20080118, 11:05  #1 
(loop (#_fork))
Feb 2006
Cambridge, England
2×7×461 Posts 
ggnfs lattice siever misses some primes
We have f(a,b) = 1361*a^6b^6, g(a,b) = a1361^7*b
The siever in GGNFS outputs the line 417266,227287:22061,2e64f,e9c75,6f1,dde715:13b08b,d8d,1273,4eb5,4c1,b732f,cf0671 and msieve relationparsing gives an error 15 (wrong factors) Converting from hex, the line says rationalside factors 139361, 190031, 957557, 1777, 14542613 algebraicside factors 1290379, 3469, 4723, 20149, 1217, 750383, 13567601 gp says Code:
? factor(A1361^7*B) %5 = [1 1] [3 1] [1777 1] [139361 1] [190031 1] [957557 1] [14542613 1] ? factor(1361*A^6B^6) %3 = [1217 1] [1361 1] [3469 1] [4723 1] [20149 1] [750383 1] [1290379 1] [13567601 1] This isn't a serious issue, it cost about 0.5% of the relations on a small calculation, but I tend to want to diagnose all 15 relationreading messages, given what a mess a wrong factorisation could cause in the matrix stage. Last fiddled with by fivemack on 20080118 at 11:06 
20080118, 13:47  #2  
"Bob Silverman"
Nov 2003
North of Boston
2^{2}·1,877 Posts 
Quote:
The code is probably not handling projective primes properly. Or perhaps not at all. 

Thread Tools  
Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
QS Lattice Siever  R.D. Silverman  Factoring  31  20181008 17:17 
Compiling 64 bit lattice siever on gcc 4.8.5  chris2be8  Factoring  6  20180206 17:22 
OpenCL accellerated lattice siever  pstach  Factoring  1  20140523 01:03 
Shape of a CUDA lattice siever  fivemack  Programming  2  20121216 01:07 
Msieve / lattice siever with degree 7/8 poly  Batalov  Msieve  54  20100113 19:45 