20150206, 00:00  #1 
Apr 2011
2^{6} Posts 
.dat file message
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). 
20150206, 02:33  #2 
Dec 2012
2·139 Posts 
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! 
20150206, 03:36  #3 
Sep 2008
Kansas
6376_{8} Posts 
Don't try to run multiple instances(numbers) of YAFU out of the same folder.

20150206, 09:01  #4 
Apr 2011
2^{6} Posts 
Yes, it starts the ecm phase at the beginning. Here's an example
Code:
>> 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 = gmpecm default on C121 ecm: 30/30 curves on C121, B1=2K, B2=gmpecm default ecm: 74/74 curves on C121, B1=11K, B2=gmpecm default ecm: 214/214 curves on C121, B1=50K, B2=gmpecm default, ETA: 1 sec pm1: starting B1 = 3750K, B2 = gmpecm default on C121 ecm: 430/430 curves on C121, B1=250K, B2=gmpecm default, ETA: 2 sec pm1: starting B1 = 15M, B2 = gmpecm default on C121 ecm: 904/904 curves on C121, B1=1M, B2=gmpecm default, ETA: 10 sec ecm: 789/789 curves on C121, B1=3M, B2=gmpecm 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 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 recreated every time yafu is run? Last fiddled with by mnh001 on 20150206 at 09:37 
20150206, 12:14  #5 
Nov 2012
2^{3}×3^{2} Posts 
I usually add the noecm switch too when I restart a job.

20150206, 17:01  #6 
Sep 2009
2·1,021 Posts 
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 
20150206, 23:22  #7 
Apr 2011
40_{16} Posts 
Ah, ok. So get rid of all 3 files when starting a new number Got it. Thanks a bunch.

20150207, 07:37  #8 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
2·3·1,571 Posts 
When a program is confused about .dat file, always check for if .dis file has not been accidentally deleted.  True dat! ^_^

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