#include <stdio.h>
#include <stdlib.h>

main()
{
     float pi,sum=1.0,term;
     int n;
     for (n=2;n<=100;)
     {
         term=n*n/(n*n-1);
         sum=sum*term;
         n=n+2;

     }
     pi=2*sum;
     printf("pi= %f\n",pi);
}


把term=n*n/(n*n-1);换成term=1.0n*n/(n*n-1);结果变化较大不知为什么？？