A Double-Parameter GPMHSS Method for a Class of Complex Symmetric Linear Systems from Helmholtz Equation

Table 1

The experimentally optimal parameters and the corresponding spectral radii for the iteration matrices of GPMHSS and DGPMHSS with 𝑉=𝑊−𝑇 and 𝑚=8.

	𝜎2
	10	50	80	100
GPMHSS
𝛼^∗𝐺	1.1	1.5	2.2	2
𝜌(𝑀𝛼^∗𝐺)	0.5009	0.5222	0.5667	0.6274
DGPMHSS
𝛼^∗𝐷	1.1	1.5	2.2	2
𝛽^∗𝐷	1	0.9	0.8	0.8
𝜌(𝑀𝛼^∗𝐷,𝛽^∗𝐷)	0.5001	0.4986	0.5012	0.4901