ode45 second order

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pattara tangjareansuk
pattara tangjareansuk on 18 Apr 2021
please, I want to plot second order and use function ode45. So just now I can't write function.
y" = 3.6sin(t) - 60y - 5y'
and this is my question 👆👆
function dy=model(t,y)
dy = [y(2); 3.6*sin(t) - 60*y(0) - 5*y(1)]
end
and this 👆👆 is my error function

Answers (1)

Alan Stevens
Alan Stevens on 18 Apr 2021
Matlab indices start at 1, so you want
dy = [y(2); 3.6*sin(t) - 60*y(1) - 5*y(2)];
  3 Comments
Alan Stevens
Alan Stevens on 18 Apr 2021
"how can i add sin input to this order"
I'm not sure what you mean. Your second order ode already has 3.6*sin(t) as a forcing function. Do you mean you want to add another term to the forcing function e.g.
y'' + 5*y' + 60*y = 3.6*sin(t) + 2*sin(2*t)
If so, then just make
dy = [y(2); 3.6*sin(t) + 2*sin(2*t) - 60*y(1) - 5*y(2)];
pattara tangjareansuk
pattara tangjareansuk on 18 Apr 2021
i want to create system identification . my professor he said "you should create analytical solution and compare between lsim

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