MATLAB: FEVAL error in implementing Newton’s method.

Question

This is M-File 1

function sol=newtonian(fn,dfn,x0,tol)
tol=0.000001;
old=x0+1; 
while abs (x0 - old) > tol; old=x0; 
  x0=old - feval(fn, old)/feval(dfn, old);
end; 
sol=x0;
end

M-File 2

function y=fn(x0,y)
    x0=2;
    y=(x0).^2-exp(x0)+2;
end

M-File 3

function dy=dfn(x0)
  x0=-2;
  dy=2*(x0)-exp(x0);
end

But I keep getting this ERROR:

??? Error using ==> feval
Argument must contain a string or function_handle.
Error in ==> newtonian at 5
x0=old - feval(fn, old)/feval(dfn, old);

What does this error mean?

Answer 1

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