大佬们可不可以帮我解答一下，谢谢

#include <stdio.h>

double recursion(int n);

int main()
{
    double sum=0;
    int n=1;

    sum=recursion(n);
    printf("sum=%lf",sum);
    return 0;
}

double recursion(int n)
{
    //printf("n=%lf\n",(double)1.0/n);
    if((double)1.0/n<(1e-4))
        return (double)1.0/n;
    else
        return (double)1.0/n+recursion(n+1);
}