# C++ Program for Newton-Raphson Method to find the roots of an Equation

```//Newton-Raphson Method
#include<iostream>
#include<cmath>
#include<iomanip>
using namespace std;
double f(double x);    //declare the function for the given equation
double f(double x)    //define the function here, ie give the equation
{
double a=pow(x,3.0)-x-11.0;    //write the equation whose roots are to be determined
return a;
}
double fprime(double x);
double fprime(double x)
{
double b=3*pow(x,2.0)-1.0;        //write the first derivative of the equation
return b;
}
int main()
{
double x,x1,e,fx,fx1;
cout.precision(4);        //set the precision
cout.setf(ios::fixed);
cout<<"Enter the initial guess\n";    //take an intial guess
cin>>x1;
cout<<"Enter desired accuracy\n";    //take the desired accuracy
cin>>e;
fx=f(x);
fx1=fprime(x);
cout <<"x{i}"<<"    "<<"x{i+1}"<<"        "<<"|x{i+1}-x{i}|"<<endl;

do
{
x=x1;                /*make x equal to the last calculated value of                             x1*/
fx=f(x);            //simplifying f(x)to fx
fx1=fprime(x);            //simplifying fprime(x) to fx1
x1=x-(fx/fx1);            /*calculate x{1} from x, fx and fx1*/
cout<<x<<"     "<<x1<<"           "<<abs(x1-x)<<endl;
}while (fabs(x1-x)>=e);            /*if |x{i+1}-x{i}| remains greater than the desired accuracy, continue the loop*/
cout<<"The root of the equation is "<<x1<<endl;
return 0;
}

//output attached as jpg

```

Explanation of the code: [wpedon id="7041" align="center"]

## 6 thoughts on “C++ Program for Newton-Raphson Method to find the roots of an Equation”

1. Good one !!!!!

1. Thanks! Appreciate your feedback.

2. how we copute tax=x=

2. tns bro

3. It gives only x1 answers.how can I get the final result

4. and what are the errors in each approach?