.dat file message

[mnh001]

On quite a few numbers I've had YAFU quit prematurely after hours of comp time giving the message:

"A data file (.dat) exists in the current directory. It must either be removed or -R specified to resume nfs"

I've got nfs.dat, nfs.dat.p and siqs.dat in my folder.
Which one is the message talking about? And why does it need to be removed?

I've tried the -R but it just starts the factoring process back at the beginning. (I haven't let it run for
hours to get to the end again so I don't know if it actually works).

[Jayder]

Are you using the factor() command and, once it has run through the ECM phase and started the NFS phase, it displays that message? When you say, "it just starts the factoring process back at the beginning," do you mean it starts the ECM phase again? Or that it starts NFS again?

If you would like to skip the ECM phase and if you have the proper nfs.dat file, you can use the command nfs() with -R to get right to the sieving. Make sure the .dat file is for the right number, though!

[RichD]

Don't try to run multiple instances(numbers) of YAFU out of the same folder.

[mnh001]

Yes, it starts the ecm phase at the beginning. Here's an example

>> factor(12710693802015129732806670153157372359641865100878367015320157510083298481757110424410992252489345221494526239631696738601746337)

fac: factoring 12710693802015129732806670153157372359641865100878367015320157510083298481757110424410992252489345221494526239631696738601746337
fac: using pretesting plan: normal
fac: using tune info for qs/gnfs crossover
div: primes less than 10000
rho: x^2 + 3, starting 1000 iterations on C128
rho: x^2 + 2, starting 1000 iterations on C128
rho: x^2 + 2, starting 1000 iterations on C121
rho: x^2 + 1, starting 1000 iterations on C121
pm1: starting B1 = 150K, B2 = gmp-ecm default on C121
ecm: 30/30 curves on C121, B1=2K, B2=gmp-ecm default
ecm: 74/74 curves on C121, B1=11K, B2=gmp-ecm default
ecm: 214/214 curves on C121, B1=50K, B2=gmp-ecm default, ETA: 1 sec
pm1: starting B1 = 3750K, B2 = gmp-ecm default on C121
ecm: 430/430 curves on C121, B1=250K, B2=gmp-ecm default, ETA: 2 sec
pm1: starting B1 = 15M, B2 = gmp-ecm default on C121
ecm: 904/904 curves on C121, B1=1M, B2=gmp-ecm default, ETA: 10 sec
ecm: 789/789 curves on C121, B1=3M, B2=gmp-ecm default, ETA: 26 sec
A data file (.dat) exists in the current directory.  It must either be removed or -R specified to resume nfs
Total factoring time = 30575.6719 seconds

And as I mentioned, I did try factor(#) -R and it just starts over at the top re-doing the ecm. And it is the only instance of yafu running.

When you say 'Make sure the .dat file is for the right number, though!' what does that mean? The .dat file exists in the folder from the first
instance of running yafu doesn't it? There's only one nfs.dat file (well, other than the nfs.dat.p, I don't know what that one is either).
Does the .dat file get re-created every time yafu is run?

[Wick]

I usually add the -noecm switch too when I restart a job.

[chris2be8]

If you factor a number with yafu it will leave a siqs.dat file in the directory where you ran it if it used QS to factor the number (or nfs.dat and nfs.dat.p if it used NFS). You need to delete them before you start factoring another number in the same directory.

Chris

[mnh001]

Ah, ok. So get rid of all 3 files when starting a new number Got it. Thanks a bunch.

[Batalov]

When a program is confused about .dat file, always check for if .dis file has not been accidentally deleted. -- True dat! ^_^