mersenneforum.org Create a new assignment
 Register FAQ Search Today's Posts Mark Forums Read

 2022-01-25, 13:17 #1 tait1k27   Feb 2020 7 Posts Create a new assignment How to create a new trial factor assignment with $$M_p$$ in Prime95, where $$M_p$$ is a composite number Last fiddled with by tait1k27 on 2022-01-25 at 13:20
2022-01-25, 14:07   #2
kriesel

"TF79LL86GIMPS96gpu17"
Mar 2017
US midwest

7×877 Posts

Quote:
 Originally Posted by tait1k27 How to create a new trial factor assignment with $$M_p$$ in Prime95, where $$M_p$$ is a composite number
Well, for GIMPS prime finding purposes, or efficiency, don't.
If you already know M(p)=2p-1 is composite, it's already ruled out as the next Mp discovery.
If it's the exponent that's composite, there are easily found algebraic factors for the corresponding Mn.
TF is so much faster on GPUs that it's a waste of a CPU to do TF in prime95.
If the exponent is so large (>232) that a GPU app such as mfakto or mfaktx can't be used, it's also further beyond prime95's capabilities.
From prime95's "whatsnew.txt":
Quote:
 Prime95 should not be used for trial factoring. GPUs are over 10 times more efficient at that task.
Some newer GPUs are up to ~5 bits (~40 times) more effective at TF than at P-1 or PRP.
These and much more are covered in the reference info collection.

Last fiddled with by kriesel on 2022-01-25 at 14:20

 Similar Threads Thread Thread Starter Forum Replies Last Post sp00n y-cruncher 1 2021-03-24 12:51 jkr442 Teams 3 2012-11-22 12:19 Fox_McCloud_123 Information & Answers 2 2012-05-04 23:25 ET_ PrimeNet 12 2008-11-03 22:11 DPRGI-Fab Teams 1 2004-02-19 22:22

All times are UTC. The time now is 23:43.

Fri Jan 28 23:43:31 UTC 2022 up 189 days, 18:12, 1 user, load averages: 1.32, 1.37, 1.45