Table 2.

Comparison of computational costs.

	RMS	h (mm)	Assemble (sec)	Propagation (sec)
σ = 0.5
FDM	3.30e − 04	0.05	n/a	258.31
FEM	2.31e − 04	0.05	0.20	248.26
EFGM(cubic, d max⁡ = 1.5)	4.56e − 04	0.2	0.11	39.50
EFGM(cubic, d max⁡ = 2.0)	2.60e − 04	0.8	0.05	41.33
EFGM(quartic, d max⁡ = 1.5)	3.40e − 04	0.2	0.07	38.83
EFGM(quartic, d max⁡ = 2.0)	1.49e − 04	0.8	0.04	40.60
σ = 0.25
FDM	6.06e − 04	0.05	n/a	580.11
FEM	4.60e − 04	0.05	0.21	591.42
EFGM(cubic, d max⁡ = 1.5)	8.12e − 04	0.2	0.10	48.23
EFGM(cubic, d max⁡ = 2.0)	5.80e − 04	0.8	0.04	50.90
EFGM(quartic, d max⁡ = 1.5)	5.20e − 04	0.2	0.08	47.81
EFGM(quartic, d max⁡ = 2.0)	3.00e − 04	0.8	0.02	50.90