A Twisted Block Tangential Filtering Decomposition Preconditioner

Table 8

Results for Case 5: anisotropic layers. Top results are in 2D, bottom results are in 3D, 𝐭 is set to be the Ritz vector corresponding to the smallest eigenvalue of 𝐀.

	𝑀𝐼𝐿𝑈		𝑀𝑇𝐹𝐹𝐷		𝑀𝑇𝐵𝑇𝐷		𝑀𝐼𝑇𝐹		𝑀𝐼𝑇𝐵
1/ℎ	iters	error	iters	error	iters	error	iters	error	iters	error
50	99	5.88𝑒−8	53	4.91𝑒−9	48	5.58𝑒−9	11	1.85𝑒−8	10	3.78𝑒−8
100	190	6.73𝑒−7	77	1.26𝑒−8	72	1.53𝑒−8	18	2.77𝑒−7	16	7.84𝑒−7
200	×	×	110	1.13𝑒−8	103	3.03𝑒−8	29	3.85𝑒−8	27	8.38𝑒−8
300	×	×	136	1.69𝑒−8	126	1.55𝑒−8	40	1.09𝑒−7	37	7.40𝑒−8
20	27	1.43𝑒−7	25	1.54𝑒−8	22	1.73𝑒−8	10	4.75𝑒−9	9	1.09𝑒−8
30	34	2.55𝑒−7	27	2.71𝑒−8	27	2.65𝑒−8	11	7.30𝑒−8	10	5.71𝑒−8
40	40	8.14𝑒−7	28	2.48𝑒−8	29	3.11𝑒−8	11	2.82𝑒−7	11	1.15𝑒−7