xiejie.cpp

弦截法——数值分析,程序代码

// diedai.cpp : Defines the entry point for the console application.
//
//第104页24题：用弦接法求方程的根
#include "stdafx.h"
#include "iostream.h"
#include "math.h" 


double f(double i)
{
	double n;
	n=i*i*i+2*i*i+10*i-20;
	return n;
}
double fun(double x)
{
	double m;
	m=x-(f(x)*(x-1.0))/(f(x)-f(1.0));
	return m;
}

int main(int argc, char* argv[])
{
	int k=0,N;
	double x0=1.0,x1=1.5384,x2;	
	cout<<"求方程x*x*x+2*x*x+10*x-20=0的根"<<endl;
	cout<<"输入需要迭代的次数：";
	cin>>N;

	for(;k<=N;k++)
	{
		x2=fun(x1);	
		if(fabs(x2-x1)<0.000001)
			break;
		x1=x2;
	}
	cout<<"求出的根为x="<<x2<<endl;
	return 0;
}