20071204, 22:02  #1 
"Jason Goatcher"
Mar 2005
110110110001_{2} Posts 
Newpgen worthwhile for n*2^n+/1 numbers?
PrimeGrid has finished their sieving and they only got up to about 2^33(a little under 8.6G).
I'm wondering if it would be a good idea to throw newpgen at these numbers? And, if, so, how high should I go? Also, I'm running Linux, and I've heard that newgen can be run commandline under Linux, is that true? I tried a number and it was banging along at about 10G every 1:30(m:s). 
20071205, 00:59  #2  
"Mark"
Apr 2003
Between here and the
13×463 Posts 
Quote:
BTW, I also gave Geoff the code so that gcwsieve would not need to rely on MultiSieve for the initial sieving, but AFAIK, he has not implemented it. 

20071205, 01:02  #3 
Jun 2003
7·683 Posts 
NewPGen cannot handle these series. It can do "fixedn variablek" or fixedk variablen" sieves, but CullenWoodalls are "variablen variablek" (ok, well n /is/ the k), and so NewPGen can't.
I am aware of only two publicly available programs  rogue's multisieve and geof's gwcsieve  that can handle these series. And the latter is being used by PrimeGrid. EDIT: Beaten to the post by rogue :) Last fiddled with by axn on 20071205 at 01:03 
20071205, 03:01  #4 
"Jason Goatcher"
Mar 2005
5·701 Posts 
I don't think you two considered my post for much longer than it took to skim it. 10G in a minute and a half is nothing to sneeze at, and you'll note that I was informed enough about gcwsieve to know that it had gotten to about 2^33 using PrimeGrid software(I suppose I didn't state that last part straight out, but I think it would be kind of obvious to someone who was knowledgeable of the sieving scene in general, given a little thought)
So, I'll restate my question, which I don't consider answered. Does anyone think it would be worthwhile to take the various numbers individually higher using NewPGen, like say, a bitlevel or two. Or, maybe not even a bit level. 
20071205, 03:23  #5  
"Mark"
Apr 2003
Between here and the
13×463 Posts 
Quote:
BTW, I believe that gcwsieve will be faster than NewPGen for a single n, but only testing that hypothesis will prove it to be correct. 

20071205, 03:38  #6 
"Jason Goatcher"
Mar 2005
5·701 Posts 
Ok, thanks for the answer, and sorry for my stiff response. 10G in a minute thirty seemed fast to me and I didn't think that that had been noticed.

20071205, 03:52  #7  
Jun 2003
7·683 Posts 
Quote:
Quote:
90 seconds to 2^34  2.9% chance of factor. 270 seconds to 2^35  5.7% chance of factor. 630 seconds to 2^36  8.3% chance of factor 1350 seconds to 2^37  10.8% chance of factor Breakeven points (i.e., how long must an LLR test take for these to be worthwhile). To 2^34: 90 + (12.9%)*t = t ==> t = 90/.029 = 3100 sec. To 2^35: t = 270/.057 = 4700 sec To 2^36: t = 7500 sec To 2^37: t = 12500 sec. So, depending on the t value (LLR test time), you can decide how far you can sieve. NOTE that these are /breakeven/ points  the optimal sieving point will be somewhat lesser (or alternately, the LLR test time should be greater than what is indicated) Last fiddled with by axn on 20071205 at 04:02 Reason: added clarification 

20071205, 04:17  #8  
Mar 2003
New Zealand
485_{16} Posts 
Quote:
Quote:
My 2.88GHz Celeron is sieving about 58,000 numbers for PrimeGrid at the rate of about 46,000 p/sec. That is equivilent to 240G for one number in 90 sec. Unless your machine is 24 times slower than mine, you are wasting your time. 

20071205, 04:29  #9 
"Jason Goatcher"
Mar 2005
5·701 Posts 
Thanks for the response, and sorry for the harsh words. I'm positive I've rushed to respond to something I didn't read adequately in the past, I just can't think of anything in particular. In the meantime, I need to Google 'mea culpa' to find out precisely what it means, since I'm only familiar with the context it's used in and not the precise meaning.

20071205, 04:44  #10  
"Jason Goatcher"
Mar 2005
5×701 Posts 
Quote:
Last fiddled with by jasong on 20071205 at 04:47 

20071205, 05:14  #11  
Jun 2003
7×683 Posts 
Quote:
Ah, here is the thread in question  looks like the sieve reservation has reached 2^43. [PS: I must be having a really off day  getting a C/W sieve to 2^33 is like a week's job on a single PC] 

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