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Special number field sieve

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The special number field sieve (SNFS) is a special-purpose factorization algorithm. The general number field sieve (GNFS) was derived from it.

The special number field sieve is efficient for integers of the form re ± s, where r and s are small. In particular, it is ideal for factoring Mersenne numbers.

Its running time, in asymptotic notation, is conjectured to be:

[math]\displaystyle{ \Theta\left(\exp\left( \left(\frac{32}{9}n\right)^{\frac{1}{3}} (\log n)^{\frac{2}{3}} \right)\right). }[/math]

The SNFS has been used extensively by NFSNET (a volunteer distributed computing effort) and others to factorise numbers of the Cunningham project.

The first step is the polynomial selection.

See also

External links

  • Special number field sieve
  • GGNFS, developed by Chris Monico, containing Kleinjung/Franke polynomial selection and Jens Franke's lattice siever.
  • Msieve, developed by Jason Papadopoulos, having sophisticated postprocessing.