20180913, 18:52  #2850  
Mar 2011
Germany
97 Posts 
Quote:
I try to give you my derivation for base 10 repunits: Similar to Mersenne factors we find for repunits that (10 is a quadratic residue mod p) Product must be +1, so either both products of (1)(1) and (+1)(+1) are possible. Filtering the possible values mod 40 gives the following allowed values: {1,3,9,13,27,31,37,39} or {±1, ±3, ±9, ±13} for 2kp+1. Thus allowed values for 2kp are: {0,2,8,12,26,30,36,38} See also: https://math.stackexchange.com/quest...rac10pright1 So if you try to adapt it to your numbers I could compile a new version. 

20180913, 19:05  #2851 
Mar 2011
Germany
97 Posts 
I know, I have it from there. And I also follow the mfaktc thread for some years. I also suffered from the Cuda 8 bug myself. It was actually me that told TheJudger that the bug in Cuda 8 was fixed after I found that my repunit adaption was working again after a cuda sdk update. What I really mean is that I would like to have a source code versioning system for mfaktc (git, svn, mercurial, ...) where one could see the progress. This allows to create different branches without affecting the original. Optimal would be hosting the source on github or gitlab. I know that there is a mfaktc repository on github, but it is not managed by TheJudger, thus I was asking. 
20180913, 19:39  #2852  
Jun 2003
3064_{8} Posts 
Quote:
From your example the Legendre (b,p)= Legendre (n*p,p)=Legendre (0,p)=0 How do we proceed from here? Thanks. 

20180914, 19:17  #2853  
Sep 2003
13×199 Posts 
Quote:
Modifying the class_needed function seems simple enough if you just want to hardcode it for some particular base, for instance 3. And the selftest stuff can be temporarily commented out. What other changes did you need to make to the rest of the source code? For instance the part where it checks against b^p − 1 rather than 2^p − 1. Are the faster kernels also applicable to Mersenne testing? Can they simply be contributed to the existing source code? 

20180914, 19:26  #2854  
Mar 2011
Germany
61_{16} Posts 
Quote:
Not sure. I am not really fluent in this kind of math (I am a theoretical physicist). My first thought was that we can use Legendre (n*p,p)=Legendre (0,p)*Legendre(n,p). Legendre (0,p) is trivially 0, so that Legendre(n,p) can be anything. But I think that we cannot use this here since we need the Legendre symbol to be equal to 1 to make some useful statements (correct me if I am wrong). 

20180914, 19:49  #2855  
Jun 2003
2^{2}×397 Posts 
Quote:
If you could compile a version that just restricts the factors to 2*k*p+1, that would be great. 

20180914, 19:59  #2856  
Mar 2011
Germany
97 Posts 
Quote:
Also a snippet from the readme:  Removed Barrett and 72 bit kernels  Removed Wagstaff related stuff  Added 64 bit kernels  Implemented repunit factorization (hardcoded)  Improved performance compared to older version (0.18repunit) about 30%  Notes  Compiling with moreclasses flag seem to be slightly faster, thus it is switched on  Not tested on Windows yet  GPU sieving utilizes 100% of the GPU, so 1 mfaktc instance is enough  GPU sieving makes the system response slow (tested on Ubuntu 14.04 64 bit with Geforce 460 GTS) Setting GPUSieveSize in mfaktc.ini to 8 or lower makes the system more responsive I did not remove the git directory, so if anybody is interested in the single commits feel free to take a closer look. I also added the linux executable. Not sure if I can quickly provide a windows variant... 

20180914, 20:07  #2857  
Mar 2011
Germany
97 Posts 
Quote:
I try to do it this weekend, but I can only provide a linux executable quickly if I succeed. Windows will take a bit longer... 

20180914, 20:14  #2858 
Jun 2003
11000110100_{2} Posts 

20180917, 14:02  #2859  
Random Account
Aug 2009
Not U. + S.A.
2,333 Posts 
Quote:
At some point, the ceiling value for exponents will need to be increased. If memory serves, the current value is 2^{32}1. A 'wishful thinking' value might be 2^{34}1 Either way, a Windows 64bit compile would be nice The current version does not work my GTX 1080 all that hard. Core temps stay in the mid 60's with factory default settings. 

20180917, 22:56  #2860  
"TF79LL86GIMPS96gpu17"
Mar 2017
US midwest
1101011010101_{2} Posts 
Quote:
Re your GTX1080, how do you know you don't simply have very good cooling? What does TechPowerUp GPUZ or CPUID HWMonitor say about gpu % load and reasons for it being less than 95100%? Are you running high enough bit depths, and/or the lessclasses version, or running on a solid state disk, so that I/O is not limiting throughput? 

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