#include <stdio.h>
void Calulate(double deg)
{
int i = 1;
double x = 0, tmp = 1.0;
while(1.0/tmp > deg)
{
tmp *= (2.0*i);
x += (1.0/tmp);
i++;
}
printf("i = %d, x = %.9lf\n", i, x);
}
int main()
{
Calulate(1E-4);
Calulate(1E-8);
Calulate(1E-10);
return 0;
}