Title
Perturbation Analysis of the QR factor R in the context of LLL lattice basis reduction.
Abstract
In 1982, Arjen Lenstra, Hendrik Lenstra Jr. and Laszlo Lovasz introduced an efficiently computable notion of reduction of basis of a Euclidean lattice that is now commonly referred to as LLL-reduction. The precise definition involves the R-factor of the QR. factorization of the basis matrix. In order to circumvent the use of rational/exact arithmetic with large bit-sizes, it is tempting to consider using floating-point arithmetic with small precision to compute the R-factor. In the present article, we investigate the accuracy of the factor R of the QR factorisation of an LLL-reduced basis. Our main contribution is the first fully rigorous perturbation analysis of the R-factor of LLL-reduced matrices under columnwise perturbations. Our results are very useful to devise LLL-type algorithms relying on floating-point approximations.
Year
DOI
Venue
2012
10.1090/S0025-5718-2012-02545-2
MATHEMATICS OF COMPUTATION
Keywords
Field
DocType
lattice reduction,LLL,QR factorization,perturbation analysis
Discrete mathematics,Lattice (order),Perturbation theory,Matrix (mathematics),Factorization,Euclidean geometry,Mathematics,QR decomposition,Lattice reduction
Journal
Volume
Issue
ISSN
81
279
0025-5718
Citations 
PageRank 
References 
9
0.74
15
Authors
3
Name
Order
Citations
PageRank
Xiao-Wen Chang120824.85
Damien Stehlé2126973.95
Gilles Villard356548.04