mersenneforum.org Linear algebra in MPQS
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 2007-02-01, 22:56 #1 R1zZ1   Feb 2007 5 Posts Linear algebra in MPQS Hi all, I'm an italian student and I need your support. I'm implementing MPQS with GMP, the implemented sieving algorithm works fine and I obtain the sparse matrix representing the good relations that I can use to solve the linear algebra and find factors. My problem is just to solve the linear algebra. I need a C++ implementation or Pari/GP function that find these solutions using gaussian elimination or lanczos (faster, right?). Thx in advance!
 2007-02-01, 23:20 #2 R1zZ1   Feb 2007 510 Posts I'll also appreciate if you indicate me a C++ library with a function that solves equations system over Z_2. Lidia has a function named solve() but i am not sure that it works with sparse matrix modulo 2 and gives me a valid solution. bye Last fiddled with by R1zZ1 on 2007-02-01 at 23:39
2007-02-02, 06:45   #3
jasonp
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Oct 2004

3·1,163 Posts

Quote:
 Originally Posted by R1zZ1 Hi all, I'm an italian student and I need your support. I'm implementing MPQS with GMP, the implemented sieving algorithm works fine and I obtain the sparse matrix representing the good relations that I can use to solve the linear algebra and find factors. My problem is just to solve the linear algebra. I need a C++ implementation or Pari/GP function that find these solutions using gaussian elimination or lanczos (faster, right?).
Lanczos is much faster than Gauss elimination.

There are several MPQS implementations linked to the sticky at the top of the factoring forum; they all have to solve this problem, and there's plenty of code to browse.

jasonp

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