Newton迭代法的C++实现

#include<iostream>
#include<math.h>
using namespace std;

//1.编制Newton法解方程f(x) = 0的通用程序

float func_x(float x);             //函数声明
float diff_func(float x);

int main()
{
	float x0, e1, x1,tol;
	int cont = 1;
	cout << "Please input a root and a limit value：" << endl;
	cin >> x0 >> e1;                                                   //输入迭代初值和误差极限
	x1 = x0 - func_x(x0) / diff_func(x0);                  
	tol = fabs(x1 - x0);

	while (tol > e1)                                                    //大于误差极限继续进行迭代
	{
		cout << "The " << cont << " times of NewtonIteration root is: " << x1 << endl;
		x0 = x1;
		x1 = x0 - func_x(x0) / diff_func(x0);                           //迭代算法
		tol = fabs(x1 - x0);
		cont++;                                                         //迭代次数计算
	}
	cout << "The final root of Iteration is: " << x0 << endl;
	return 0;

}

float func_x(float x)                                                  //原函数
{
	float a = 1.0;
	return (a/3 * x * x * x - x);
}

float diff_func(float x)                                              //函数求导
{
	return (x * x - 1);
}