Dynamic normal forms and dynamic characteristic polynomial

  • Authors:
  • Gudmund Skovbjerg Frandsen;Piotr Sankowski

  • Affiliations:
  • Department of Computer Science, University of Aarhus, Aabogade 34, DK-8200 Aarhus N, Denmark;Warsaw University, Poland and University of Rome La Sapienza, Italy

  • Venue:
  • Theoretical Computer Science
  • Year:
  • 2011

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Abstract

We present the first fully dynamic algorithm for computing the characteristic polynomial of a matrix. In the generic symmetric case, our algorithm supports rank-one updates in O(n^2logn) randomized time and queries in constant time, whereas in the general case the algorithm works in O(n^2klogn) randomized time, where k is the number of invariant factors of the matrix. The algorithm is based on the first dynamic algorithm for computing normal forms of a matrix such as the Frobenius normal form or the tridiagonal symmetric form. The algorithm can be extended to solve the matrix eigenproblem with relative error 2^-^b in additional O(nlog^2nlogb) time. Furthermore, it can be used to dynamically maintain the singular value decomposition (SVD) of a generic matrix. Together with the algorithm, the hardness of the problem is studied. For the symmetric case, we present an @W(n^2) lower bound for rank-one updates and an @W(n) lower bound for element updates.