近似计算

#include <stdio.h>int main(){double sum=0.0000;int i;for(i=1;(2*i-1)<=1000000;i++){if((i+1)%2==0){//printf("i1=%d\n",i);//printf("%d\n",2*i-1);sum+=1.000000000/i;//printf("sum=%0.16lf\n",sum);}else{sum-=1.00000000000/i;//printf("i2=%d\n",i);}//printf("%d\n",i);}sum+=1/(2*i-1);printf("%.16lf\n",sum);return 0;}

注意就是是i++计数器的增量要固定