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Old 2009-08-08, 05:13   #1
yoyo
 
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Oct 2006
Berlin, Germany

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Default strange GMP-ECM result

One of my users produced this result:
Quote:
GMP-ECM 6.2.3 [powered by GMP 4.2.1_MPIR_1.1.1] [ECM]
Input number is 68041741615741623915207425538974223056748602099726427231616331003526999848300888579983762851853034810843224623915901131434344795520782871939702440085310267655637388231851100018258972683441081321013639182209704229603692480356999639503223453710288824380537222381381849062334376700891694074667249672626291134132048842294147515487592992255235218463758508655668054371763140288526076065155338723497990305519992546468415874510212192311593271815094279136472506674314781234445069160720815522864774614508253731389365109822581064707596101854051293474507018777103872811353020669831583802817979796399242735752201655664299872455218130581340058214411457698515851354238904187139422050546188547 (677 digits)
[Thu Aug 06 11:37:01 2009]
Using special division for factor of 2^2281+1
Using B1=43000000, B2=198654756318, polynomial Dickson(12), sigma=3056052712
dF=92160, k=2, d=1021020, d2=19, i0=24
Expected number of curves to find a factor of n digits:
20 25 30 35 40 45 50 55 60 65
2 5 15 56 253 1323 7837 51385 373591 2960912
Step 1 took 3508188ms
********** Factor found in step 1: 5
Found probable prime factor of 1 digits: 5
Composite cofactor 68041741615741623915207425538974223056748602099726427231616331003526999848300888579983762851853034810843224623915901131434344795520782871939702440085310267655637388231851100018258972683441081321013639182209704229603692480356999639503223453710288824380537222381381849062334376700891694074667249672626291134132048842294147515487592992255235218463758508655668054371763140288526076065155338723497990305519992546468415874510212192311593271815094279136472506674314781234445069160720815522864774614508253731389365109822581064707596101854051293474507018777103872811353020669831583802817979796399242735752201655664299872455218130581340058214411457698515851354238904187139422050546188547 has 677 digits
It was on this host http://www.rechenkraft.net/yoyo/show...p?hostid=31425

yoyo
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Old 2009-08-08, 07:09   #2
10metreh
 
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Nov 2008

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Quote:
Originally Posted by yoyo View Post
One of my users produced this result:

It was on this host http://www.rechenkraft.net/yoyo/show...p?hostid=31425

yoyo
This might be a hardware problem.

Could you rerun with the same B2 and sigma, and see what you get?

Last fiddled with by 10metreh on 2009-08-08 at 07:10
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