20120413, 13:16  #1 
2·3·29·41 Posts 
TF times
Hi,
Why is it that TF M805085069 from 65 to 66 bits takes 4 minutes but TF M101108803 from 65 to 66 bits takes half an hour on the same CPU? 
20120413, 14:06  #2 
Aug 2009
Ontario, Canada
203_{8} Posts 
As a number gets larger there are fewer possible factors to test in a range.
A potential factor has the form 2*p*k+1. This means when comparing p=805085069 and p=101108803 you would expect that there are approx 7.9 times (805085069/101108803) more factors to test in the 100M number vs the 800M number. This means the time would be approx 7.9 times longer. 4 minutes * 7.9 is approx 31 minutes Grant. 
20120413, 14:06  #3 
Oct 2011
7·97 Posts 
It sounds like there is a process running in the background causing a slowdown during your testing, as the time to run a 100M exp to a given bit level will always take less time than 80M exponent.

20120413, 14:13  #4 
5×1,597 Posts 
Thanks a lot gjmccrac, this explains it.

20120413, 14:53  #5 
1976 Toyota Corona years forever!
"Wayne"
Nov 2006
Saskatchewan, Canada
2·3·773 Posts 

20120413, 19:23  #6  
"Forget I exist"
Jul 2009
Dumbassville
2^{6}×131 Posts 
Quote:


20120413, 19:40  #7 
Oct 2011
7×97 Posts 

20120414, 11:45  #8 
May 2011
Orange Park, FL
2·443 Posts 
It's hard to read these; it would help to put commas in.
M805,085,069 
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