New Preconditioners with Two Variable Relaxation Parameters for the Discretized Time-Harmonic Maxwell Equations in Mixed Form

Table 3

Iteration counts for different meshes, using BiCGSTAB with the preconditioner 𝑀_{𝑘,𝜂,𝜀} satisfying 𝜂−𝑘²=0.1 and −1/𝜀=𝜂−𝑘². The iteration was stopped once ‖𝑟^(𝑘)‖/‖𝑟⁽⁰⁾‖≤5×10⁻¹⁰.

Mesh	𝑘^2=0	𝑘^2=0.25	𝑘^2=0.5	𝑘^2=1	𝑘^2=3	𝑘^2=4	𝑘^2=6	𝑘^2=10
8×8	2	2.5	2.5	2.5	3.5	4	4.5	5.5
16×16	2	2.5	2.5	2.5	3.5	4	4.5	5
32×32	2	2.5	2.5	2.5	3.5	4	4.5	5.5
64×64	2	2.5	2.5	2.5	3.5	4	5	5.5
128×128	2	2.5	3	3	4	4.5	5	6