$T_{h}$	CG-algorithm				PCG-algorithm				E-alg
$T_{h}$	$e_{r}$	mdiv	iters.	CPUt	$e_{r}$	mdiv	iters.	CPUt	CPUt
33 × 33	3.1E−4	−7.6E−09	260	0.25	1.9E−3	−3.4E−6	6	0.03	0.01
65 × 65	1.1E−4	−5.0E−10	498	1.18	6.9E−4	−4.5E−7	7	0.085	0.06
129 × 129	4.0E−5	−2.7E−11	854	7.24	2.4E−4	−5.9E−8	7	0.26	0.73
257 × 257	1.4E−5	−1.6E−12	1688	60.69	8.6E−5	−7.5E−9	7	1.96	15.75