function [t,u]=cranknic_bad(odefun,tspan,y,Nh,varargin)
%CRANKNIC  Solve differential equations using the
%  Crank-Nicolson method.
%  [T,Y]=CRANKNIC(ODEFUN,TSPAN,Y0,NH) with TSPAN=[T0,TF]
%  integrates the system of differential equations
%  y'=f(t,y) from time T0 to TF with initial condition
%  Y0 using the Crank-Nicolson method on an equispaced
%  grid of NH intervals.Function ODEFUN(T,Y) must return
%  a column vector corresponding to f(t,y). Each row in
%  the solution array Y corresponds to a time returned
%  in the column vector T.
%  [T,Y] = CRANKNIC(ODEFUN,TSPAN,Y0,NH,P1,P2,...) passes
%  the additional parameters P1,P2,... to the function
%  ODEFUN as ODEFUN(T,Y,P1,P2...).
tt=linspace(tspan(1),tspan(2),Nh+1);
u(:,1)=y;
global glob_h glob_t glob_y glob_odefun;
glob_h=(tspan(2)-tspan(1))/Nh;
glob_y=y;
glob_odefun=odefun;

for glob_t=tt(2:end)
% get only X from fsolve
    w = fsolve('cranknicfun',glob_y);
    u = [u w];
    glob_y = w;
end
t=tt;
clear glob_h glob_t glob_y glob_odefun;
end

function z=cranknicfun(w)
  global glob_h glob_t glob_y glob_odefun;
  z=w-glob_y-0.5*glob_h*(feval(glob_odefun,glob_t,w)+feval(glob_odefun,glob_t,glob_y));
end