二分法程序

#include<iostream.h>
#include<math.h>
int m;
double x1,x2,x3,f();
double f(double x) 
{
     double y;
            y=x*x*x-x-1;
     return y;
}
double main()
{   double a,b;
    double x;
       cout<<"please input two number a,b"<<endl;
       cin>>a>>b;

double x1=a;
double x2=b;
double x3;
        
 for(int i=1;;i++)
{
 if(f(x1)==0)
   {m=(int)(x1*100);x1=m/100; 
       cout<<"方程的根是x="<<x1<<"，迭代次数="<<i<<endl;
   }
   if(f(x2)==0)
 {m=(int)(x2*100);x2=m/100; 
 cout<<"方程的根是x="<<x2<<"，迭代次数="<<i<<endl;
 }