A scalable Helmholtz solver combining the shifted Laplace preconditioner with multigrid deflation

A Helmholtz solver whose convergence is parameter independent can be obtained by combining the shifted Laplace preconditioner with multigrid deflation. To proof this claim, we develop a Fourier analysis of a two-level variant of the algorithm proposed in [1]. In this algorithm those eigenvalues that prevent the shifted Laplace preconditioner...

Fast iterative solution methods for the Helmholtz equation