mersenneforum.org Prime95 version 29.4
 Register FAQ Search Today's Posts Mark Forums Read

2018-12-26, 15:33   #375
GP2

Sep 2003

5×11×47 Posts

Quote:
 Originally Posted by theonetruepath So I'm hoping Microsoft will come to the party with a hotfix to enable AVX-512 in Windows 7...
I think that is a forlorn hope.

"Mainstream support" for Windows 7 ended in January 2015, and it is now on "extended support" until January 2020.

"Extended support", in Microsoft-speak, means they aren't adding any new features.

 2018-12-26, 15:49 #376 PhilF     "6800 descendent" Feb 2005 Colorado 3·227 Posts In case it hasn't already been reported, I noticed that while performing Fermat ECM work that the program will stop the worker to perform needed benchmarks, but then not perform any, then immediately restart the worker.
2018-12-27, 16:30   #377
kriesel

"TF79LL86GIMPS96gpu17"
Mar 2017
US midwest

10110101001112 Posts

Quote:
 Originally Posted by GP2 I think that is a forlorn hope. "Mainstream support" for Windows 7 ended in January 2015, and it is now on "extended support" until January 2020. "Extended support", in Microsoft-speak, means they aren't adding any new features.
When Microsoft proclaimed Windows X forever, they erred by 3.

 2018-12-27, 20:24 #378 MrRepunit     Mar 2011 Germany 3·31 Posts Hi, I just noticed that the PRP test in prime95/mprime seems to be broken since version 29.4 (at least on Linux 64 Bit). Test cases for the worktodo.txt (all should be prime): Code: PRP=1,10,19,-1,"9" PRP=1,10,23,-1,"9" PRP=1,10,317,-1,"9" PRP=1,10,1031,-1,"9" PRP=1,10,49081,-1,"9" PRP=1,10,86453,-1,"9" PRP=1,10,109297,-1,"9" PRP=1,10,270343,-1,"9" latest 29.3 works fine, 29.4b8 and 29.5b5 give composites as results with the following example output: Code: 10^270343-1/9 is not prime. Type-5 RES64: 8E38E38E38E38E39 My guess is an off-by-one error in the iteration count. Last fiddled with by MrRepunit on 2018-12-27 at 20:31 Reason: not sure which exact build version 29.3 is
2018-12-27, 23:54   #379
GP2

Sep 2003

5×11×47 Posts

Quote:
 Originally Posted by MrRepunit Hi, I just noticed that the PRP test in prime95/mprime seems to be broken since version 29.4 (at least on Linux 64 Bit).
Type 5 residues don't work in 29.4, except for Wagstaff (and for Mersenne, type 1 and type 5 are the same thing). I reported the problem a while ago.

Type 1 residues do work, and since there is no Gerbicz error checking for repunits other than Mersenne (b=2) and Wagstaff (b=−2), there is no advantage to using type 5 for any bases other than Mersenne and Wagstaff.

You can get type 1 residues with PRP base = 3 by specifying, for example:

Code:
PRP=1,10,19,-1,"9",99,0,3,1
For type 5 you can change the ,99,0,3,1 to ,99,0,3,5 or just omit it entirely.

The drawback is that the numerical value of a non-zero type-1 residue will be entirely different from the non-zero type-5 residue for the same composite Mersenne number. So you can't mix and match results for the two residue types.

In 29.4, for the exponent 19 I got the type 5 residue 0x7B5BAD595E238E39, which is 8888888888888888889 in decimal.

