牛顿迭代.cpp

计算方法的4个小程序,牛顿插值,lagrange插值,牛顿迭代,改进欧拉公式

# include<iostream.h>
# include<math.h>

double f(double x)
{ 
	return pow(x,3)+10*x-20;
}
double g(double x)
{ 	
	return 3*pow(x,2)+10;
}

void main(void)
{
	double x,e,t;
	int n=1;
	cout<<"请输入初值x:";
	cin>>x;
	cout<<"请输入精度e:";
	cin>>e;
	t=0;
	while(fabs(x-t)>e){
	t=x;
	x=x-f(x)/g(x);
	}
	cout<<"用牛顿迭代得到方程的根为：x="<<x<<endl;
}