Preconditioned Krylov Subspace Methods for Sixth Order Compact Approximations of the Helmholtz Equation

Table 7

3D Dirichlet-Sommerfeld problem.

Grid size (ℎ)	GMRES	SKS	Err6	Err2
1/64	6	9	1.25∗10^−06	1.35∗10^−03
1/128	4	7	1.84∗10^−08	3.23∗10^−04
1/256	3	5	2.82∗10^−10	7.99∗10^−05