function x=fixedpoint(f,xmin,xmax,x0,varargin)
%FIXEDPOINT Fixed point iteration.
%  X=FIXEDPOINT(F,XMIN,XMAX,X0) returns the fixed point X of the map
%  F of the interval [XMIN,XMAX] to itself for starting guess value X0, and
%  plots the corresponding cobweb diagram.
%  X=FIXEDPOINT(F,XMIN,XMAX,X0,P1,P2,...) passes the parameters P1,P2,...
%  to F.

%   Francisco J. Beron-Vera
%   $Revision: 1.0 $  $Date: 2006/09/05 11:52:25 $

clf
x=linspace(xmin,xmax,100);
plot(x,f(x,varargin{:}),'b'), hold on, disp('Press any key to continue.'), pause
plot(x,x,':b'), pause
plot([x0 x0],[0 f(x0,varargin{:})],'r'), pause
k=0;
x1=0;
while abs(x1-x0)>eps*abs(x1)
   k=k+1; 
   if k>25
      warning('Tolerance not satisfied.')
      break
   end
   x=f(x0,varargin{:});
   plot([x0 x],[x x],'r'), pause
   plot([x x],[x f(x,varargin{:})],'r'), pause
   x1=x0;
   x0=x;
end
hold of