Da

1

0.1

0.01

0.001

0.0001

0.00001

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

$c_f$

−0.156954

−0.0979064

0.0180856

0.0860125

0.122236

0.142053

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

$c_f$

−0.241100

−0.184620

−0.0593438

0.0241292

0.0696405

0.0944781

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

$c_f$

0.0020959

0.0705451

0.180369

0.221909

0.234224

0.239089