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drummerslowrise

1)
Message boards :
Number crunching :
Ideas for 2023 Challenge Lineup?
(Message 158099)
Posted 2 days ago by Jay
Lesser known Mathematician: Alexander Abian (January 1, 1923 – July 24, 1999).
http://www.scientificlib.com/en/Mathematics/Biographies/AlexanderAbian.html
Promoted a theory that blowing up the moon would eliminate natural disasters on earth as well as the seasons. Compared himself to Galileo when his theories were criticized.
A 28 day challenge might be appropriate.

2)
Message boards :
General discussion :
Thought for the day
(Message 156658)
Posted 118 days ago by Jay
I think I am a 70 size in Roman Numerals  2XL  but I will refrain from insisting to order them in this way. I haven't gotten that right have I? LXX? Ah! Is 2XL a number in Roman Numerals?
You're correct that 70 would be LXX in roman numerals.
Assuming 2XL transforms to XXL, then no, that is not a proper number in roman numerals. It could be understood to be 30, but the proper way to write 30 is XXX.

3)
Message boards :
Number crunching :
System with problems
(Message 156280)
Posted 141 days ago by Jay
All three hosts hold a big number of tasks, have many errored tasks and present zero Valid (or Pending) tasks. So they are in fact not contributing anything.
They acquire a bunch of tasks without ever correctly completing any. So we might just ignore them. Their "net effect" is that the tasks are sent to the productive hosts in a more irregular fashion.
I'd agree that in general it's ok to ignore them. However, I would assume the intent of the owners of these machines is to be contributing. I know if I was burning electricity and not doing anything productive I wouldn't be pleased. So personally, I'd appreciate someone reaching out to let me know.
And assuming they intend to be contributing, I'd welcome the contributions to the project.
That said, I'm not going to spend the time to try and find contact information, if it's not readily available.

4)
Message boards :
Number crunching :
World Water Day Challenge
(Message 154923)
Posted 250 days ago by Jay
The choice of any user to be a part of or change a team is a personal one, and unless their is some other rule violation (e.g., an obscene team name, etc.), any PG participant should feel free to be a part of any team that allows them to be a member, change their team affiliation any time they like, or choose not to be a member of a team.
If a team doesn't want a member to change to a different team, then be the best possible team. That's a good strategy for recruiting new members as well. How a user measures or determines "best" will likely be different for every individual.

5)
Message boards :
General discussion :
Thoughts with any and all in or near Ukraine
(Message 154541)
Posted 277 days ago by Jay
I don't know if there are any Primegrid members in or around Ukraine, but if so, I hope you and those you care about, are safe and remain so.

6)
Message boards :
Sierpinski/Riesel Base 5 Problem :
Riesel k=3622 eliminated (outside PrimeGrid)
(Message 154452)
Posted 279 days ago by Jay
Since we work from the bottom up, when we find a prime, nearly all the work to prove it's the lowest prime is already done. All that's necessary is to finish off the candidates that are already in the process of being tested. Little to no extra work is required.
However, when someone else finds a prime at a much higher N than where we're testing, a substantial amount of work would be required to prove it's the lowest prime. We're not doing that.
It's the same for all the conjectures.
That makes sense. Thanks for the extra info!

7)
Message boards :
Sierpinski/Riesel Base 5 Problem :
Riesel k=3622 eliminated (outside PrimeGrid)
(Message 154442)
Posted 280 days ago by Jay
Yes. Our goal is to prove the conjecture. For Ks that we eliminate, we will continue to prove that those are the lowest primes. Ks eliminated by other people won't be tested by us.
When PrimeGrid eliminates a K, does proving it's the lowest prime go to the lowest of the priority list? Seems like those are resources that could be used to eliminate the next K. Proving it's the lowest has nothing to do with the conjecture. Could that work be postponed for a separate subproject? Or is the amount of work left to prove it's the smallest prime something like less than 23 days worth?
Is the same strategy applied to SOB? I'm in this to prove conjecture(s). I'd rather be on the front lines of the attack.

8)
Message boards :
Problems and Help :
Is there a table or chart that shows the optimal CPU cache for each project?
(Message 154018)
Posted 294 days ago by Jay
The way I understand it is that FFT sizes need to get bigger when you do tests on bigger numbers. This is to keep the required accuracy so the result does not have errors. There are some sweet spot FFT sizes which is what gets used.
As for buying a CPU, generally I wouldn't worry about it unless you really intend to optimise PrimeGrid work over all else. Even then, you can consider which projects you're interested in. Running a task fast is not the same as getting the most tasks done in a given time.
That's exactly what I do hope to do.
Yes, FFT increases with bigger numbers being tested. I focus on SOB tasks. Based on the chart posted earlier I'm looking at 3932160*8 = 31,457,280. I'm going to round up and call it 32 MB per task.
Maybe I can find a processor with 32 MB and it will be adequate for todays tasks. But what happens when FFT increases? First question is how much does it increase at a time? Will the next increase bump it up to 33 MB? Or will the next increase bump it up to 36 MB? or double it to 64 MB? Or something else? I assume those "sweet spot FFT sizes" are known. What's the next one? What are the next 20?
If that information is known, the next question is how often does FFT increase? Does it increase with each individual task? Does it increase when tasks double in size? Will the next "sweet spot FFT size" come into play when tasks are just a bit bigger than they are now, or not until they are a lot bigger than now?
I understand that I'm concerned with future happenings. I also know that making predictions is difficult (especially about the future). Which is why I'm hoping there is a chart of FFT vs time, or a general rule that someone can look at and interpolate from. Can I say FFT doubles every month? Every year? Every 3 years? etc.
Then I can say I'll likely need XXX MB L3 cache to fit the tasks expected for the next Y years. Then I can look at cpu's and select one based on that info.

9)
Message boards :
Problems and Help :
Is there a table or chart that shows the optimal CPU cache for each project?
(Message 154008)
Posted 295 days ago by Jay
It changes over time as the task sizes change.
...
That being said, here's the current (maximum) FFT sizes for active LLR tasks. Multiply these numbers by 8:
+++
 project  max(fft_size) 
+++
 321  1048576 
 CUL  2359296 
 ESP  2359296 
 GCW  2621440 
 MEG  262144 
 PPSE  131072 
 PPS  262144 
 PSP  2949120 
 SGS  131072 
 SOB  3932160 
 SR5  983040 
 TRP  1310720 
 WOO  2293760 
+++
How does FFT change? I assume it doesn't increase by 1. Is there any record over time of FFT sizes that could be used to interpolate future growth?
When I purchanse a new machine I don't want just get something that is adequate for right now, but something that will have enough cache for the near future FFT sizes as well.

10)
Message boards :
Generalized Fermat Prime Search :
Guess the number of digits in the LAST GFN17LOW prime
(Message 153608)
Posted 305 days ago by Jay
While I haven't done much with GFN (I focused on other projects and left these tasks for all of you) it's really cool to me to be able to say a project has been completed. Lets wrap up SOB next.

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