20160127, 21:12  #1 
Nov 2008
3·167 Posts 
The Factoring Report at mersenne.ca
I am nearing the end of a project to TF all exponents below 1M to at least 64 bits (is there an old version of mfaktc that do exponents < 100K anywhere?)
I pick up the ranges from this report You will see that the 0.13M range has 143 exponents left to test. If you drill down into the report... 1. click on 0.13m 2. on next page put factored through to 63 bits and get data 3. get a long list of all those candidates 4. click on output TF worktodo and enter 64 bits as the upper limit 5. Get just a SINGLE exponent back See screen caps. This report is fundamentally broken, often you will get a "complete" list, factor them out of the way then rerun the same report, you would expect no candidates right? Wrong, on many an occasion it "finds" more candidates that need checking. 
20160127, 22:05  #2  
Sep 2014
29 Posts 
Quote:


20160127, 22:28  #3  
Nov 2008
3·167 Posts 
Quote:


20160127, 22:41  #4  
Sep 2014
29 Posts 
Quote:
http://www.mersenneforum.org/showpos...&postcount=498 

20160128, 00:53  #5  
"Curtis"
Feb 2005
Riverside, CA
5^{2}·11·17 Posts 
Quote:
For every 8000 factors of 19 digits, one would be (expected to be) missed by a t25. But only ~5% of exponents have a factor of 19 digits length (or are mersennes different from the usual heuristic?), so you'd expect a missed factor something like 1 out of 160,000 tests. Note that even 25% of a t30 would halve the chances of a missed factor, and exponents at 130,000 level have a t30 complete. 

20160128, 03:10  #6  
Serpentine Vermin Jar
Jul 2014
CDA_{16} Posts 
Quote:


20160209, 23:17  #7 
Sep 2002
Oeiras, Portugal
2650_{8} Posts 
If memory serves me, 100K is the lowest we can gousing mfaktc.. Former versions wouldn´t factor exponents lower than 1M.

20160210, 06:46  #8 
Romulan Interpreter
Jun 2011
Thailand
5^{2}·7·53 Posts 
The versions of mfaktX that sieve with the GPU are like that (i.e. all since/after v0.18, for mfaktc). Older versions of mfaktc which sieve only with the CPU exist, where you can go as low as 2k for the exponent, but they are about 5 times slower (still 40 times faster than the CPU) than the last version of mfaktc, and they also keep the CPU busy (you can not run P95 in the same time, or you can, but the output is lousy). I just used one to factor all expos between 2k and 100k from 57 to 58 (sometime higher) for the "skipped bitlevels" project from Mark.
Last fiddled with by LaurV on 20160210 at 06:50 Reason: clarification added 
20160210, 08:03  #9 
Sep 2002
Oeiras, Portugal
2^{3}×181 Posts 
You´re right
Your memory is better than mine. DDR4 vs DDR2?... 
20160210, 08:07  #10 
Sep 2002
Oeiras, Portugal
2650_{8} Posts 
While we´re at it: the report isn´t updating. The latest version is from the 7th Feb.

20160225, 08:30  #11 
Sep 2002
Oeiras, Portugal
2^{3}×181 Posts 
Stuck again . Last update on the 22nd.

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