Software/instructions/questions

[rogue]

Originally Posted by KEP

Is srsieve version 1.0.5 working correct with removing algebraric factors?

I'm asking because I'm currently in the process of sieving 4 k's to p=1P, but I'll have to start from scratch if too many n's has been removed. So can someone elaborate and tell me, weather or not this version of srsieve is working correct or not?

Nobody has reported any issues. It would be easy enough to modify the code to print all k/b/n removed due to algebraic factorizations so that you could verify.

[KEP]

Originally Posted by rogue

Nobody has reported any issues. It would be easy enough to modify the code to print all k/b/n removed due to algebraic factorizations so that you could verify.

Well I'm good as it is now, it tells me an amount of n's removed by algebraric factorization. In addition mathew steine conquered that the amount of candidates seemed to be ok, since the amount of candidates remaining was about 700 candidates lower after resieving with the never version of srsieve. So now I've two persons that has told me, that to the best of their knowledge there is no apparent issues with the software and that is enough to reassure me that everything is all-right :)

Thanks for your reply.

KEP

[TheCount]

I've started testing 20*620^n-1 from 100k to n=200k. I am currently at about 2.7% of the range using one CPU core and PFGW. At this rate it will take 200+ days to finish! I have a 6 core CPU. Reading this thread I can either setup a PRPnet server on my PC, use a private port on the NPLB server or manually split the sieving file into 6 parts and feed each core. For just starting out I want to try the later. Just splitting the sieve file into 6 equal parts by increasing n is dumb because if the prime is 10% through the range I won't know until each core has done 10% of the work (ignoring increasing WU size). Plus the cores doing the smaller n will finish first etc. A better way is to take each 6th line of the sieve file and put it into a separate file, one file for each core. Does someone have a Windows DOS batch file that can do this?

I hope reporting 6 results files crunched this way won't be a problem?

[LaurV]

If you used NewPgen to make the file, it can automatically split it in 6, to be checked for primality in 6 different computers (or same computer, 6 cores). It can automatically generate six pfgw-type files. I just started sieving "k*b^n-1 with k fixed", from n=100000 to 200000 and after 5 minutes of sieving there are about 5800 candidates remaining. Most probably the number is much lower if you sieve higher. So, I still don't get it why it takes so long to test them for primality in your machine. How long does pfgw takes for one test?

[TheCount]

I have ~3800 candidates left after sieved to P=5T. At 60% of range takes 80 minutes per test on my AMD X6 1100T clocked at 3.5GHz.
80 mins x 3800 candidates = 211 days. This is for a 1k'er.
NewPgen isn't in the CRUS Pack. I got the sieve file off the CRUS web page: http://www.noprimeleftbehind.net/cru...e-reserves.htm
Sure I can sieve 6 different n ranges and crunch that separately on each core, but its not very efficient as I argued in my post.
Where can I find NewPgen?

[LaurV]

Then you have a well-sieved file, won't need another, and won't need NewPgen (by the way).

What you need is a card-dealer, like this. Paste your text inside, select 6 stacks, there you go, paste them back in 6 files. If your file has some header, don't forget to put the header in all files.

(for a small test, type numbers from 1 to 10, each on a line, select 3 stacks, deal, etc)

(edit: related to NewPgen, which I forgot it running since the time of my first post in this thread (what an idiot!), it reached 5G2, it still has 4930 candidates, and it is still eliminating one candidate every 34 seconds. I have no idea how tough is getting further, I will stop it, generally the time increases exponentially when the candidates base is reduced, but if your computer has a fast memory, you may get to eliminate one candidate faster than the 80 minutes, if you continue sieving from the file you have. This would worth a test, in my opinion).

[gd_barnes]

LaurV, please do not recommend to a new searcher on this project to sieve with NewPGen. It's the slowest possible way to sieve on this project. We use srsieve/sr2sieve -or- for 1k, sr1sieve...far faster. Thank you.

The card-dealer link is very good. I always used Excel to split it up in such a manner. TheCount, I would recommend using LaurV's link to split your file up into 6 separate parts where each one of them will take about the same amount of time to test and little CPU time will be wasted if you find a prime. That way, you can be done in ~35 days if you have your computer running 24x7 and don't find a prime.

One thing that surprises most new people here is the amount of time that it takes to test ranges. With the project being nearly 6 years old, all of the "low lying fruit" has already been tested.

[LaurV]

Whoops....
(I hope I will get some mitigation on the fact that when I replied, I didn't know where the file comes from).

The link to the splitter is not my merit either, I have it from James' site (somewhere in the right, under "work balancer" or so). I use a small perl script (one liner) to do this, but I didn't want to bother the OP about perl.

@OP: please forget what I said about NewPgen, and sorry for inducing you in a wrong direction. For me NewPgen is still the fastest way to sieve

[gd_barnes]

Originally Posted by TheCount

I hope reporting 6 results files crunched this way won't be a problem?

No problem. One thing that I eventually suggest is to take the 6 files and sort them back by n-value by parsing out the n before sending one big sorted file to me.

[rogue]

Originally Posted by TheCount

I've started testing 20*620^n-1 from 100k to n=200k. I am currently at about 2.7% of the range using one CPU core and PFGW. At this rate it will take 200+ days to finish! I have a 6 core CPU. Reading this thread I can either setup a PRPnet server on my PC, use a private port on the NPLB server or manually split the sieving file into 6 parts and feed each core. For just starting out I want to try the later. Just splitting the sieve file into 6 equal parts by increasing n is dumb because if the prime is 10% through the range I won't know until each core has done 10% of the work (ignoring increasing WU size). Plus the cores doing the smaller n will finish first etc. A better way is to take each 6th line of the sieve file and put it into a separate file, one file for each core. Does someone have a Windows DOS batch file that can do this?

For you I would suggest using PRPNet and this reason. If one core finds a prime the others will be doing PRP tests for no reasons. With PRPNet you can load up a second conjecture while working on the first one without having to touch clients.

[kar_bon]

Originally Posted by TheCount

A better way is to take each 6th line of the sieve file and put it into a separate file, one file for each core. Does someone have a Windows DOS batch file that can do this?

I've done this for a 500 k-range with ~3M candidates allover.

You can do this:
- say your file with all candidates named "all.txt" (in newpgen-format: first line header, other lines k-n-pairs)
- get "gawk.exe" (you can find it here)
- create a file called "do.awk" with following content:

BEGIN{ getline line; i=1}
{ if (head[i] == 0)
  { print line >>"all_"i".txt"
    head[i]=1
  }
 print $0 >>"all_"i".txt"
  i++
  if (i==7) i=1
}

- calling the command "gawk -f do.awk all.txt" will create 6 files (all_1.txt, all_2.txt,...) with all candidates distributed (every 6.th pair is in the same file) and the header in the first line.