function xnew=mnhf_fpi(Fun,xold,tol,Nmax)
%MNHF_FPI Fixed point algorithm for computing the solution to x=g(x).
%
% Fun - name of the external function, g(x).
% xold - initial estimate of the root
% tol - tolerance
% Nmax - maximum number of iterations
%
% Usage  mnhf_fpi(@poly1,1,1e-8,1000);

% Check inputs.
if nargin < 4, Nmax = 1000;  end
if nargin < 3, tol = 1e-8;   end
if (length(xold) ~= 1)
 error('Please provide one initial guess')
end

delta = 1;  % Can select any value with |delta| > tol. 
count = 1;  % Initialize counter. 
while abs(delta)>tol
 xnew = feval(Fun,xold); % Compute new root estimate.
 fprintf('Iteration=%2.0f\t, Current root estimate=%12.8f\n',count,xnew)
 delta = xnew-xold; 

 count = count+1; % Increment counter.
 xold = xnew;              

 if count > Nmax
  error('Maximum number of iterations exceeded.\n\n')
 end

end