求PI的值

#include <iostream>#include <cmath>#include <iomanip>using namespace std;int main(){    double PI=0,t=1,i=1;    int n=1;    while(fabs(t)>1e-7)    {                    PI=PI+t;                    n=-n;                    i=i+2;                    t=n/i;    }    PI=PI*4;    cout<<"PI="<<setiosflags(ios::fixed)<<setprecision(6)<<PI<<endl;    return 0;}