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#include "stdafx.h"
#include"math.h"
#include<iostream>
using namespace std;
float Formula(float x)//方程表达式
{
    return x*x*x*x-3*x+1;
}
void main()
{
float a,b,e;                 //区间与精度
float x;             //临时变量
float k;
cout<<"***方程求根二分法***"<<endl;
    cout<<"输入区间[a,b]与精度ε(绝对误差限)"<<endl;
	cout<<"please enter a."<<endl;
	cin>>a;
	cout<<"please enter b."<<endl;
	cin>>b;
	cout<<"please enter e."<<endl;
    cin>>e;
　　float l=0;
	for(int k=0;k<100;k++)
	{
		l=(a+b)/2;
		if(Formula(l)*Formula(b)<0)
			a=l;
		else b=l;
		l=(a+b)/2;
		if(fabs(Formula(l))>0.00001)
		cout<<"the l's result is :"<<l<<" 的分半次数为:"<<k<<endl;
		else break;
	}    
     cout<<"二分次数："<<l<<endl;
     cout<<"所求实根："<<l<<endl;
}