The Faddeev-LeVerrier algorithm and the Pfaffian

Abstract

We adapt the Faddeev-LeVerrier algorithm for the computation of characteristic polynomials to the computation of the Pfaffian of a skew-symmetric matrix. This yields a very simple, easy to implement and parallelize algorithm of computational cost $O(n^{\beta+1})$ where $n$ is the size of the matrix and $O(n^{\beta})$ is the cost of multiplying $n\times n$-matrices, $\beta\in[2,2.37286)$. We compare its performance to that of other algorithms and show how it can be used to compute the Euler form of a Riemannian manifold using computer algebra.