Table 1 The results of the algorithm in [20]

$x_1$

2

1.8602

1.8441

1.8074

1.7919

1.7878

1.7843

1.7800

$x_2$

3

2.7902

2.7662

2.7112

2.6878

2.6817

2.6765

2.6700