. I think 10 and above is unrealistic.

I'll also go with 5. I think 10 and above is unrealistic.

10 have been found so far according to Discord, so the guesses will need to be larger.

Having failed so spectacularly, I think I will just watch from the sidelines!

I'll also go with 5. I think 10 and above is unrealistic.

but the server is having some problems and is way, way behind in processing the results. It will be a while before the primes are disclosed.

**VERY** IMPORTANT ANNOUNCEMENT

The administrators may need to end this challenge early, without notice. There's been unanticipated problems with the server, and it may not make it to 22:00. We therefore may end the challenge abruptly and without warning by shutting down the server until we can process the backlog.

If you're bunkering tasks until the last minute, you may not be able to return them during the challenge.

We apologize for any inconvenience this may cause.

Most unfortunate if it comes to pass! I'm guessing that "shutting down the server" means all subprojects will be impacted?

Regardless, it's my turn for a local heatwave to hit, so I've already NNT'd some of my systems early so as not to cook the house more than mother nature is.
____________
Eating more cheese on Thursdays.

Most unfortunate if it comes to pass! I'm guessing that "shutting down the server" means all subprojects will be impacted?

Regardless, it's my turn for a local heatwave to hit, so I've already NNT'd some of my systems early so as not to cook the house more than mother nature is.

They're trying to keep a disk drive from filling up. There's a bottleneck in processing the extra-large files returned from LLR2 and there's not enough storage space. I don't think it's "down" yet, maybe bouncing a bit... but highly unlikely to run without problems until the end of the challenge. Many are shutting down their crunchers, so the load has dropped a LITTLE bit...

It's not related to the database, and aborting unstarted tasks would help, yes.
____________
My lucky number is 75898⁵²⁴²⁸⁸+1

That's given me incentive to hit NNW as I've been struggling a bit with the heat. Was hoping to finish in a nice position but it isn't happening regardless.

Bummer, most of my completed tasks from the last 12 hours are still trying to upload.

A best ever challenge finish for me in 131st!
____________
My lucky number is 6219*2^3374198+1

Did they end the challenge early then?

Uploads of results (all results, not just PPS) have been disabled.

The next couple of days may be a little rough.
____________
My lucky number is 75898⁵²⁴²⁸⁸+1

Admins - thank you for your efforts running the challenge.

I hope you resolve the hardware issues successfully.

You might let us know if users doing only the check versions of PPS would help you process the results faster and reduce your disk space shortage.

The challenge is over! That was certainly eventful.

We completed a whopping 1,340,402 tasks (including doublechecks).

Sorry for the lack of daily updates, the circumstances made it difficult ;-)

Cleanup is starting now!
____________

Time flies like an arrow. Fruit flies like a banana.