20130126, 16:13  #34  
"Mike"
Aug 2002
2^{2}·3·643 Posts 
Quote:


20130126, 16:41  #35 
Bemusing Prompter
"Danny"
Dec 2002
California
2,311 Posts 
The chances of a false positive this time is almost nil. We all know Curtis Cooper is never wrong.

20130126, 18:29  #36 
"Åke Tilander"
Apr 2011
Sandviken, Sweden
2×283 Posts 
Thanks Xyzzy I am happy for that and looking forward to the publication of it as soon as the new Mersenne prime has been thoroughly confirmed and publically anounced.

20130126, 18:49  #37  
Bemusing Prompter
"Danny"
Dec 2002
California
100100000111_{2} Posts 
Here are the most recent results from Curtis Cooper that were submitted before the purported prime was noticed:
Code:
curtisc wd10203l 58917769 C Jan 25 2013 11:38PM 71.1 130.8875 44DCF2B8559C18__ curtisc jckl4570 56183053 C Jan 25 2013 11:03PM 44.6 119.0769 4A31AD9F0DDFF5__ curtisc jckl4591 59546191 C Jan 25 2013 11:00PM 48.4 132.2835 CD350961C451D6__ curtisc wcm22003l 59061763 C Jan 25 2013 10:45PM 65.1 131.2073 2FAD4B2069D2CF__ curtisc wde261011l 49714487 C Jan 25 2013 10:20PM 33.8 91.0742 321A0CF054A800__ curtisc wde310717l 50137189 C Jan 25 2013 10:12PM 41.8 91.8485 3AD1598A834E2C__ curtisc wde261034l 59560279 C Jan 25 2013 8:34PM 48.2 132.3148 1C873BE2C88102__ curtisc jckl4576 52055909 C Jan 25 2013 8:02PM 38.8 99.7286 10E8BB5D808F74__ curtisc jcklccd62l 56193461 C Jan 25 2013 7:40PM 42.3 119.0989 6BB4AF9EFB70A6__ curtisc wcm20107l 60563023 C Jan 25 2013 6:55PM 28.2 134.5424 3E018F00191A30__ curtisc lov113022l 59135017 C Jan 25 2013 6:11PM 53.9 131.3701 8C99457344B8E7__ curtisc csc14104s 58443731 C Jan 25 2013 6:08PM 84.1 123.8682 E7C12B5A206607__ curtisc grn01617l 57161879 C Jan 25 2013 5:53PM 48.4 121.1514 50639413919D04__ Quote:
Let the sleuthing begin! Last fiddled with by ixfd64 on 20130126 at 19:19 

20130126, 19:14  #38  
∂^{2}ω=0
Sep 2002
República de California
23104_{8} Posts 
Quote:
Sergey continued to play with alternate (larger than default) FFT lengths and various thread counts this morning, and just a little while ago informed me he gets 0.011 sec/iter running @3328K (= 13*2^18 doubles) with 26 threads on a 32core box. That is roughly what should be achievable using a mere 4 cores on Sandy/Ivy Bridge once the AVX code comes online, but for now we gotta run with what we got. :) Last fiddled with by ewmayer on 20130126 at 21:33 Reason: Wrap top sekrit stuff in der [spoiler] tags, ja 

20130126, 19:31  #39 
Sep 2002
Database er0rr
3,449 Posts 
So it is about a week for a CPU based confirmation. How long for the GPU one?

20130126, 20:07  #40  
Oct 2010
191 Posts 
Quote:
Code:
else if( p >= 58050001 && p <= 62850000) /* 3328K */ 

20130126, 20:21  #41  
Einyen
Dec 2003
Denmark
2,969 Posts 
Quote:
Quote:
Is that the crossover for Mlucas? That means the exponent is < 58050000. Last fiddled with by ATH on 20130126 at 20:25 

20130126, 20:40  #42 
Oct 2010
191 Posts 
That was taken from the (online) sources of v2.8x.
This is from the sources of v3.0x (comment at the end of get_fft_radices.c) (FFT size / maxP value) Code:
2816 K 53792328 3072 K 58569855 3328 K 63338470 3584 K 68098867 Last fiddled with by Ralf Recker on 20130126 at 20:43 
20130126, 20:42  #43  
∂^{2}ω=0
Sep 2002
República de California
2^{2}×31×79 Posts 
Quote:
Code:
/* For a given FFT length, estimate maximum exponent that can be tested. This implements formula (8) in the F24 paper (Math Comp. 72 (243), pp.15551572, December 2002) in order to estimate the maximum average wordsize for a given FFT length. For roughly IEEE64compliant arithmetic, an asymptotic constant of 0.6 (log2(C) in the the paper, which recommends something around unity) seems to fit the observed data best. */ uint32 given_N_get_maxP(uint32 N) { const double Bmant = 53; const double AsympConst = 0.6; const double ln2inv = 1.0/log(2.0); double ln_N, lnln_N, l2_N, lnl2_N, l2l2_N, lnlnln_N, l2lnln_N; double Wbits, maxExp2; ln_N = log(1.0*N); lnln_N = log(ln_N); l2_N = ln2inv*ln_N; lnl2_N = log(l2_N); l2l2_N = ln2inv*lnl2_N; lnlnln_N = log(lnln_N); l2lnln_N = ln2inv*lnlnln_N; Wbits = 0.5*( Bmant  AsympConst  0.5*(l2_N + l2l2_N)  1.5*(l2lnln_N) ); maxExp2 = Wbits*N; /* 3/10/05: Future versions will need to loosen this p < 2^32 restriction: */ ASSERT(HERE, maxExp2 <= 1.0*0xffffffff,"given_N_get_maxP: maxExp2 <= 1.0*0xffffffff"); /* fprintf(stderr,"N = %8u K maxP = %10u\n", N>>10, (uint32)maxExp2); */ return (uint32)maxExp2; } /* Here a simple PARI 'script' to return maxExp for any desired Bmant = 53.; AsympConst = 0.6; ln2inv = 1.0/log(2.0); N = [enter FFT length in #doubles] ln_N = log(1.0*N); lnln_N = log(ln_N); l2_N = ln2inv*ln_N; lnl2_N = log(l2_N); l2l2_N = ln2inv*lnl2_N; lnlnln_N = log(lnln_N); l2lnln_N = ln2inv*lnlnln_N; Wbits = 0.5*( Bmant  AsympConst  0.5*(l2_N + l2l2_N)  1.5*(l2lnln_N) ) maxExp2 = Wbits*N */ On a separate note: Bad, wicked, naughty, evil 

20130126, 20:47  #44 
"Brian"
Jul 2007
The Netherlands
6300_{8} Posts 
I've only just spotted this thread despite looking at the forum several times since it started. The title successfully put me off: I thought it was the crank thread in Misc. Math so I ignored it. Bet I'm not the only one who missed it for that reason.
Exciting stuff! This is what we're here for! 
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