Work

A Simple and Fast Algorithm for Computing the $N$-th Term of a Linearly Recurrent Sequence

Year: 2020
Type: preprint
Abstract: We present a simple and fast algorithm for computing the $N$-th term of a given linearly recurrent sequence. Our new algorithm uses $O(\mathsf{M}(d) \log N)$ arithmetic operations, where $d$ is the order of the recurrence, and $\mathsf{M}(d)$ denotes the number of arithmetic operations for computing the product of two polynomials of degree $d$. The state-of-the-art algorithm, due to Charles Fiduccia (1985), has the same arithmetic complexity up to a constant factor. Our algorithm is simpler, faster and obtained by a totally different method. We also discuss several algorithmic applications, notably to polynomial modular exponentiation, powering of matrices and high-order lifting.
Language: English
Open Access status: green
OpenAlex ID: W3068385242
Cites: 56
Cited by: 1
Related to: 10