20140308, 21:11  #1 
Dec 2002
2^{5}×3^{3} Posts 
missed factor?
I have the following question. If I look at this page requested from the server it appears to me as if trial factoring missed the exponent that was later found by P1 factoring.
I was under the believe that that should not be possible. Any comments? 
20140308, 21:23  #2  
"Mr. Meeseeks"
Jan 2012
California, USA
100010000000_{2} Posts 
Quote:


20140308, 21:44  #3 
Dec 2002
2^{5}×3^{3} Posts 
As I understand it, trial factoring tries each possible factor up to a limit (2^amount of bits). P1 factoring tries a small amount of easy to compute factors up to a higher range. Therefore P1 should not be able to find a factor that is below the limit of the trialfactoring done. This factor is about 65 bits while trialfactoring went up to 70 bits already. Or am I missing something?

20140308, 21:56  #4 
"Kieren"
Jul 2011
In My Own Galaxy!
2×3×1,693 Posts 
[deleted by user for excessive ignorance]
Last fiddled with by kladner on 20140308 at 21:59 
20140308, 21:56  #5  
Nov 2010
Germany
255_{16} Posts 
Quote:
Maybe Never Odd Or Even can retest it with the TF program of his choice ... if it really misses the factor reliably, then a programming bug can be uncovered. I'm running it through mfakto right now ... Last fiddled with by Bdot on 20140308 at 22:00 Reason: testing this with mfakto 

20140308, 22:01  #6 
"Kieren"
Jul 2011
In My Own Galaxy!
2·3·1,693 Posts 
[Further confusion ensued..... .....will try to stop inanities cluttering the thread.]
Last fiddled with by kladner on 20140308 at 22:05 
20140308, 22:10  #7 
Nov 2010
Germany
3×199 Posts 
P1 was the original topic, but the factor has an FECM tag. But yes, a factor of a certain size should not be missed by TF when testing the range containing that size. Both P1 and ECM do not test factors by their size but use other properties of potential factors to define the search space (and therefore can find very small factors as well as very big ones).

20140308, 22:30  #8 
"Mr. Meeseeks"
Jan 2012
California, USA
2^{7}×17 Posts 

20140308, 22:42  #9 
Aug 2002
North San Diego County
2^{2}·3·67 Posts 
Adding more strangeness: James' page (also linked on the Primenet report) shows the exponent as TF'd to 64 bits.
I've got it TFing on Prime95v259; should have results in a couple of hours (IIRC, P95 tests in ascending 'bitness', so should catch the factor about 18% of the way through) or days... 
20140308, 22:52  #10  
Nov 2010
Germany
1001010101_{2} Posts 
Quote:


20140308, 23:26  #11  
Aug 2002
North San Diego County
2^{2}×3×67 Posts 
Quote:
Anyway, the factor was found, so now my concern is the reliability of NOOE's TF results (and Primenet's by association). Last fiddled with by sdbardwick on 20140308 at 23:30 

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