mersenneforum.org  

Go Back   mersenneforum.org > Factoring Projects > Operazione Doppi Mersennes

Reply
 
Thread Tools
Old 2012-09-17, 23:23   #1
ATH
Einyen
 
ATH's Avatar
 
Dec 2003
Denmark

317810 Posts
Default Output bug in mmff

Ops I thought this was a typo on http://www.prothsearch.net/fermat.html but instead it seems to be a bug in mmff:

Quote:
F43 has a factor: 3916660235220715932328394753 [TF:91:92:mmff 0.23 mfaktc_barrett96_F32_63gs]
found 1 factor for k*2^45+1 in k range: 111318G to 111319G (92-bit factors) [mmff 0.23 mfaktc_barrett96_F32_63gs]

F85 has a factor: 246947940268608417020015902258307792897 [TF:127:128:mmff 0.23 mfaktc_barrett128_F64_95gs]
found 1 factor for k*2^87+1 in k range: 1595G to 1596G (128-bit factors) [mmff 0.23 mfaktc_barrett128_F64_95gs]
These 2 factors 111318179143061*245+1 and 1595863660157*287+1 are actually factors of F42 and F83 like the webpage reports not F43 and F85 as mmff reports, I checked this in c++ with GMP library as well.

Can someone correct the title of the thread?

Last fiddled with by ATH on 2012-09-17 at 23:47
ATH is offline   Reply With Quote
Old 2012-09-17, 23:52   #2
ATH
Einyen
 
ATH's Avatar
 
Dec 2003
Denmark

2×7×227 Posts
Default

Found a third one:

Quote:
F118 has a factor: 4563438810603420826872624280490561141381005313 [TF:151:152:mmff 0.23 mfaktc_barrett152_F96_127gs]
found 1 factor for k*2^120+1 in k range: 3G to 4G (152-bit factors) [mmff 0.23 mfaktc_barrett152_F96_127gs]
This factor 3433149787*2120+1 is a factor of F116, not F118.
ATH is offline   Reply With Quote
Old 2012-09-18, 01:43   #3
R. Gerbicz
 
R. Gerbicz's Avatar
 
"Robert Gerbicz"
Oct 2005
Hungary

5·13·23 Posts
Default

Quote:
Originally Posted by ATH View Post
Ops I thought this was a typo on http://www.prothsearch.net/fermat.html but instead it seems to be a bug in mmff:



These 2 factors 111318179143061*245+1 and 1595863660157*287+1 are actually factors of F42 and F83 like the webpage reports not F43 and F85 as mmff reports, I checked this in c++ with GMP library as well.

Can someone correct the title of the thread?
Yes, it is a serious bug. Have you checked that this code finds all known Fermat (prime) divisors (and the code doesn't contain them in a big table)

Last fiddled with by R. Gerbicz on 2012-09-18 at 01:46
R. Gerbicz is offline   Reply With Quote
Old 2012-09-18, 02:11   #4
ATH
Einyen
 
ATH's Avatar
 
Dec 2003
Denmark

2×7×227 Posts
Default

Quote:
Originally Posted by R. Gerbicz View Post
Yes, it is a serious bug. Have you checked that this code finds all known Fermat (prime) divisors (and the code doesn't contain them in a big table)
I checked all larger factors. The program only support n>27 and n<160 and only support k>= 224 or larger, depends a bit on the n and m I think. I checked all factors I can get the program to work with, which was 29<=n<=149 and most of the factors with k>107.

Last fiddled with by ATH on 2012-09-18 at 02:12
ATH is offline   Reply With Quote
Old 2012-09-18, 02:52   #5
LaurV
Romulan Interpreter
 
LaurV's Avatar
 
"name field"
Jun 2011
Thailand

97·101 Posts
Default

At least, is a very good sign that it finds them (for n>m-2, if we name Fm and k*2^n+1, I wondered if it will find factors if n>m-2 strictly).

(stupid question: are the third a new factor, or you tested to see if it re-finds an older factor?)

edit: @Gerbicz: I hope you wanted to be ironical. This is not a serious bug, as long as we have the right k, finding n is piece of cake... and about the program having the factors in a table, are you implying that George is a charlatan or what? I really hope you just joked!

Last fiddled with by LaurV on 2012-09-18 at 02:55
LaurV is offline   Reply With Quote
Old 2012-09-18, 03:04   #6
Prime95
P90 years forever!
 
Prime95's Avatar
 
Aug 2002
Yeehaw, FL

11101110101102 Posts
Default

This is almost certainly a bug in the aptly named "dumb num" routines in tf_validate.h
Prime95 is offline   Reply With Quote
Old 2012-09-18, 03:56   #7
Prime95
P90 years forever!
 
Prime95's Avatar
 
Aug 2002
Yeehaw, FL

2·3·19·67 Posts
Default

dumb num fixed in 0.24. If you find a new Fermat factor in 0.23 and earlier, we'll need to verify which Fermat number the factor really divides.
Prime95 is offline   Reply With Quote
Old 2012-09-18, 15:47   #8
flashjh
 
flashjh's Avatar
 
"Jerry"
Nov 2011
Vancouver, WA

1,123 Posts
Default

Quote:
Originally Posted by Prime95 View Post
dumb num fixed in 0.24. If you find a new Fermat factor in 0.23 and earlier, we'll need to verify which Fermat number the factor really divides.
Have you posted .24 source code yet?
flashjh is offline   Reply With Quote
Old 2012-09-18, 15:57   #9
Prime95
P90 years forever!
 
Prime95's Avatar
 
Aug 2002
Yeehaw, FL

2×3×19×67 Posts
Default

Quote:
Originally Posted by flashjh View Post
Have you posted .24 source code yet?
Not yet. Let's wait a few days to see if any other bugs are reported.
Prime95 is offline   Reply With Quote
Reply

Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
GFN factoring with mmff-gfn | Reservations Batalov Operazione Doppi Mersennes 41 2017-01-03 03:32
GFN factoring with mmff-gfn | Results Batalov Operazione Doppi Mersennes 126 2016-11-12 12:22
mmff checkpoints houding Factoring 1 2015-09-02 19:32
mmff parameters MattcAnderson Operazione Doppi Mersennes 2 2015-07-08 15:28
My mmff got clogged MattcAnderson Operazione Doppi Mersennes 6 2014-12-18 08:52

All times are UTC. The time now is 22:53.


Tue Oct 26 22:53:33 UTC 2021 up 95 days, 17:22, 1 user, load averages: 1.83, 1.42, 1.28

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.