20170306, 09:35  #1 
Banned
"Luigi"
Aug 2002
Team Italia
4844_{10} Posts 
What is the next B1?
I am focusing on ECM on Fermat numbers with mprime.
My question is: what is the next B1 range for F12, after 800,000,000? I have heard people doing B1 = 2,900,000,000, is it correct? 
20170306, 12:33  #2  
Jun 2012
2^{2}·5^{3}·7 Posts 
Quote:


20170306, 14:42  #3  
Banned
"Luigi"
Aug 2002
Team Italia
4844_{10} Posts 
Quote:
1  I am using mprime, not GMPECM: mprime has different B2 parametrization. 2  The page at https://www.mersenne.org/report_ecm/ based on mprime work over Fermat ecm shows B1 = 800,000,000 instead of 850,000,000. Luigi 

20170306, 15:56  #4 
Jun 2012
2^{2}·5^{3}·7 Posts 
Sorry I missed the fact you're using mprime. Don't have optimal parameters for it, though I suspect they are close to gmpecm in magnitude. Good luck!

20170306, 16:21  #5 
Just call me Henry
"David"
Sep 2007
Liverpool (GMT/BST)
5984_{10} Posts 
If you are talking about optimal you would change the bounds after every curve.
Here is some reading http://www.mersenneforum.org/showthread.php?t=21420 