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-   -   New Project: Amicable Numbers (https://www.overclock.net/forum/365-overclock-net-boinc-team/1622474-new-project-amicable-numbers.html)

 bfromcolo 02-04-2017 08:47 AM

A new math project to find amicable numbers.

https://sech.me/boinc/Amicable/

If you were wondering what an amicable number is, from Wikipedia:

Amicable numbers are two different numbers so related that the sum of the proper divisors of each is equal to the other number. (A proper divisor of a number is a positive factor of that number other than the number itself.

The smallest pair of amicable numbers is (220, 284). They are amicable because the proper divisors of 220 are 1, 2, 4, 5, 10, 11, 20, 22, 44, 55 and 110, of which the sum is 284; and the proper divisors of 284 are 1, 2, 4, 71 and 142, of which the sum is 220.

Not sure these have much more value than trillion digit primes, but its something to crunch for WUProp stars.

 Tex1954 02-04-2017 02:34 PM

Well, I put one setup on it to see what it's about...

 tictoc 02-04-2017 03:03 PM

The tasks for this project are multi-threaded.  It will be interesting to see how they perform. I have completed 4 tasks so far.  The run-times are pretty similar, but the points vary.

 Run time (sec) CPU time (sec) Credit 3,512.95 17,522.73 816.96 3,602.06 17,962.75 943.09 3,585.81 17,880.21 1,566.90 3,956.17 19,732.88 1,097.92

 bfromcolo 02-04-2017 03:50 PM

Trying to make space in one of my systems to try this out, looking on their boards you can control the number of CPUs used by an individual task through the app config:

Quote:

```<app_config>
<app>
<name>amicable_2_64</name>
<max_concurrent>1</max_concurrent>
</app>
<app_version>
<app_name>amicable_2_64</app_name>
<plan_class>mt</plan_class>
<avg_ncpus>15.000000</avg_ncpus>
</app_version>
</app_config>
```

 Tex1954 02-05-2017 12:47 AM

4,278.75 33,967.68 1,032.98
3,904.71 31,003.49 1,256.10
3,823.44 30,391.79 1,275.44
4,007.67 31,852.80 1,434.43

These on a setup using 8T of E3-1240V2 CPU.

 bfromcolo 02-05-2017 05:12 AM

I have finished 4 of them, using 5 cores on a 6300 (stock), Mint 17.3.  7850 sec run times, 39000 sec of CPU time, but all tasks are still pending credit.

WUProp seems to be smart enough to measure CPU time for run time in this case, or run time times cores.  The only other multi-core project I remember running was Atlas and in that case WUProp looked at run time and not the number of cores involved.

 k4m1k4z3 02-05-2017 09:04 AM

I will fire this up on one of my laptops for a while. I have too many projects I want to run and not enough CPU cores... Perhaps I will have to build another 2P when my bonus check arrives in a few months

 BeerCan 02-05-2017 01:06 PM

Just so I know, what the heck is this research good for? Anyone know?

 bfromcolo 02-05-2017 01:19 PM

Quote:
Originally Posted by BeerCan

Just so I know, what the heck is this research good for? Anyone know?

As far as I know it just finds amicable number pairs up to 2^64, and there probably isn't much application for them.  Although Wikipedia says they may have mystical powers, it also says there are over 1B known pairs, so I don't know it the ones this project is finding have been found before or are new ones.

https://en.wikipedia.org/wiki/Amicable_numbers

 Tex1954 02-05-2017 11:04 PM

Quote:
Originally Posted by bfromcolo

As far as I know it just finds amicable number pairs up to 2^64, and there probably isn't much application for them.  Although Wikipedia says they may have mystical powers, it also says there are over 1B known pairs, so I don't know it the ones this project is finding have been found before or are new ones.

https://en.wikipedia.org/wiki/Amicable_numbers

Umm, JUST? 1 x 2^64 is a MUCH higher number than 1 x 10^18... I think it will take a while...

And like many math projects, especially PRIME projects, they climb that arithmetic mountain "Because It's There!" and for no other practical reason I can ascertain....

LOL!

PS: This about all I am going to do, two are pending... I may give a couple to the 2P setup just for grins later...

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