java - Cube Root 使用迭代和二分法

Question

我试图通过二等分然后缩小它来找到一个数字的立方根。我以这种方式有平方根的程序，但立方根方法只是继续循环并且永远不会给出答案。我不确定我哪里出错了，需要一些建议。

public class myFunc
{
    public static double squareRoot(double value, double precision)
    {
        double low, high, middle;
        high = 1;
        low = value;
        middle = (high + low) / 2;
        Console.WriteLine("{0,20:n12}{1,20:n12}{2,20:n12}", low, middle, high);
        while ((high-low)>precision)
        {
            if ((middle * middle) <value)
            {
                low = middle;
            }
            else
            {
                high = middle;
            }
            middle = (high + low) / 2;
            Console.WriteLine("{0,20:n12}{1,20:n12}{2,20:n12}", low, middle, high);
        }
        return (middle);
    }

    public static double cubeRoot(double value, double precision)
    {
        double low, high, middle;

        high = value;
        low = 1;
        middle = (high + low) / 3;
        Console.WriteLine("{0,20:n12} {1,20:n12} {2,20:n12}", low, middle, high);
        while ((high - low) > precision)
        {
            if ((middle * middle*middle)>value)
            {

                high = middle;
            }

            else
            {
                low = middle;
            }
            middle = (high + low) / 3;
            Console.WriteLine("{0,20:n12} {1,20:n12} {2,20:n12}", low, middle, high);
        }
        return (middle);
    }

标签： javarootcubebisection

Answer 1

middle = (high + low) / 3;假设高是10，低是8，中间是...... 6？这不是超出你想要的范围吗？

中间应该仍然是(high + low) / 2，搜索第三根的只是(middle * middle*middle)>value测试。