20080217, 13:39  #1 
Dec 2007
3^{3} Posts 
How much ecm should i do???
how much ecm should i do before switching to msieve
i keep on finding that i have spent more time on ecm than msieve takes this is with numbers between 85 and 100 digits that i am having this problem i have did 35 digit ecm on a 97 digit number a couple of days ago and that turned out to be way too much could people post what rules they would use for switching to msieve i have searched the forum but found nothing thanks 
20080217, 14:04  #2  
Tribal Bullet
Oct 2004
3^{3}·131 Posts 
Quote:


20080217, 15:40  #3 
Dec 2007
3^{3} Posts 
i do the ecm on multiple pcs so that is not possible
i looked at msieves code and found Code:
static uint32 choose_max_digits(msieve_obj *obj, uint32 bits) { /* choose the amount of work to do. We want the chosen digit level to be a small fraction of what QS and NFS would need */ uint32 max_digits = 15; if (bits == 0) return 0; if (obj>flags & MSIEVE_FLAG_DEEP_ECM) { if (bits > 220) { if (bits < 280) max_digits = 20; else if (bits < 320) max_digits = 25; else if (bits < 360) max_digits = 30; else if (bits < 400) max_digits = 35; else max_digits = 40; } } return max_digits; } 
20080217, 16:07  #4  
Oct 2004
Austria
2×17×73 Posts 
Quote:
Additionally I do some p1 and p+1. 

20080217, 16:28  #5 
Dec 2007
33_{8} Posts 
it probably is just that i am used to doing a lot more

20080217, 19:41  #6 
Aug 2007
3×31 Posts 
I've heard a 2/7 rule of thumb mentioned before. For a 97digit number, that would mean stopping ECM at 25 or 30 digits if you're trying to optimize computer time.

20080217, 20:13  #7 
Dec 2007
3^{3} Posts 
before this i used 1/3 but it often stretched

20080217, 21:42  #8  
Bamboozled!
"πΊππ·π·π"
May 2003
Down not across
2^{3}×11^{3} Posts 
Quote:
Within reason, it doesn't much matter. If the factorization is nontrivial other considerations come into play, such as memory usage and communication overheads. Paul 

20080218, 10:09  #9  
Dec 2007
3^{3} Posts 
Quote:


20080218, 12:02  #10 
Bamboozled!
"πΊππ·π·π"
May 2003
Down not across
2^{3}·11^{3} Posts 

20080218, 12:25  #11 
Dec 2007
1B_{16} Posts 
thanks
this should speed me up quite a bit so i can find more 100 digit RHPs 