C++ program for Newton-Raphson Method

#include<iostream.h>
#include<conio.h>
#include<math.h>
#define EPS 0.000001
#define MAXIT 20
#define F(x) (x)*(x)*(x)+(x)*(x)-3*(x)-3
#define FD(x) 3*(x)*(x)+2*(x)-3

void main(){
clrscr();
int count;
float x0, xn, fx, fdx, fxn;
cout<<"             NEWTON RAPHSON'S METHOD";
   cout<<endl<<"x^3+x^2-3x-3";
cout<<endl<<"Enter the initial value of x:";
cin>>x0;
count=1;

begin:
fx=F(x0);
fdx=FD(x0);
xn=x0-fx/fdx;
if (fabs((xn-x0)/xn) < EPS){
cout<<"Approximate Root: "<<xn<<endl;
fxn =F(xn);
cout<<"Functional Value: "<<fxn<<endl;
cout<<"No. of Iterations: "<<count<<endl;
}
else{
x0=xn;
count=count+1;
if(count<MAXIT){
goto begin;
}
else{
cout<<"SOLUTION DOES NOT CONVERGE!!"<<endl;
cout<<"Iterations: "<<MAXIT<<endl;
}
}
getch();
}

Sample Output:

                    NEWTON RAPHSON’S METHOD

x^3+x^2-3x-3

Enter the initial value of x:2

Approximate Root: 1.73205

Functional Value: -2.94213e-07

No. of Iterations: 4

©Dixit Bhatta 2013