Fast Algorithms for for Linear Algebra Modulo N

  • Authors:
  • Arne Storjohann;Thom Mulders

  • Affiliations:
  • -;-

  • Venue:
  • ESA '98 Proceedings of the 6th Annual European Symposium on Algorithms
  • Year:
  • 1998

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Abstract

Many linear algebra problems over the ring ZN of integers modulo N can be solved by transforming via elementary row operations an n × m input matrix A to Howell form H. The nonzero rows of H give a canonical set of generators for the submodule of (ZN)m generated by the rows of A. In this paper we present an algorithm to recover H together with an invertible transformation matrix P which satisfies PA = H. The cost of the algorithm is O(nmω-1) operations with integers bounded in magnitude by N. This leads directly to fast algorithms for tasks involving ZN-modules, including an O(nmω-1) algorithm for computing the general solution over ZN of the system of linear equations xA = b, where b ∈ (ZN)m.