$\tau$

$\alpha =1.1$

$\alpha =1.5$

$\alpha =1.9$

${\Vert e\Vert }_{L_2}$

order

${\Vert e\Vert }_{L_2}$

order

${\Vert e\Vert }_{L_2}$

order

1/10

1.0164e−05

1.7063e−04

2.9610e−03

1/20

2.5498e−06

1.9950

4.2836e−05

1.9939

7.7633e−04

1.9313

1/30

1.1340e−06

1.9983

1.9061e−05

1.9970

3.4568e−04

1.9953

1/40

6.3809e−07

1.9988

1.0727e−05

1.9983

1.9456e−04

1.9979

1/50

4.0844e−07

1.9993

6.8673e−06

1.9986

1.2455e−04

1.9988