Table 7 \(L^{2}\)-norm and convergence rate when \(\beta =\gamma =0.3,0.5, 0.8\) and \(\tau =h\)

1/2⁴

4.4709e−05

–

4.2333e−05

–

4.1909e−05

–

1/2⁵

1.1928e−05

1.9062

1.1359e−05

1.8979

1.1269e−05

1.8949

1/2⁶

3.0803e−06

1.9532

2.9441e−06

1.9479

2.9313e−06

1.9427

1/2⁷

7.8459e−07

1.9731

7.5093e−07

1.9711

7.4905e−07

1.9684

1/2⁸

1.9835e−07

1.9839

1.8995e−07

1.9831

1.8966e−07

1.9816