MATLAB: Duffing equation ODE45

Question

I solved the duffing equation using ODE45. Below is the code.

It works fine and plots as expected. However, I noticed that the difference of 't' is not same. How can I have the 't' value equally spaced?

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tspan = [0 100];

x0=[1,0];

[t,y]=ode45(@duff1,tspan,x0)

figure(1)

%first value

% subplot(221)

plot(t,y(:,1)); %plot(t,y);

xlabel('Time');

ylabel('State');

title('k3=0,k=1,x0=1');

function result = duff1(t,y)

c = 0.1;

k3=0;

k=1;

result= [y(2); -c*y(2)-k*y(1)-k3*y(1).^3]

end

Answer 1

Use:

tspan =  linspace(0, 100, 50);

to create a ‘tspan’ vector with 50 elements between 0 and 100.