Solving non-homogeneous differential equation

I have a second order differential equation: M*x''(t) + D*x'(t) + K*x(t) = F(t) which I have rewritten into a system of first order differential equation.

fun = @(t,q) [q(2) ; -K/M*q(1) - D/M*q(2)] + [0 ; F/M]

Now, I have an array of F-values for different t-values going from 0 to 300 seconds with a step size of 0.1s. K, D and M are just constants which are all known. I want to find the corresponding x-values for the same t-values using the ode45 but I keep getting an error. The initial condition is x(0) = 0 and x'(0) = 0. This is how I use it:

[t y] = ode45(fun,(0:0.1:300),[0 0])

Can anyone tell me what I am doing wrong?

[Talari Nageswari]

i did the same thing

can i get the value of x'(t) and x(t) by using the above van der pol function

Answer 1

[Torsten]

Take a look at the example

"ODE with Time-Dependent Terms"

under

https://de.mathworks.com/help/matlab/ref/ode45.html

Best wishes

Torsten.

Answer 2

[Eric Robbins]

If you're getting a concatenation error try [0*y(2);F/M] so that the first row is consistently sized with the other vectors.