mersenne.ca

[James Heinrich]

Originally Posted by Zhangrc

Suggestion: Show "MISSED FACTOR!" in P-1 results too

Thanks for the suggestion, implemented.

[kruoli]

Originally Posted by VBCurtis

Can you give us an example of an exponent where you think the original P-1 work missed the factor, and the bounds for the previous P-1?

Concrete example, found with James's tool: M13258937_.ca.

[axn]

Originally Posted by VBCurtis

Can you give us an example of an exponent where you think the original P-1 work missed the factor, and the bounds for the previous P-1? It's more likely you found factors with bigger bounds than all 4 of your finds would have been found by the old bounds.

There has been a shockingly large number of P-1 misses that I've found as part of <20M project

27.0 - https://www.mersenne.ca/p1missed.php...0&max=27100000 - anything 75+ bits is found by me where the previous P-1 should've found
19.5 - https://www.mersenne.ca/p1missed.php...0&max=19600000 - anything 73+ bit is found by me via P-1 or by TF (not me) recently. I am not yet done with 19.5, so more could get uncovered.

The original P-1 were all done way back around 2003 or so. Nonetheless, it is disturbingly large amount of bad P-1.

[Luminescence]

Originally Posted by James Heinrich

Thanks for the suggestion, implemented.

Maybe a bug? 10480469 shows a missed factor, but this P-1 test has probably been run with the known factor since it was done after SRBase found it

[masser]

Missed P-1 factors discussed frequently here.

TL;DR: Early results (say pre-2003) aren't necessarily reliable.

[VBCurtis]

Originally Posted by James Heinrich

https://www.mersenne.ca/p1missed.php

Wow, that's a lot of missed factors!

Thanks for the corrections, and sorry to suggest Zhang was mistaken.

[axn]

Originally Posted by axn

I am not yet done with 19.5, so more could get uncovered.

Hot off the press - 19552763

[nordi]

The "Missed Factor" feature seems to still be a bit buggy:

https://www.mersenne.ca/exponent/12133333
Those newly discovered factores require larger B2 values than 400k, so they were not missed by the P-1 run with B1=B2=400,000.

https://www.mersenne.ca/exponent/726064763
The TF/P-1 that got flagged was done after the respective factors were discovered.

[James Heinrich]

Originally Posted by nordi

The TF/P-1 that got flagged was done after the respective factors were discovered.

I have changed the code to only flag as "MISSED FACTOR" where the P-1 run was done before discovery date of the factor in question. Ctrl-F5 may be needed to refresh pages you've already looked at recently.

Originally Posted by nordi

Those newly discovered factores require larger B2 values than 400k, so they were not missed by the P-1 run with B1=B2=400,000.

If you mouse-over any "MISSED FACTOR" text you'll see the first (smallest) factor the code has noticed should have been found.

[nordi]

Originally Posted by James Heinrich

I have changed the code to only flag as "MISSED FACTOR" where the P-1 run was done before discovery date of the factor in question.

Thanks, looks much better now! 726064763 still has false positives for TF, though.

[James Heinrich]

Originally Posted by nordi

Thanks, looks much better now! 726064763 still has false positives for TF, though.

Not false positives, the result clearly says no factor from 2^82 to 2^83 and there is a known 82.568-bit factor. How else am I supposed to interpret this?
If the user did indeed factor from 82-83 complete and did not stop after finding the factor, the it should be reported as a completed TF-F run, with factor, not as TF-NF.