[QUOTE=Stargate38;282954]Please fix this bug:

[CODE]>> isprime(2^127-1)
Found expression: 2^127-1
not prime
ans = 0[/CODE]
[/QUOTE]

Here (Vista) for yafu 1.28.5, 1.29.1 and 1.29.2 all say the same:
[code]
12/20/11 20:46:21 v1.28.5 @ PC, System/Build Info:
Using GMP-ECM 6.3, Powered by MPIR 2.2.0
detected Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz
detected L1 = 32768 bytes, L2 = 4194304 bytes, CL = 64 bytes
measured cpu frequency ~= 2382.630660

===============================================================
======= Welcome to YAFU (Yet Another Factoring Utility) =======
======= bbuhrow@gmail.com =======
======= Type help at any time, or quit to quit =======
===============================================================
cached 78504 primes. pmax = 1000099

>> isprime(2^127-1)

probably prime

ans = 1
[/code]

No wonder! I have 1.23. I'll download the newest version. :)

[QUOTE=Stargate38;282956]No wonder! I have 1.23. I'll download the newest version. :)[/QUOTE]

I was just going to ask what version you were using. I've also verified it works fine for the newest version (1.29.2). I'm not sure which version fixed this, but somewhere between 1.23 and 1.28.5, apparently :smile:.

[QUOTE=bsquared;282957]I'm not sure which version fixed this, but somewhere between 1.23 and 1.28.5, apparently :smile:.[/QUOTE]

I've tested all yafu-32k-Win32-versions since V1.06 and none of them says 'not prime'... all found 'probably prime' for the expression "isprime(2^127-1)".

[QUOTE=LaurV;282871]I would like to know the meaning of this, explained like for a guy who has no idea how nfs works. In which situation could appear? Is it normal, or my computer is going nuts sometimes?

[CODE]
Tue Dec 20 12:30:41 2011 multiply complete, coefficients have about 30.43 million bits
Tue Dec 20 12:30:42 2011 initial square root is modulo 548240387
Tue Dec 20 12:36:07 2011 Newton iteration failed to converge
Tue Dec 20 12:36:07 2011 algebraic square root failed
[/CODE]edit: I got it at the 6th dependency, after three times "gcd is N, no factor" and two times "gcd is 1, no factor". The 7th dependence found a factor. Never saw it till now. Still curious.[/QUOTE]
See [url="http://www.mersenneforum.org/showthread.php?p=276519&highlight=algebraic#post276519"]this thread[/url] starting around post 586 for the usual reason that this happens. I can't tell from the snippet you posted whether this was the case, but look in your log for complaints in the square root about 'no irreducible prime found' or some such.

When running yafu with "factor()", one or two ECM curves with large B1s are generally run just before NFS is started. I have found that with numbers from about C118 upwards, a curve with a B1 of 1e9 (= 1G, or "1B" as yafu puts it) can be run. Not only is this curve rather a waste of time (the time taken on this curve would be better spent running more curves at 10M), but it uses over 1.5G of memory. While this is not a problem for me, this large memory use comes without warning, and is rather unexpected as generally ECM isn't associated with using lots of memory unless you're working at very high limits, and very high limits aren't generally associated with C120s.

[QUOTE=10metreh;283143]When running yafu with "factor()", one or two ECM curves with large B1s are generally run just before NFS is started. I have found that with numbers from about C118 upwards, a curve with a B1 of 1e9 (= 1G, or "1B" as yafu puts it) can be run. Not only is this curve rather a waste of time (the time taken on this curve would be better spent running more curves at 10M), but it uses over 1.5G of memory. While this is not a problem for me, this large memory use comes without warning, and is rather unexpected as generally ECM isn't associated with using lots of memory unless you're working at very high limits, and very high limits aren't generally associated with C120s.[/QUOTE]
Agreed, it's a little much.

It reminds me; why does YAFU "skip" 3e6?

That is why you have light/normal/deep option planes, and you also can customize the ecm levels. I make quite an use of this (that is changing the planes and ecm options quite often, depending of what I am trying to factor).

[QUOTE=LaurV;283150]That is why you have light/normal/deep option planes, and you also can customize the ecm levels. I make quite an use of this (that is changing the planes and ecm options quite often, depending of what I am trying to factor).[/QUOTE]
I use it too, but 1e9 just doesn't make sense on a C118.

If you're running aliquot sequences with aliqueit -y (as I am), then you can't really customise ECM levels, as you don't want to have to "babysit" the computer and make frequent changes to the .ini file.

I've seen this behavior myself and found it annoying, but I haven't had time to do anything about it yet. I agree that it should run more curves at the previous bound before increasing the bound, up to a limit (probably the gmp-ecm "optimal" curve count for that bound).

Other planned changes:
* ECM progression to follow gmp-ecm optimal bounds when searching for factors progressively 5 digits larger (i.e., ... 1M, 3M, 11M, 43M, ...)
* plan = deep will start at the 1M ECM mark, instead of the 250k mark as it does now.