Milne’s Method C++

#include<iostream>
#include<iomanip>
#include<cmath>
using namespace std;

float x[5],y[5],h;

float f(int i)
{
return x[i]-y[i]*y[i];
}

void corect()
{
y[4]=y[2]+(h/3)*(f(2)+4*f(3)+f(4));
cout<<setw(23)<<" ";
cout<<setprecision(4)<<setw(8)<<y[4];
cout<<setw(8)<<f(4)<<endl;
cout<<" "<<y[4]<<" "<<f(4);
}

int main()
{
float xr,aerr,yc;
int i;

cout<<"Enter the value of x0,xr,h allowed error"<<endl;
cin>>x[0]>>xr>>h>>aerr;

cout<<"enter the value of y[i],i=0,3"<<endl;
for(i=0;i<=3;i++)
cin>>y[i];
cout<<fixed;

for(i=1;i<=3;i++)
x[i]=x[0]+i*h;

cout<<setw(5)<<"x"<<setw(15)<<"Predicted";
cout<<setw(17)<<"Corrected"<<endl;

cout<<setw(11)<<"y"<<setw(10)<<"f";
cout<<setw(7)<<"y"<<setw(10)<<"f"<<endl;

while(1)
{
if(x[3] >= xr)
return 0;
x[4] = x[3]+h;
y[4] = y[0]+(4*h/3)*(2*(f(1)+f(3)-f(2)));

cout<<setw(6)<<setprecision(2)<<x[4];
cout<<setprecision(4)<<setw(8)<<y[4];
cout<<setw(4)<<f(4)<<endl;

corect();

while(1)
{
yc = y[4];
corect();

if(fabs(yc-y[4]) <= aerr)
break;
}

for(i=0;i<=3;i++)
{
x[i] = x[i+1];
y[i] = y[i+1];
}
}
}