10 papers
Broken-space Additive Schwarz Mass Inverse Approximations and (Block) Preconditioning
Oliver A. Krzysik, Ben S. Southworth, Golo A. Wimmer
The paper proposes a broken-space additive Schwarz (BRAS) method to approximate the inverse of finite-element mass matrices, showing it improves conditioning and reduces solve time…
Two-level convergence of Algebraic Multigrid with Overlapping Smoothers and Spectral Coarse Grids
O. A. Krzysik, B. S. Southworth, H. Al Daas
We recently developed the least-squares algebraic-multigrid domain-decomposition (LS-AMG-DD) solver as an algebraic multilevel method for sparse symmetric positive definite matrice…
Parallel-in-iteration optimization using multigrid reduction-in-time
G. H. M. Araújo, O. A. Krzysik, H. De Sterck
Standard gradient-based iteration algorithms for optimization, such as gradient descent and its various proximal-based extensions to nonsmooth problems, are known to converge slowl…
Parallel-in-time solution of scalar nonlinear conservation laws
O. A. Krzysik, H. De Sterck, R. D. Falgout +1
We consider the parallel-in-time solution of scalar nonlinear conservation laws in one spatial dimension. The equations are discretized in space with a conservative finite-volume m…
Parallel-in-time solution of hyperbolic PDE systems via characteristic-variable block preconditioning
O. A. Krzysik, H. De Sterck, R. D. Falgout +1
We consider the parallel-in-time solution of hyperbolic partial differential equation (PDE) systems in one spatial dimension, both linear and nonlinear. In the nonlinear setting, t…
Optimal transfer operators in algebraic two-level methods for nonsymmetric and indefinite problems
Oliver A. Krzysik, Ben S. Southworth, Golo A. Wimmer +3
Consider an algebraic two-level method applied to the -dimensional linear system using fine-space preconditioner (i.e., ``relaxation'' or ``smoother'…