拉格朗日插值

#include <iostream>
using namespace std;
int main()
{
    double x[4]={1.1275,1.1503,1.1735,1.1972};
    double y[4]={0.1191,0.13954,0.15932,0.17903};
    double yy=0;
    double xx=1.13;
    for(int i=0;i<4;i++)
    {
       double p=1;
       for(int j=0;j<4;j++)
       {
           if(j!=i)
           p=p*(xx-x[j])/(x[i]-x[j]);

       }
        yy+=p*y[i];
    }
    cout<<yy<<endl;
    return 0;
}