20130306, 01:46  #2223 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
10010100011001_{2} Posts 
What is your card's brand? You may want to start from their website; usually they use the clocking tools to lure you to register your product (which is not necessarily a bad idea). An older version of the tool may be on the CD/DVD that was included with the card...
EVGA Precision is here, MSI Afterburner , Gigabyte is somewhere in there... I am sure that Zotac, and others have similar web pages. 
20130306, 19:40  #2224 
"Oliver"
Mar 2005
Germany
11×101 Posts 
Wanted: help with Makefile
Hello,
since I screwed up the Windows makefile in mfaktc 0.20 (you can use for compiling mfaktc on Windows but when you change some code and recompile it won't work as expected because of some missing dependencies) I would like to merge the three Makefiles into one (if possible and feasible). For all three Makefiles (Linux, Windows and Windows 32bit) the rules are the same, what changes are the compiler and compiler options as well as the name of the object files. The second question: is it easily possible to build mfaktc in subdirectories of src/ (where to place the object files)? I'm dreaming of
Oliver 
20130306, 20:09  #2225  
If I May
"Chris Halsall"
Sep 2002
Barbados
2^{2}×3×5×163 Posts 
Quote:
The GNU build system (AKA Autotools) might help you achieve what you want. YMMV. I never compile under Windows.... 

20130307, 06:42  #2226  
Jun 2010
Pennsylvania
1110100110_{2} Posts 
Quote:
Or maybe I'll check out the included CD and actually use it for something! Rodrigo 

20130309, 14:50  #2227 
"Nancy"
Aug 2002
Alexandria
2,467 Posts 
Btw, is there a particular reason for disallowing composite exponents?

20130309, 15:41  #2228 
"Oliver"
Mar 2005
Germany
457_{16} Posts 
Hi Alex,
I didn't spent time on composite exponents, do the same rules apply for them? At least for even exponents there are factors which are +/ 3 mod 8, they are excluded in mfaktc because for prime exponents all factors are +/ 1 mod 8. Oliver 
20130309, 16:10  #2229 
"Nancy"
Aug 2002
Alexandria
2,467 Posts 
I guess we can limit ourselves to primitive divisors; divisors of algebraic factors may or may not be found but we can leave those for the user to figure out. For a primitive divisor p of 2^n1, we have np1, like for prime exponents (where every divisor > 1 is primitive).
As you note, the +1 (mod 8) thing may not work when n is even. You could still do some tricks with the quadratic character of 2, like for p==1 (mod 4) when 2n in which case 2 must be a QR for 2^n=1 to hold so we can actually restrict ourselves to p==1 (mod 8), i.e., no need to test p==5 (mod 8), but I think that can also be left alone for a start. Of course you don't need to sieve by small primes qn, since p=kn+1 is never divisible by q  if you don't skip those, the sieve init will probably try an impossible mod inverse. To get something that can be used at all, I think it's enough to allow composite expoents, allow +3 (mod 8) factors when the exponent is even, and not sieve primes that divide the exponent. 
20130310, 02:12  #2230 
"James Heinrich"
May 2004
exNorthern Ontario
2·3·571 Posts 
For what it's worth, the mfaktc performance chart now includes data (from a single benchmark, so interpret loosely) for the GTX Titan. Short story: about the same mfaktc performance as a GTX 570.
http://www.mersenne.ca/mfaktc.php 
20130310, 02:35  #2231 
Bemusing Prompter
"Danny"
Dec 2002
California
4534_{8} Posts 

20130310, 03:56  #2232 
Apr 2012
Berlin Germany
3×17 Posts 

20130310, 11:57  #2233 
"Nancy"
Aug 2002
Alexandria
2,467 Posts 
Correct, this is of no value to GIMPS as a prime search project. Some people, including me, sometimes do look for factors of large 2^n1 numbers, and it would be awesome to be able to use GPUs for the job. If factoring composite exponents is permitted, I think it should be done with minimal developer effort, even if that neglects some relatively easy optimizations that could be done, precisely because factoring such numbers is not the main purpose of mfakc.
Last fiddled with by akruppa on 20130310 at 11:58 Reason: dupe word 
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