f1[[CurlyPhi]_Rational, s_Rational, [Theta]_Rational,
a_Rational] = (
Sqrt[s](a - s))/((a - s)^2 + a^2 -
2a*(a - s)*Cos[[CurlyPhi] - [Theta]])
NIntegrate[
f1[\[CurlyPhi], s, 4*Pi/20, 1], {\[CurlyPhi], 0, Pi}, {s, 0, 1}]
When Phi equals 0, it cannot be calculated.
Note: the Rate of convergence of Numerical integration is too slow and the integration value is overflow、Indeterminate or Infinity
When Phi equals 4*Pi/20, the result is 4.10626.
Note: the Rate of convergence of Numerical integration is too slow and cannot converge to the specified accuracy
Is there anyone who can help solve this problem? Thank you very much
[1]: https://community.wolfram.com//c/portal/getImageAttachment?filename=微信截图_20230717221515.jpg&userId=2969379
[2]: https://community.wolfram.com//c/portal/getImageAttachment?filename=微信截图_20230717222022.jpg&userId=2969379
