1156求π的值

 1 #include<cstdio>
 2 #include<cmath>
 3 using namespace std;
 4 double at(double x)
 5 {
 6     double sum=0;
 7     int n=1,t=1;
 8     double s;
 9     while(s>=1e-6)
10     {
11         s=pow(x,n)/n;
12         s=s*t;
13         sum+=s;
14         t=t*(-1);
15         n=n+2;
16     }
17     
18     return sum;
19 }
20 int main()
21 {
22     double pi;
23     pi=6*at(1/sqrt(3));
24     printf("%lf",pi);
25     return 0;
26 }