为什么n=9可以算，n=10时就不行了？

n = 10
r = 15.8
1/(2 Pi) \!\(
\*SubsuperscriptBox[\(\[Integral]\), \(-Pi\), \(Pi\)]\ \(Exp[
I \((r\ Sin[u] - n\ u)\)] \[DifferentialD]u\)\)
1/(2 Pi) \!\(
\*SubsuperscriptBox[\(\[Integral]\), \(-Pi\), \(Pi\)]\ \(Cos[
r\ Sin[u] - n\ u] \[DifferentialD]u\)\)
BesselJ[n, r]
代码如上

1/(2 \[Pi]) NIntegrate[Exp[I (r Sin[u] - n u)], {u, -\[Pi], \[Pi]}]
用NIntegrate代替Integrate