编程求方程的根

 

//此程序用于求方程的一个根

//用一个点类的好处是:能够做到对各个点的封装,使之受其它的点的干扰

#include<iostream.h>
#include<math.h>
float function(float x)
{
 return x*x-6*x;
}
class Point
{
 public:
  float x;
  float y;
 public:
  Point()
  {
   cout<<"无参构造"<<endl;
  
  }
   Point(const float& a,const float& b):x(a),y(b){cout<<"有参构造"<<endl;}
   friend float Zero(Point& a,Point& b)
   {
    float y=a.x-(a.y*((a.x-b.x)/(a.y-b.y)));
        cout<<y<<endl;
        return y;
   }
  friend void Initialize(Point& a,Point& b)
  {
     while(1)
  {
  cout<<"请输入两个x值f(x)的符号相异(否则重新输入))"<<endl;
  cin>>a.x>>b.x;
  if(function(a.x)*function(b.x)<0)
   break;
  }
     a.y=function(a.x);
  b.y=function(b.x);
  }
};

float Solve(Point& a,Point& b)
{
 float x=Zero(a,b);
 float y=function(x);
 Point temp(x,y);
 if(fabs(y)<1e-6)
 {
 
         return x;
 }
 else
 {
  if(temp.y*a.y>0)//换同号的点

  {
   a.x=temp.x;
   a.y=temp.y;
  }
  else
  {
   b.x=temp.x;
   b.y=temp.y;
  }
    float result=Solve(a,b);
    
    return result;//这些返回值都是起承接作用的,将各个函数的结果连接上

 }
}
void main()
{
 
 Point a,b;
 Initialize(a,b);
 cout<<"方程x*x-6*x=0的根是:"<<endl;
  cout<<Solve(a,b);
}