用牛顿迭代法求a^(1/3)

//用牛顿迭代法求a^(1/3)
#include <iostream>
#include <cmath>
using namespace std;
int main()
{
    const double EPS = 1e-6;//精度
    double  a,x1,x2;
    cout<<"请输入a："<<endl;
    cin>>a;
    x2=a;//第一个值取a
    do
    {
        x1=x2;
        x2=(2*x1+a/(x1*x1))/3;//计算新值
    }
    while (fabs(x2-x1)>=EPS);//控制精度
    cout << a<<"的立方根是：" <<x2<< endl;
    return 0;
}
//用牛顿迭代法求a^(1/3)
#include <iostream>
#includ