Finding the zero of a function using Newton Raphson's method in MatLab

I want to find using Newton's method the zero of the function, f(x) to 4d.p. the first positive root, x(first) by writing my code in matlab.

My function is: f(x) = x^4 -6.4x^3 + 6.45x^2 + 20.538x - 31.752 = 0

This is the code that I have so far:

function [root] = newton_simple(func,dfunc,x,tol)

if nargin < 5; tol = 1.0e6*eps; end for i = 1:30 dx = -feval(func, x)/feval(dfunc,x); x = x + dx; if abs(dx) < tol root = x; return end end root = NaN

func = @(x) (x^4 - 64*x^3 + 6.45*x^2 + 20.538*x - 31.752); dfunc = @(x) (4*x^3 - 19.2x^3 + 12.9*x + 20.538); xStart = 2; [root] = newton_simple(func,dfunc,xStart)

[root] = newton_simple(@fex4_7,@dfex4_7,2.0) root = 2.1000

[Jan]

What is your question?

Please read http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup

[John D'Errico]

So what is wrong with that code? If nothing, then why are you posting a question?