20140222, 05:53  #34 
I moo ablest echo power!
May 2013
5×347 Posts 
Running 297903607^231

20140228, 04:58  #35 
I moo ablest echo power!
May 2013
5·347 Posts 
Running 8970971^291
Having some trouble with the SNFS poly. FactorDB gives: Code:
n: 4288882318725178503864985939002570343870783101076222294692132636882637343988982346014447015553752612504342250262840696959794627098440959386503033787331436025332337203640782929696973892811770840659915530 m: 58102827030430867738060703578743851 deg: 5 skew: 0 type: snfs c5: 6476760099930193480511831281 c0: 1 rlim: 18610400 alim: 18610400 lpbr: 29 lpba: 29 mfbr: 58 mfba: 58 rlambda: 2.7 alambda: 2.7 Phi gives: Code:
n: 2580482901793422593005519906534751048235270635043096719781698476519957422481996978800942266020020022345900390998498545851996437063629641295043489044129593444543441973751813443723 # 8970971^291^29, difficulty: 208.59, skewness: 24.58, alpha: 0.00 # cost: 2.95737e+017, est. time: 140.83 GHz days (not accurate yet!) skew: 24.579 c5: 1 c0: 8970971 Y1: 1 Y0: 521238776308011431982978168044507303749321 m: 521238776308011431982978168044507303749321 type: snfs Last fiddled with by wombatman on 20140228 at 05:32 
20140228, 07:44  #36 
Jun 2003
2·2,389 Posts 
For the first one, the correct skew would be 0.00000274.
For the second one, the larger rational side coefficient implies that you should use larger rational side parameters. 
20140228, 14:12  #37 
I moo ablest echo power!
May 2013
5·347 Posts 
Much obliged for the response.
On the 1st one, with the skew set appropriately, GGNFS still gives: Code:
gnfslasieve4I14e (with asm64): L1_BITS=15, SVN $Revision$ Please set a skewness Code:
rlim: 21300000 alim: 21300000 lpbr: 29 lpba: 29 
20140228, 16:31  #38 
Sep 2009
1944_{10} Posts 
Don't bother with the poly provided by factordb. c5: 6476760099930193480511831281 is ridiculous for snfs. In general the smaller the coefficients are the better it will sieve.
phi generated a reasonable poly. How may relations per special Q does it give? A rule of thumb (originally from Fivemack) is that if you are getting less that 2 relations per Q you should go to a larger siever or raise LPB[AR] and/or MFB[AR]. There was a "ggnfs pearls of wisdom" thread to collect such advice. It's worth reading. Chris 
20140228, 16:52  #39 
I moo ablest echo power!
May 2013
5·347 Posts 
I'd have to check to get an exact number, but it was something like 1.5 relations/Q or so, which seemed really low to me. I'll try and track that wisdom threadI can definitely use any of that I can find!

20140228, 19:54  #40 
Just call me Henry
"David"
Sep 2007
Cambridge (GMT/BST)
1011001110100_{2} Posts 
The other problem with factordb polys is that it gives you the whole number to factor even if it has very small factors. msieve will find those factors and complain at you.

20140301, 16:43  #41  
Sep 2009
2^{3}·3^{5} Posts 
Quote:
Chris 

20140301, 16:53  #42  
Sep 2009
2^{3}·3^{5} Posts 
Quote:
In practice the job would still work with a yield around 1.5 per Q. It would take a little longer than with better parameters though (I've run a few like that by mistake). Chris 

20140301, 21:21  #43 
Just call me Henry
"David"
Sep 2007
Cambridge (GMT/BST)
2^{2}·3·479 Posts 

20140303, 20:57  #44  
I moo ablest echo power!
May 2013
5·347 Posts 
I upped LPBR to 30 (totally arbitrary choice), and the yield went from ~1.5 to ~2 relations/Q, so that did indeed help. It still hasn't finished gathering relations yet, but we'll see how it does with the matrix building.
Quote:


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