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

Table 8

3D Dirichlet-Sommerfeld problem (different 𝑘²).

	𝑘=10	𝑘=20	𝑘=30	𝑘=40	𝑘=50	𝑘=35.7+0.43𝑖
ℎ=1/64	5∣7	6∣9	11∣43	16∣div	119∣div	14∣54
ℎ=1/128	4∣5	4∣7	7∣8	7∣div	12∣11	7∣9
ℎ=1/256	3∣4	3∣5	5∣6	5∣6	6∣7	5∣6
ℎ=1/512	2∣4	3∣5	4∣5	3∣5	4∣6	4∣5
𝜓	15	13	13	15	11	13