By reverse engineering, I figured out what mprime 29.4 is actually calculating when it calculates residues:

Code:
zero = mpz(0)
one = mpz(1)
minus_two = mpz(-2)

b = mpz(args.repunit)              # 10
a = mpz(args.prp_base)             # 3

t = args.bit_length                # 64
pow2_t = mpz(1<<t)

if b > zero:
mp_numer = b**p - one
mp_denom = b - one
mp_ratio = mp_numer // mp_denom
if args.residue_type == 1:
res = pow(a, mp_ratio - one, mp_ratio) % pow2_t
elif args.residue_type == 5:
res = pow(a, mp_ratio - one, mp_numer) % pow2_t
else:
mp_numer = (-b)**p + one
mp_denom =  -b + one
mp_ratio = mp_numer // mp_denom
if args.residue_type == 1:
res = pow(a, mp_ratio - one, mp_ratio) % pow2_t
elif args.residue_type == 5 and b != minus_two:
res = pow(a, mp_ratio - one, mp_numer) % pow2_t
elif args.residue_type == 5 and b == minus_two:
res = pow(a, mp_numer - one, mp_numer) % pow2_t

Last fiddled with by GP2 on 2018-12-27 at 23:58

 2018-12-28, 00:51 #380 PhilF     "6800 descendent" Feb 2005 Colorado 3·227 Posts Hmmm. While doing a 50M double check, I just got a Jacobi error. After it was finished checking through backup files, it reported the chances of a good test as "fair". The test is 50% done. After I investigate and decide the hardware is fixed, should I start the test over and lose 5 days for sure, or should I let it finish and lose 10 days, but only if the test turns out to be bad? Last fiddled with by PhilF on 2018-12-28 at 00:52
2018-12-28, 01:34   #381
Mark Rose

"/X\(‘-‘)/X\"
Jan 2013

37×79 Posts

Quote:
 Originally Posted by PhilF Hmmm. While doing a 50M double check, I just got a Jacobi error. After it was finished checking through backup files, it reported the chances of a good test as "fair". The test is 50% done. After I investigate and decide the hardware is fixed, should I start the test over and lose 5 days for sure, or should I let it finish and lose 10 days, but only if the test turns out to be bad?
With one error, I'd let it run. If you see multiple errors in a run, I'd switch the machine to PRP work.

 2018-12-28, 03:14 #382 Uncwilly 6809 > 6502     """"""""""""""""""" Aug 2003 101×103 Posts 271D16 Posts That is what DC's are for, checking on machines.
2018-12-28, 03:31   #383
Prime95
P90 years forever!

Aug 2002
Yeehaw, FL

7×1,091 Posts

Quote:
 Originally Posted by Mark Rose I'd switch the machine to PRP work.
Switch the machine to PRP testing for all future tests.

2018-12-28, 05:40   #384
LaurV
Romulan Interpreter

"name field"
Jun 2011
Thailand

263B16 Posts

Quote:
 Originally Posted by PhilF The test is 50% done.<...> should I start the test over and lose 5 days for sure, or should I let it finish and lose 10 days, but only if the test turns out to be bad?
The "confidence" of the check is 50%, so your chances are equal, either way. You have 100% lose 5 days or 50% lose 10 days, hehe.You don't know what happens if you start again, it may repeat some error (the chances are not 100% to be successful, you may lose the 5 days, plus some other in the future, but of course, that was only a joke, because it sounded funny).

I would let it finish. And after, switch to PRP testing (where the error check is more robust), at least for next few exponents, to be sure the hardware is really fixed.

 2018-12-28, 23:47 #385 GP2     Sep 2003 A1916 Posts I can't remember if I asked this before, but... We can't do PRP base 2 for Mersenne or Wagstaff testing, so by default we choose PRP base 3. However, for other choices of b in k*b^n+c, we could use PRP base 2. For instance, for repunits using b=10, we could use either PRP base 2 or base 3 (or others). Would there be any speed advantage to using PRP base 2 over base 3?

 Similar Threads Thread Thread Starter Forum Replies Last Post Prime95 Software 148 2012-03-18 19:24 Prime95 Software 76 2010-12-11 00:11 Prime95 PrimeNet 369 2008-02-26 05:21 Prime95 PrimeNet 143 2007-09-24 21:01 pacionet Software 74 2006-12-07 20:30

All times are UTC. The time now is 18:02.

Sat Oct 23 18:02:07 UTC 2021 up 92 days, 12:31, 0 users, load averages: 1.16, 1.20, 1.17