牛顿法求平方根可拓展

int mySqrt(int x) {
    double t=1.0;         //初始迭代值
    double cheak;    //误差
    double p = 1e-2;        //误差上限
    do
    {
        t = (x / t + t) / 2.0;
        cheak = t * t - x;
    } while((cheak >= 0 ? cheak : -cheak) > p);
    return (int)t;
}

double myCube(int x) {
    double t=1.0;
    double cheak;
    double p = 1e-5;
    do
    {
        t = (x / pow(t,2) + 2*t) / 3.0;
        cheak = pow(t,3) - x;
    } while((cheak >= 0 ? cheak : -cheak) > p);
    return t;
}

原文地址：https://www.cnblogs.com/czsblog/p/11156592.html