mersenneforum.org Te$ting billion digit number$
 User Name Remember Me? Password
 Register FAQ Search Today's Posts Mark Forums Read

 2019-06-23, 21:56 #1 paulunderwood     Sep 2002 Database er0rr 64138 Posts Te$ting billion digit number$ With the EFF award in mind, I am running this program: Code: forprime(q=1,100000000000,s=Mod(1416317954,q);for(k=7,33,s=s^2-2;if(s==2,print([q,k-2]);break))) [2, 5] [3, 5] [7, 5] [31, 5] [97, 5] [127, 7] [607, 5] [8191, 13] [12289, 10] [22783, 8] [131071, 17] [265471, 8] [524287, 19] [592897, 8] [1310719, 18] [21757951, 18] [29687809, 14] [39845887, 21] [665972737, 10] [708158977, 6] [2147483647, 31] [2210398207, 22] [2543310079, 8] [58133053441, 23] [60651732991, 21] I am interested in the penultimate result because it has "k-2=23". How long would it take an average AVX2 box to test it as a Mp? It has ~20 billion digits. (Note that 97 is there because k starts at 7.) Last fiddled with by paulunderwood on 2019-06-23 at 22:09
2019-06-23, 22:29   #2
GP2

Sep 2003

2,579 Posts

Quote:
 Originally Posted by paulunderwood How long would it take an average AVX2 box to test it as a Mp? It has ~20 billion digits.
You're gonna need a bigger box.

 2019-06-23, 23:26 #3 a1call     "Rashid Naimi" Oct 2015 Remote to Here/There 22×3×5×31 Posts This thread reminds me of a very old Sci-Fi novel that I never read myself but was told about by a friend: Person A: They have spaceships that can travel to the Moon. Person B: That's impossible. The power required for such a trip is enormous. Person A: Yes, but they are using steam-engines to power their ships. Last fiddled with by a1call on 2019-06-23 at 23:27
2019-06-23, 23:54   #4
chalsall
If I May

"Chris Halsall"
Sep 2002
Barbados

918910 Posts

Quote:
 Originally Posted by a1call Person A: Yes, but they are using steam-engines to power their ships.
Please forgive me for this, but I read The Mote in God's Eye as a child.

I fail to understand why SETI listens for low-band microwaves when higher frequency photons are more likely to be used for long distant communications.

Maybe I'm just stupid. A non-zero probably.

 2019-06-24, 00:39 #5 a1call     "Rashid Naimi" Oct 2015 Remote to Here/There 22·3·5·31 Posts At the risk of further off tracking, I agree that SETI is based on assuming the ET to have mastered capabilities that we did not possess a mere 200 years ago such as radio communication as well as Amplitude-Modulation which is only one of the many different possibilities of using electromagnetic waves, Yes there are more probable means than used by SETI. But that's a Can-of-Worms best left unopened in a Wikipedia-Obsessed, Democratically-Dictated-Science, audience.
 2019-06-24, 01:24 #6 paulunderwood     Sep 2002 Database er0rr 333910 Posts One more datum: Code: [87075848191, 21] Its corresponding Mp is composite.
 2019-06-24, 06:09 #7 paulunderwood     Sep 2002 Database er0rr 32·7·53 Posts Code: ? p=58133053441;for(k=1,1000000000,if(Mod(2,2*k*p+1)^p==1,print(k))) ? ## *** last result computed in 25min, 51,820 ms. The exponent has 36 bits. Both mlucas and mprime are limited to something below this. Can GPUs handle the trial factoring?
2019-06-24, 06:30   #8
R. Gerbicz

"Robert Gerbicz"
Oct 2005
Hungary

3×461 Posts

Quote:
 Originally Posted by paulunderwood The exponent has 36 bits. Both mlucas and mprime are limited to something below this. Can GPUs handle the trial factoring?
Surely, ~64 bits mutliplication isn't that hard, when there are existing gpu codes that are multiplying multimillion bits numbers.

2019-06-24, 06:43   #9
hansl

Apr 2019

5·41 Posts

Quote:
 Originally Posted by paulunderwood Code: ? p=58133053441;for(k=1,1000000000,if(Mod(2,2*k*p+1)^p==1,print(k))) ? ## *** last result computed in 25min, 51,820 ms. The exponent has 36 bits. Both mlucas and mprime are limited to something below this. Can GPUs handle the trial factoring?
Dunno about GPU apps, but factor5 can handle it. I checked up to 74bits
already and no factors.

Your code above is up to ~66.6bits
Code:
? log(2*1000000000*58133053441+1)/log(2)
%1 = 66.655992491035654326600824278847640961
Edit: no factor to 2^75

Last fiddled with by hansl on 2019-06-24 at 07:09

2019-06-24, 07:16   #10
paulunderwood

Sep 2002
Database er0rr

32×7×53 Posts

Quote:
 Originally Posted by hansl Dunno about GPU apps, but factor5 can handle it. I checked up to 74bits already and no factors. Your code above is up to ~66.6bits Code: ? log(2*1000000000*58133053441+1)/log(2) %1 = 66.655992491035654326600824278847640961 Edit: no factor to 2^75
I am testing 76 to 77 bits

 2019-06-24, 07:27 #11 hansl     Apr 2019 5·41 Posts OK, i'm ~70% done with 75-76. And I've started 77-78 and 78-79 on other boxes. BTW, I can't wait to upgrade one of my workstations. I recently ordered parts to take it from 6C/12T up to (dual socket) 24C/48T ... 4x the cores edit: No Factor from 75-76 bits. Last fiddled with by hansl on 2019-06-24 at 07:46

 Thread Tools

 Similar Threads Thread Thread Starter Forum Replies Last Post a1call Miscellaneous Math 179 2015-11-12 14:59 Unregistered Information & Answers 7 2010-08-12 06:25 lfm Operation Billion Digits 6 2009-01-07 01:17 Shakaru Factoring 2 2005-02-23 19:22 Unregistered Software 3 2004-03-03 19:20

All times are UTC. The time now is 15:04.

Sat Aug 15 15:04:43 UTC 2020 up 2 days, 11:40, 1 user, load averages: 1.90, 2.07, 1.92

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.