mersenneforum.org 69 * 2^n - 1
 Register FAQ Search Today's Posts Mark Forums Read

 2014-01-14, 22:50 #23 Kosmaj     Nov 2003 2×1,811 Posts Hi diep, Yes, there is a jump in the length of the used FF transform, from about 144k to 160k, at n=2750k. The next jump to 192k will appear at n=3274k.
 2014-01-14, 23:06 #24 diep     Sep 2006 The Netherlands 11×71 Posts Ah many thanks! So the next jump makes it extra tough to find stuff of 1M digits :) After a slow start first few months, it's 16 cores now which went steady, yet i guess i soon have to increase that to 32+ cores to keep the momentum because of the huge slowdowns. Too bad i can't throw into battle the gpu's yet. Know a description of how it works with this fft len size and the used transform? I have a book from Pomerance & Crandall, yet those descriptions are not very usable to write code from and so far it seems one of the few books at least attempting to describe something :) The FFT i implemented a few years ago, it works in a power of 2 larger. So to calculate n limbs one needs an array sized 2n limbs, which simply would mean a single 8 core box is same speed like 1 GPU, instead of the GPU being roughly 5x faster (Tesla C2075's i have here) or more than a single 8 core Xeon box here :)
 2014-01-15, 11:27 #25 pinhodecarlos     "Carlos Pinho" Oct 2011 Milton Keynes, UK 10011011111012 Posts Hi diep, I found this: 69*2^2428251-1 is prime! (730979 decimal digits) Time : 2077.484 sec. HEHEHEHEHEHE
 2014-01-15, 14:06 #26 diep     Sep 2006 The Netherlands 11×71 Posts Congratulations!
 2014-01-15, 14:14 #27 diep     Sep 2006 The Netherlands 11×71 Posts Did you finish it now to 2.5M? As i started at 2.5M as appointed. It's testing to 3M here now in the current batch. Last fiddled with by diep on 2014-01-15 at 14:15
2014-01-15, 14:48   #28
pinhodecarlos

"Carlos Pinho"
Oct 2011
Milton Keynes, UK

3·1,663 Posts

Quote:
 Originally Posted by diep Did you finish it now to 2.5M? As i started at 2.5M as appointed. It's testing to 3M here now in the current batch.
It is a RPS drive, I am not testing it alone.

 2014-01-15, 14:53 #29 diep     Sep 2006 The Netherlands 11·71 Posts Maybe you find another few primes there, let's hope so! As for 69, note after this 2.41M find i hadn't expected in the range till 3M for another 2 at least to be there! I thought: "maybe there is one around 2.8Mbit". Yet already 2 showed up now :) Last fiddled with by diep on 2014-01-15 at 14:55
 2014-04-15, 23:23 #30 diep     Sep 2006 The Netherlands 11×71 Posts Last cores will take some time to finish yet 3M nearly completed. Divided 3M-4M into pieces. Cores already busy short while there. Maybe the gem shows up as the last to be checked! All machines being equipped with ECC is tough to blame on a bitflip in RAM :) If the crashed internet machine here fixed and other IT stuff might have look at CUDA again for doing Riesel with it.
 2014-05-09, 22:30 #31 diep     Sep 2006 The Netherlands 11·71 Posts Prime! 69 * 2 ^ 3097340 - 1 is prime Please can one or more try to verify? Thanks, Vincent
 2014-05-09, 23:25 #32 pinhodecarlos     "Carlos Pinho" Oct 2011 Milton Keynes, UK 10011011111012 Posts If you trust your hardware just submit it. Only within an hour I will have an open slot to test this number.
 2014-05-09, 23:25 #33 paulunderwood     Sep 2002 Database er0rr 2×7×281 Posts Code: 69*2^3097340-1 is prime! Time : 2579.994 sec. Well done!

All times are UTC. The time now is 14:00.

Thu Dec 2 14:00:40 UTC 2021 up 132 days, 8:29, 0 users, load averages: 1.93, 1.60, 1.49