20120726, 03:42  #1  
Einyen
Dec 2003
Denmark
2·3·5^{2}·19 Posts 
left shifted S0 value
From the math page: http://www.mersenne.org/various/math.php
Quote:


20120726, 04:17  #2  
Basketry That Evening!
"Bunslow the Bold"
Jun 2011
40<A<43 89<O<88
3·29·83 Posts 
Quote:
11100110 230 in binary leftshifted 2 bits: 10011011 Now the third bit is the units bit, instead of the first. 228 in binary: 11100100 228 left shifted two bits: 10010011 2302=228 in twoleftshift binary: 10011011  230 twoleftshifted 00001000  2 twoleftshifted 10010011  which is 228 leftshifted two bits Last fiddled with by Dubslow on 20120726 at 04:18 Reason: s/shit/shift (unfortunately, i'm not joking) 

20120726, 04:44  #3 
Romulan Interpreter
Jun 2011
Thailand
8582_{10} Posts 
See the posts #4, #5 and #16, 17, 18 in the "don't DC them..." thread.

20120726, 05:55  #4  
"Serge"
Mar 2008
Phi(3,3^1118781+1)/3
5×1,811 Posts 
Quote:
Last fiddled with by Batalov on 20120726 at 06:02 Reason: shifted <> backshifted 

20120726, 14:35  #5  
"Forget I exist"
Jul 2009
Dumbassville
8384_{10} Posts 
Quote:
Code:
(11:32)>k=3;d=4<<k;for(x=1,4,d=d^22*(2^(2^x*k));print(d>>(2^x*k)",")) 14, 194, 37634, 1416317954, Last fiddled with by science_man_88 on 20120726 at 14:38 

20120726, 14:59  #6 
Einyen
Dec 2003
Denmark
2×3×5^{2}×19 Posts 
Ok, so this only works for left or right shifted S0 values I guess.
I was wondering if it was possible to find the penultimate LL step ( http://www.mersenneforum.org/showthread.php?t=5862 ) for the 2 other "universel" initial values s0=10 and s0=2/3 without running all the tests again. I calculated up to M33 with GMP library but the high ones would take years and years that way: penultimatellstep.txt It seems neither Prime95/mprime, Mlucas or Glucas can run LL test with s0=10 or s0=2/3. Last fiddled with by ATH on 20120726 at 15:11 
20120726, 17:28  #7 
"Serge"
Mar 2008
Phi(3,3^1118781+1)/3
5×1,811 Posts 
You can fairly easily rebuild a slightly modified Prime95 (on either win or lin) and then each test would be as long as the conventional (4<<s) tests.

20120727, 01:27  #8  
"Forget I exist"
Jul 2009
Dumbassville
20C0_{16} Posts 
Quote:


20120727, 02:16  #9  
Einyen
Dec 2003
Denmark
2×3×5^{2}×19 Posts 
Quote:
I'll try that tomorrow, but I never compiled Prime95 before. Do you know if its possible in msys+mingw for windows? 

20120727, 02:24  #10 
"Serge"
Mar 2008
Phi(3,3^1118781+1)/3
5×1,811 Posts 
On Windows, I had built with VC++; I don't remember if I tried mingw.
Once you build the vanilla binary, then you will be set for a life of experimentation. When I built it, I was getting around the builtin PRP base (was 3; now a parameter) for testing GFN'(3)s; with base 3 there were all PRPs . AFAIR, (3^{2[sup]n}[/sup]+1)/2 for n=24 and 25 were also composite, but W.K. didn't post them (I think he waits for doublechecks with other software). ...this reminds me that this could be fun to DC with geneferCUDA (slightly modified if needed: for the divisor of 2; why don't I play with that over this weekend? :knuckleflexingsmileyneeded:) Last fiddled with by Batalov on 20120727 at 02:40 
20120727, 03:57  #11 
"Richard B. Woods"
Aug 2002
Wisconsin USA
2^{2}·3·641 Posts 

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