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

Table 3

The experimentally optimal parameters and the corresponding spectral radii for the iteration matrices of GPMHSS and DGPMHSS with 𝑉=𝑊−𝑇 and 𝑚=24.

	𝜎2
	10	50	80	100
GPMHSS
𝛼^∗𝐺	1.1	1.5	2.2	1.6
𝜌(𝑀𝛼^∗𝐺)	0.5011	0.5234	0.5708	0.6360
DGPMHSS
𝛼^∗𝐷	1.1	1.5	2.2	1.8
𝛽^∗𝐷	1	1	1	1
𝜌(𝑀𝛼^∗𝐷,𝛽^∗𝐷)	0.5005	0.5081	0.5289	0.5091