$\epsilon ={10}^{-5}$

$\epsilon ={10}^{-8}$

N

${\Vert u_i^N-u\Vert }_{\infty }$

r

N

${\Vert u_i^N-u\Vert }_{\infty }$

r

8

0.1779

0.9249

8

0.1779

0.9249

16

0.0937

0.6987

16

0.0937

0.6987

32

0.0577

0.9137

32

0.0577

0.9137

64

0.0306

0.7068

64

0.0306

0.7066

128

0.0188

0.9937

128

0.0188

0.9937

256

0.0094

0.9897

256

0.0094

0.9899

512

0.0047

0.9693

512

0.0047

0.9695

1024

0.0024

0.0024