Software/instructions/questions

[LaurV]

I went kookoo, giving replies to myself...
Another stupid question: my srXsieve seems to cont the "seconds per factor" from the beginning of sieving, which is wrong, as the sieving was much faster in the beginning and it is much slower now. I am sure I read somewhere something related to "the last 30 factors found", however I can't remember where and about which program (it may be a different program, and/or my perception may be subjective, however the siever spits a line with a factor every ~5 seconds, and it still says that it is finding a factor per second). What I am missing?

(I think this is sr1sieve 1.4.5)

[rogue]

Originally Posted by LaurV

I went kookoo, giving replies to myself...
Another stupid question: my srXsieve seems to cont the "seconds per factor" from the beginning of sieving, which is wrong, as the sieving was much faster in the beginning and it is much slower now. I am sure I read somewhere something related to "the last 30 factors found", however I can't remember where and about which program (it may be a different program, and/or my perception may be subjective, however the siever spits a line with a factor every ~5 seconds, and it still says that it is finding a factor per second). What I am missing?

(I think this is sr1sieve 1.4.5)

I think that is sr2sieve. I don't think I modified sr1sieve to do that although I haven't looked at the code.

[LaurV]

Another stupid question: looking to this list, I see two even numbers inside. Any special reason of that? I assumed is something I don't know, and looked for those numbers on "sister projects" sites, they don't have them, and people are talking only about "50 k's", not 52.

[gd_barnes]

Originally Posted by LaurV

Another stupid question: looking to this list, I see two even numbers inside. Any special reason of that? I assumed is something I don't know, and looked for those numbers on "sister projects" sites, they don't have them, and people are talking only about "50 k's", not 52.

All bases on this project include k's that are multiples of the base (MOB). When the Riesel and Sierp base 2 conjectures were first conjectured by Mr. Riesel and Mr. Sierpinski over 60 years ago they only specified that odd k's be considered not thinking that 2k*2^n-1 could have a different prime than k*2^n-1 if the latter had a prime at n=1 (since n>=1 for all k's). If the latter does not have a prime at n=1 then the prime for k and 2k will be the same and this project does not test 2k. For example the testing for k=90646 would be the same as for k=181292 for Sierp base 2 so we do not test k=181292 but if k=90646 had a prime at n=1 than we would test k=181292. In a short discussion with Prof. Caldwell at the top-5000 site not long after this project started he concurred that multiples of the base should be included. He even asked me if our project had tested all even k's on the Sierp base 2 side for k<78557, i.e. the "1st" conjecture. (We had already and there were no even k's remaining.) At the same time that this project was started Prof. Caldwell was in the process of publishing a paper about the Sierp conjectures up to base 100 where he included them.

We believe that it is incorrect to not include multiples of the base in the conjectures since they can yield different primes than k divided by the base. (The starting bases script take it all into account.) I have chosen not to press the issue with PrimeGrid on their Riesel project and their Extended Sierp project partly because I thought it was an interesting excercise for us to do the few k's remaining and partly because I did not want to get into a debate about what the mathematicians had conjectured over 60 years ago.

Edit: If you would like to help in testing these k's along with other base 2/4 k's that we have searched to n=~2.9M base 2, I could use some help on PRPnet port 1400. See details at http://www.mersenneforum.org/showpos...81&postcount=1. It would be nice to get them pushed further ahead faster since all other base 2 k's have been searched much further.

[LaurV]

Thanks for the prompt reply. It (somehow) makes sense. I will have a look to your link right now.

[KEP]

Originally Posted by gd_barnes

Edit: If you would like to help in testing these k's along with other base 2/4 k's that we have searched to n=~2.9M base 2, I could use some help on PRPnet port 1400. See details at http://www.mersenneforum.org/showpos...81&postcount=1. It would be nice to get them pushed further ahead faster since all other base 2 k's have been searched much further.

Don't worry my friend. I have just begun a collaboration with Reb about using SRBase to complete the k=3677878 for R3 to n=2M, wich he can do in about 15 days where I would use at least 100 days. So in about 2-3 weeks, I'll move my Sandy Bridge to your aid and in about 100 days, I'll move my offline Hasswell to enhance the sieving for the current SR base 2/4 search. But even if I decide to chime in, we do still need a lotof ressources to really move somewhere, so please LaurV, if you can spare some ressources and join the effort on port 1400, we could actually start seeing some serious progress. But as stated, as soon as R3, k=3677878 is completed to n=2M, I'm moving more and more ressources to this effort running on port 1400.

[Puzzle-Peter]

I seem to remember people sieving Riesel and Sierpinski candidates for the same base in one file. How do you do that? I am looking at S/R 22 which are both at n=1M now.

[gd_barnes]

Originally Posted by Puzzle-Peter

I seem to remember people sieving Riesel and Sierpinski candidates for the same base in one file. How do you do that? I am looking at S/R 22 which are both at n=1M now.

The same way that you do k's remaining for a base on one side. Use srsieve with the -a switch and sieve to a nominal depth. Reference a k's remaining file that contains:
5128*22^n+1
3656*22^n-1

Then use sr2sieve to continue sieving the output file from the above. With one k on each side, base 22 is a great base to do this on.

[Puzzle-Peter]

Haha this is so easy I didn't even think it would work... thanks!

[Batalov]

Originally Posted by Batalov

Another interesting case. S100, k=64. Note that 100 is a square (therefore for even n, 100^n will be the 4th power). All even n's should be removed from the sieve file for k=64, but they aren't.

I attached here a more generalized version of the script that should help to remove algebraically composite candidates from CRUS-related ABCD, NPG or PFGW files. The instructions are the same as for the Riesel sieves (except, obviously, when the algebraic file is empty; then nothing needs to be done). Anyone can try this script on their own local workfiles, and Gary could run the script on all server-hosted sieve files.

Disclaimer: this script is only slightly adapted from the base=2 (which is obviously squarefree) to a general base version and as such is not taking into account special k <-> b interactions when the base is not squarefree (for these, use a sheet of paper, pencil and some thought; plus, the isPower script is somewhere here, on the forum); however, a lot of differences of squares, and sum and diffs of odd powers will be removed (e.g. try S618 or R79 or R88). And only the simplest Aurifeuillian will be removed from the Sierp series (most likely it will only happen when k=2500: 50*b^2m-+10*b^m+1 | 2500*b^4m+1; all other Aurifeuillians have a covering set of tiny factors).

[Puzzle-Peter]

What's the latest version of srsieve? I could find source code for 1.0.7 but the latest executable I found is 0.6.17. Is there a more recent executable for 64 bit linux somewhere?