功能:Polylogarithm函数求解

格式:
PolylogarithmLi(s,z,n)
PolylogarithmLi(s,z)
s:看说明
z:看说明
n:求解的循环次数,默认为1000

说明:PolylogarithmLi(s,z)=sum[z^i/i^s,i=1,2,3,……,∞]

参考:{Polylogarithm Function<http://en.wikipedia.org/wiki/Polylogarithm>}

例子:

a=PolylogarithmLi(-1,2+i)//回车得到如下结果
a = 0.500000000000002 - 0.999999999999997i

b=PolylogarithmLi(i,3i)//回车得到如下结果
b = -2.21115363156854 - 0.444652808048018i