bisec2lab

#include<bits/stdc++.h>
#define E 0.0001
using namespace std;

double func(double x){

return x*x*x-x-1;
}
int n=1;
double c;
void bisection(double a,double b){

if(func(a)*func(b)>0){

    cout<<"roots does not exit"<<endl;
    return;
}

while ((b-a)>=E){
      c=(a+b)/2;
    if(func(c)*func(a)<0){
        cout<<"approximation is:"<<n<<" : "<<c<<endl;
        //cout<<"functional value:"<<c*c*c-c-1<<endl;
        b=c;
    }
    else{
          cout<<"approximation is:"<<n<<" : "<<c<<endl;
        //cout<<"functional value:"<<c*c*c-c-1<<endl;

        a=c;}

n++;
cout<<endl;
}}

int main(){
cout<<"please enter input:";
double a,b;
cin>>a>>b;
bisection(a,b);
cout<<"the required root="<<c<<endl;

}