> vib_equ returns the first and second derivative of Y(:,1) in dy(1) and dy(2) as well as the first and second derivative of Y(:,3) in dy(3) and dy(4). So what's the problem ? > > Best wishes > Torsten. >
Thank you for your answer.
My problem is that I would like to call vib_equ outside the ode45, but if I do so, I have an error implying that there are undefined variables.
For example if I want to plot both acceleration I need the values of dy(2) and dy(4), but I don't know how to call them.