2 papers
math.OC2020
A Note on Multigrid Preconditioning for Fractional PDE-Constrained Optimization Problems
Harbir Antil, Andrei Dr{ă}g{ă}nescu, Kiefer Green
In this note we present a multigrid preconditioning method for solving quadratic optimization problems constrained by a fractional diffusion equation. Multigrid methods within the…
math.NA2019
On theoretical upper limits for valid timesteps of implicit ODE methods
K. R. Green, G. W. Patrick, R. J. Spiteri
Implicit methods for the numerical solution of initial-value problems may admit multiple solutions at any given time step. Accordingly, their nonlinear solvers may converge to any…