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Theory and Modern Applications

Table 5 Comparison of the \(L^{2}\) errors and convergence order on different grid level of MG and EXFMG methods for Example 5.1

From: An extrapolation full multigrid algorithm combined with fourth-order compact scheme for convection–diffusion equations

j

\(\Omega _{j}\)

MG

EXFMG

\(\Vert u-u_{j}^{*} \Vert _{\infty }\)

Order

\(\Vert u-\bar{u}^{*}_{j} \Vert _{\infty }\)

Order

\(\Vert u-u_{j}^{*} \Vert _{\infty }\)

Order

2

64 × 64

5.97E−04

5.97E−04

7.81E−05

3

128 × 128

3.84E−05

3.96

3.84E−05

3.96

1.35E−06

5.85

4

256 × 256

2.41E−06

3.99

2.41E−06

3.99

2.17E−08

5.96

5

512 × 512

1.51E−07

4.00

1.51E−07

4.00

3.41E−10

5.99

6

1024 × 1024

9.45E−09

4.00

9.45E−09

4.00

6.27E−12

5.77