I want to use for loop while solving ode but my code is not running

%Function file
function dxdt = duffng_osc(t,x,f)
global alpha beta omega w ;
dxdt= zeros(3,1);
dxdt(1) = x(2);
dxdt(2) = f*cos(x(3))-alpha*x(2)-omega*x(1)-beta*x(1)^3;
dxdt(3) = w;
end
%Script file
clear all;

global alpha beta omega w ;
alpha = 0.5;
beta = 1;
omega = -1;
w = 1;

%-----------------------------

T_start   = 0;
T_final = 3004*pi;
T_rec   = 2*pi/w;
dt      = pi/100;
n_rec   = round(T_rec/dt);

%----------Initial Conditions-------
x0 = [0 1 0];

%------------Time Interval-----------
tspan = [T_start:dt:T_final];

%-----------Parameter range--------

range = [0.33:0.001:0.57];




 for j=1:length(range)
    f = range(j);
   
     [t,X] = ode45(@(t,x) duffng_osc(t,x,f),tspan,x0);

 end
 

[Walter Roberson]

We recommend against using global

http://www.mathworks.com/help/matlab/math/parameterizing-functions.html

Answer 1

[Walter Roberson]

You are overwriting the output. Try

nrange = length(range);
X = cell(nrange,1);
 for j=1:nrange
    f = range(j);
   
     [t,X{j}] = ode45(@(t,x) duffng_osc(t,x,f),tspan,x0);
     if j == 1
         plot(t, X{j}(:,1:2));
         title( sprintf('range = %f', f));
     else
         plot(t, X{j}(:,1:2) - X{1}(:,1:2))
         title( sprintf('range %f minus range %f', f, range(1)) );
     end
     drawnow
 end

[Ms. Sita]

Thank you so much sir.