Rounding-Error Analysis of Multigrid V-Cycles

07/01/2023

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by   Stephen F. McCormick, et al.

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This paper provides a rounding-error analysis for two-grid methods that use one relaxation step both before and after coarsening. The analysis is based on floating point arithmetic and focuses on a two-grid scheme that is perturbed on the coarse grid to allow for an approximate coarse-grid solve. Leveraging previously published results, this two-grid theory can then be extended to general V(μ,ν)-cycles, as well as full multigrid (FMG). It can also be extended to mixed-precision iterative refinement (IR) based on these cycles. An added benefit of the theory here over previous work is that it is obtained in a more organized, transparent, and simpler way.