Creating a driver routine for my function

Hello,

I am new to MATLAB and going through my textbook example, I have this function that calls two other functions(f and df). It works well when I call it but now I am trying to figure out how to create a driver routine to test this function that specifies the input arguments and calls newtfun.

Below is newtun:

function [x, f, conv] = newtfun(fh, dfh, x0)
steps = 0;
x = x0;
re = 1e-8;
myrel = 1;
while myrel > re & (steps<20)
    xold=x;
    x=x-feval(fh,x)/feval(dfh,x);     
    steps=steps+1;
    disp([x feval(fh,x)])
    myrel = abs(x-xold); %Changing myrel not to divide by x
end
if myrel <=re
    conv=1;
else conv=0;
end
f= feval(fh,x);

For my driver function is this the correct start?

function test_newtfun()
x=[1 2 3];
y = newtfun(x);

I guess I am a little confused. Any help would be much appreciated

Answer 1

[Torsten]

For my driver function is this the correct start?

No. The driver function calls newtfun with three input arguments: The function you search the root of, its derivative (both as function handles) and an initial guess for the root.

Example:

x = newtfun(@(x)x^2-2,@(x)2*x,1)