#include <stdio.h>
#include <stdlib.h>
int main(int argc, char *argv[]) {
int m, n, i;
double sum = 0;
printf("Please input a number:");
scanf("%d", &m);
printf("Please input another number:");
scanf("%d", &n);
if (m > n || m <= 0) // m大于0 且小于n
return 1;
for(i=m;i<=n;i++)
sum = sum + i*i + 1.0/i; // 必须是1.0，不然就成了整数运算，小数被舍弃
printf("∑= %.6lf", sum);
return 0;
}
