C#中如何开根号

Answer 1

/*1.模拟笔算开平放的整数开平方算法：*/
int _sqrti(int n)
{
int r,l,t; //r: 方根; l: 余数; t: 试除数;
if(n<100)
{
r = 9;
while(n < r*r) r--;
}
else
{
r = _sqrti(n/100);
l = n - r*r*100;
t = l/(r*20);
while( t*(r*20 + t) > l ) t--;
r = r*10 + t;
}
return r;
}

/*2. 迭代法:
迭代公式：x[n+1]=(x[n]+y/x[n])/2
可以证明，x[n]收敛到y^(1/2)，而且收敛速度较快。
*/
double _sqrt(double y)
{
#define eps 1e-15
double x1,x2;
if(y<eps) return 0;
x2= y>1.0? y/2 : y*2;
do{
x1 = x2;
x2 = (x1 + y/x1)/2;
}while(fabs(x2-x1) > eps);
return x2;
#undef eps
}
参考资料：http://doc.zhaoci.com/archives/structure/841043ea0354d6be0d739a1c232b4081.php

Answer 2

c#中使用开平方函数
line=System.Math.Sqrt((ending.x-starting.x)*(ending.x-starting.x)+(ending.y-starting.y)*(ending.y-starting.y));
具体方式：
Console.WriteLine(Math.Sqrt(2.0)); //1.4142135623731
Console.WriteLine(Math.Pow(2, 2)); //4
Console.WriteLine(Math.Pow(9, 0.5)); //3
Console.WriteLine(Math.Pow(125, (1.0/3.0))); //5

Answer 3

#region Using Directives
using System;
#endregion

class Tester
{
static void Main()
{
double i = System.Math.Sqrt(5);
Console.WriteLine(i);
}
}