A BDDC Preconditioner for the Rotated 𝑄₁ FEM for Elliptic Problems with Discontinuous Coefficients

Table 1

The number of iterations and condition numbers.

𝑀×𝑀	𝐻/ℎ=4			𝐻/ℎ=16
	𝑘=2	𝑘=4	𝑘=6	𝑘=2	𝑘=4	𝑘=6
4×4	9 (2.68)	9 (2.87)	9 (2.87)	11 (3.84)	11 (3.83)	11 (3.76)
8×8	10 (2.78)	10 (2.74)	10 (2.73)	13 (4.25)	13 (4.16)	13 (4.17)
16×16	10 (2.86)	11 (2.84)	12 (2.83)	13 (4.39)	14 (4.34)	14 (4.34)
32×32	10 (2.89)	11 (2.86)	12 (2.84)	13 (4.45)	13 (4.45)	14 (4.39)