A sparse H -matrix arithmetic: general complexity estimates
Journal of Computational and Applied Mathematics - Special issue on numerical anaylsis 2000 Vol. VI: Ordinary differential equations and integral equations
Nested Dissection: A Survey
Fast algorithms for spectral collocation with non-periodic boundary conditions
Journal of Computational Physics
Some Fast Algorithms for Sequentially Semiseparable Representations
SIAM Journal on Matrix Analysis and Applications
SIAM Journal on Scientific Computing
Structures Preserved by Schur Complementation
SIAM Journal on Matrix Analysis and Applications
A Fast $ULV$ Decomposition Solver for Hierarchically Semiseparable Representations
SIAM Journal on Matrix Analysis and Applications
A Givens-Weight Representation for Rank Structured Matrices
SIAM Journal on Matrix Analysis and Applications
Robust Approximate Cholesky Factorization of Rank-Structured Symmetric Positive Definite Matrices
SIAM Journal on Matrix Analysis and Applications
Parallel design and performance of nested filtering factorization preconditioner
SC '13 Proceedings of the International Conference on High Performance Computing, Networking, Storage and Analysis
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For a given symmetric positive definite matrix $A\in\mathbf{R}^{N\times N}$, we develop a fast and backward stable algorithm to approximate $A$ by a symmetric positive definite semiseparable matrix, accurate to a constant multiple of any prescribed tolerance. In addition, this algorithm preserves the product, $AZ$, for a given matrix $Z\in\mathbf{R}^{N\times d}$, where $d\ll N$. Our algorithm guarantees the positive-definiteness of the semiseparable matrix by embedding an approximation strategy inside a Cholesky factorization procedure to ensure that the Schur complements during the Cholesky factorization all remain positive definite after approximation. It uses a robust direction-preserving approximation scheme to ensure the preservation of $AZ$. We present numerical experiments and discuss the potential implications of our work.