A Twisted Block Tangential Filtering Decomposition Preconditioner

Table 6

Results for Case 4: convective skyscraper problems. 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	95	3.84𝑒−9	139	3.43𝑒−9	×	×	13	5.13𝑒−10	13	4.99𝑒−10
100	173	2.81𝑒−8	×	×	×	×	18	1.67𝑒−9	21	7.82𝑒−9
200	×	×	×	×	×	×	25	4.41𝑒−9	28	2.13𝑒−8
300	×	×	×	×	×	×	28	1.85𝑒−8	34	5.74𝑒−8
10	13	2.80𝑒−9	12	2.39𝑒−9	12	3.83𝑒−9	6	2.31𝑒−10	5	4.56𝑒−9
15	92	3.03𝑒−10	56	3.17𝑒−10	×	×	29	4.51𝑒−10	17	4.83𝑒−11
20	71	2.60𝑒−10	34	6.41𝑒−10	121	8.30𝑒−10	9	2.78𝑒−11	18	6.38𝑒−10
30	116	1.59𝑒−9	108	1.78𝑒−9	×	×	33	3.19𝑒−10	15	3.96𝑒−10