Da

1

0.1

0.01

0.001

0.0001

0.00001

$\begin{array}{l}\eta =1/3\\ \xi =2/3\end{array}$

$c_f$

−0.1538176

−0.153*

−0.07977407

0.04941739

0.049*

0.1152168

−0.1436413

−0.1562024

$\begin{array}{l}\eta =1/4\\ \xi =3/4\end{array}$

$c_f$

−0.2365115

−0.1575664

−0.01321413

0.06447045

0.0981652

0.1129008

$\begin{array}{l}\eta =0.49\\ \xi =0.51\end{array}$

$c_f$

0.0022864

0.002*

0.0715832

0.1820249

0.182*

0.2237071

0.2361822

0.2409651