C#查找第N个根 [英] C# Find Nth Root

问题描述

我使用以下方法来计算双精度值的第N个根，但是计算第240个根需要花费大量时间.我发现了有关牛顿方法的信息，但无法将其实现为方法.任何帮助，将不胜感激.

I use below method to calculate Nth Root of double value, but it takes a lot of time for calculating the 240th root. I found out about Newton method, but was not able to implement it into a method. Any help would be appreciated.

static double NthRoot(double A, int N)
{
   double epsilon = 0.00001d;//
   double n = N;
   double x = A / n;
   while (Math.Abs(A-Power(x,N)) > epsilon)
   {
    x = (1.0d/n) * ((n-1)*x + (A/(Power(x, N-1))));
   }
   return x;
}

推荐答案

static double NthRoot(double A, int N)
{
    return Math.Pow(A, 1.0 / N);
}

来自维基百科:

在微积分中，根被视为幂的特殊情况，其中幂是分数:

In calculus, roots are treated as special cases of exponentiation, where the exponent is a fraction:

\sqrt[n]{x} \,=\, x^{1/n} 

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