Introduction toÂ Iterative methods:Â There are number of iterative methods like Â Jacobi method, Gaussâ€“Seidel method that has been tried and used successfully in various problem situations. All these methods typically generate a sequence of estimates of the solution which is expected to converge to the true solution.Â Newton-Raphson method is also one of the iterative methods which are used to find the roots of given expression.

### Newton-Raphson Method with MATLAB code:

If point x0 is close to the root a, then a tangent line to the graph of f(x) at x0 is a good approximation the f(x) near a. So the root of the tangent line, where the line cuts the X-axis; x1 is the better approximation to a than x0 is.

Slope of the tangent =

Therefore

Repeating process, we obtain a better approximation,

Continue in this way. If xn is the current estimate, then the next estimateÂ xn+1 is given by

if x0 is sufficiently close to a, xn?a as n?8.

## Limitations of Newton-Raphson Method

- If initial guess is too far away from the required root, the process may converge to some other root.
- Division by zero may occur if fâ€™(xi) is zero or very close to zero.
- A particular value in the iteration sequence may repeat, resulting in an infinite loop.

## Newton-Raphson MATLAB program:

% Newton Raphson Method clear all close all clc % Change here for different functions [email protected](x) cos(x)-3*x+1 %this is the derivative of the above function [email protected](x) -sin(x)-3 % Change lower limit 'a' and upper limit 'b' a=0; b=1; x=a; for i=1:1:100 x1=x-(f(x)/df(x)); x=x1; end sol=x; fprintf('Approximate Root is %.15f',sol) a=0;b=1; x=a; er(5)=0; for i=1:1:5 x1=x-(f(x)/df(x)); x=x1; er(i)=x1-sol; end plot(er) xlabel('Number of iterations') ylabel('Error') title('Error Vs. Number of iterations')

ANSWER :

f =

@(x)cos(x)-3*x+1

df =

@(x)-sin(x)-3

Approximate Root is 0.6071016481031231

### You may also like

- Representation of basic discrete time signal usingÂ MATLAB
- Jacobiâ€™s iterationÂ method
- Lagrange interpolation with MATLABÂ Program
- Simpsonâ€™s 3/8th Rule MATLAB ProgramÂ example
- Simpsonâ€™s 1/3rd rule MATLAB ProgramÂ examples
- MATLAB Programming for Trapezoidal rule withÂ example
- Gauss-Seidel â€“ MATLAB Program andÂ Algorithm

If you like this article, please share it with your friends and like or facebook page for future updates. Subscribe to our newsletter to get notifications about our updates via email. If you have any queries, feel free to ask in the comments section below. Have a nice day!